Journal archives for February 2022

04 February, 2022

Proteas with fleshy fruits: a glimpse at the time of dinosaurs?

@hualo @ludovica_ @nitsuga74 @eitel @sur_endemico @nodora @alejandro_karelovic @mark_smale @lloyd_esler @dave_holland @chrise @arthur_chapman @pjd1 @troos @vynbos @cco @rowan_hindmarsh_walls @shauns @botaneek @chris_whitehouse @muisvoel @charles_stirton @adriaan_grobler @graham_g @benjamin_walton @seth @carber @tiggrx @sp_bester @sandraf @andrewm @justinhawthorne @felix_riegel @leejones @annsymons

Proteaceae are so ancient that they coexisted with 'dinosaurs' for at least 25 million years (e.g. see https://cdnsciencepub.com/doi/10.1139/b91-116). This is a period of presumable coevolution with archosaurs longer than the combined Miocene, Pliocene and Pleistocene.

It therefore seems fair to assume that various species of proteas were dispersed and sown by 'dinosaurs' during the Cretaceous.

The presumed mutualism is so archaic that we might have been left with no trace of it in the modern world.

And indeed in southern Africa, where Protea cynaroides is the national flower (https://www.gov.za/about-sa/national-symbols/national-flower#:~:text=The%20giant%20or%20king%20protea,cynara%27%20(the%20artichoke).) and the Cape Floristic Region (https://en.wikipedia.org/wiki/Cape_Floristic_Region) is renowned for several genera of subfamily Proteoideae, there is no species of protea with fleshy fruits (see https://en.wikipedia.org/wiki/Brabejum).

However, the circumstances on several other landmasses have been such that perhaps as many as 20 genera of proteas remain reminiscent of the ancient syndrome.

And it may come as a particular surprise to South African naturalists that proteas with fleshy fruits include:

The role of dispersing and sowing proteas with fleshy fruits has been inherited by various mammals, birds and reptiles. However, no protea has adapted to the modern world to the extent of having fleshy fruits attractive mainly to the relatively small passerine birds - such as Turdidae and Pycnonotidae - typically associated with the consumption of ripe fleshy fruits in Africa, Asia and the Americas.

The main continent retaining proteas with fleshy fruits is Australia. Here, about 110 species, in four subfamilies (Persoonioideae, Grevilleoideae, Proteoideae and Bellendenoideae), have fleshy fruits and seed-dispersal by archaic birds and mammals. These plants vary 150-fold in height from shrubs reaching only 20 centimeters (e.g. see https://en.wikipedia.org/wiki/Persoonia_chamaepitys) to trees reaching 30 meters, but the fruits tend to fall to the ground when ripe regardless.

In Australasia, the main agents of dispersal and sowing seem to be the emu (Dromaius novaehollandiae, https://en.wikipedia.org/wiki/Emu) and cassowaries (Casuarius spp., https://en.wikipedia.org/wiki/Cassowary).

However, marsupials (https://www.cambridge.org/core/journals/journal-of-tropical-ecology/article/abs/seed-dispersal-by-kangaroos-and-their-relatives/B29C68C1FAE97F9FFB2BBB31A7C81DFD and https://www.environment.nsw.gov.au/resources/nature/PpaucifloraEia1200.pdf), certain large passerine birds (https://en.wikipedia.org/wiki/Currawong) and large skinks (e.g. https://www.shutterstock.com/nb/image-photo/eastern-shingleback-tiliqua-rugosa-threatening-open-1655139262 and https://adc.library.usyd.edu.au/view?docId=shesyst/xml-main-texts/shesystv3.xml;database=;collection=;brand=default;;query=tiliqua) also participate in the case of Persoonia (https://kids.kiddle.co/Geebungs).

Only one species of protea with fleshy fruits remains in South America (https://www.inaturalist.org/observations/38519071), associated with the understorey of forests/woodlands of Nothofagus. It is surprising that the agents of dispersal and sowing remain unknown, because its ripening to red (https://eol.org/pages/5510758) makes this one of the brightest-hued on Earth of all the fruits of proteas.

New Zealand, too, retains only one species of protea with fleshy fruits (https://en.wikipedia.org/wiki/Toronia). Here the likely agents were extinct moa (https://en.wikipedia.org/wiki/Moa).

On other Pacific islands, "Weston and Crisp (1996) consider the fruits of Virotia, Kermadecia, Turrillia, and Sleumerodendron to be typical bat fruits, with their dull color, sour or mildly sweet odor, lack of protective rind, and possession of large hard parts." (See page 846 in https://bsapubs.onlinelibrary.wiley.com/doi/pdf/10.3732/ajb.0700006.)

Most of the proteas with fleshy fruits are odd w.r.t. either their survival post-dispersal (grevilleoids) or their germination (persoonioids).

A puzzling aspect of the grevilleoid species is that their relatively large seed-kernels tend to be free of toxins, and thus edible to humans.

A puzzling aspect of the persoonioid species - which unlike the relevant grevilleoids are adapted to wildfires and nutrient-poor soils - is their slow and unpredictable germination (e.g. see https://api.research-repository.uwa.edu.au/ws/portalfiles/portal/10036971/THESIS_DOCTOR_OF_PHILOSOPHY_CHIA_Kerryn_Anne_2016.pdf and https://www.anbg.gov.au/gnp/interns-2009/persoonia-pinifolia.html). Nonetheless, certain species of Persoonia regenerate only germinatively (see section 6.4 in https://www.awe.gov.au/environment/biodiversity/threatened/recovery-plans/persoonia-mollis-subspecies-maxima-2000).

The following compendium of illustrations is arranged in alphabetical order by genus and species. In addition Garnieria spathulifolia (https://en.wikipedia.org/wiki/Garnieria#:~:text=From%20Wikipedia%2C%20the%20free%20encyclopedia%20Garnieria%20is%20a,at%20Prony%20Bay%20in%201868%E2%80%931870%20by%20Benjamin%20Balansa.), some species of Heliciopsis (see https://floraoftheworld.org/taxon/flora/17592186252329) and Bleasdalea may qualify.

Acidonia microcarpa: no photos available
https://florabase.dpaw.wa.gov.au/browse/profile/21315
https://www.inaturalist.org/taxa/472875-Acidonia-microcarpa

Athertonia diversifolia
https://www.inaturalist.org/taxa/528901-Athertonia-diversifolia
https://www.inaturalist.org/observations/104746276

Bellendena montana: no photos of fruits available despite the many photos of flowers
https://www.inaturalist.org/taxa/323299-Bellendena-montana

Catalepidia heyana
https://www.inaturalist.org/taxa/1028637-Catalepidia-heyana
https://apps.lucidcentral.org/rainforest/text/entities/catalepidia_heyana.htm
https://www.bing.com/images/search?view=detailV2&ccid=YKmZ3Nt3&id=C14E674227AF6F66E403C5A9D53C2AB6F995FAB5&thid=OIP.YKmZ3Nt3sw4RBLIdimiAuAHaLH&mediaurl=https%3a%2f%2fth.bing.com%2fth%2fid%2fR.60a999dcdb77b30e1104b21d8a6880b8%3frik%3dtfqV%252bbYqPNWpxQ%26riu%3dhttp%253a%252f%252fwww.anbg.gov.au%252fcpbr%252fcd-keys%252fRFK7%252fkey%252fRFK7%252fMedia%252fImages%252fentities%252fCatalepidia_heyana%252fP070029_BG1244.jpg%26ehk%3dUz%252f47eoKnh1se%252bKqE7en8xvF3AsKVU%252fe8cnzGl%252f74Kk%253d%26risl%3d%26pid%3dImgRaw%26r%3d0&exph=900&expw=600&q=catalepidia+fruits&simid=607995600704588530&FORM=IRPRST&ck=7D8CC8FED36CC2C7535BD4B4F3B5C13C&selectedIndex=1&ajaxhist=0&ajaxserp=0

Cenarrhenes nitida
https://www.inaturalist.org/taxa/323298-Cenarrhenes-nitida
https://www.inaturalist.org/observations/106057578
https://www.inaturalist.org/observations/82760740
https://www.inaturalist.org/observations/77864388
https://www.inaturalist.org/observations/61845410

Gevuina avellana
https://www.inaturalist.org/taxa/490916-Gevuina-avellana
https://zoom50.wordpress.com/2012/01/18/avellano-chileno-chilean-hazel-gevuina-avellana-2/
https://www.inaturalist.org/observations/105673434
https://www.inaturalist.org/observations/101433012
https://www.inaturalist.org/observations/86360387
https://www.inaturalist.org/observations/83827066
https://www.inaturalist.org/observations/71179681
https://www.inaturalist.org/observations/70339280
https://www.inaturalist.org/observations/22422268
https://upload.wikimedia.org/wikipedia/commons/3/30/Avellano_%28Gevuina_avellana%29_leaves_%26_seeds_%28Inao_V%C3%A1squez%29_001.jpg
https://www.rarepalmseeds.com/gevuina-avellana
https://www.pinterest.com.au/amp/pin/412712753351801260/
https://www.alamy.com/chilean-hazelnut-or-avellano-gevuina-avellana-proteaceae-native-to-chile-edible-flowers-and-fruit-chiloe-national-park-cucao-chiloe-island-x-region-of-the-lakes-chile-image226042995.html

Helicia: this genus includes species with fleshy fruits and species in which the fruits ripen dry and brown.

Helicia australasica
https://www.inaturalist.org/taxa/186567-Helicia-australasica
https://www.flickr.com/photos/s_glenum/4434561695
https://www.inaturalist.org/observations/93967175
https://www.territorynativeplants.com.au/helicia-australasica-creek-silky-oak
https://www.flickr.com/photos/xylopia/11621919413
https://landforwildlifetopend.com/2016/05/04/wildflowers-walk-and-macropod-talk/helicia-australasica-2-medium/

Helicia cochinchinensis
https://www.inaturalist.org/taxa/774568-Helicia-cochinchinensis
https://www.inaturalist.org/observations/67996194

Helicia glabrifolia
https://www.inaturalist.org/taxa/370461-Helicia-glabriflora
https://www.inaturalist.org/observations/91702093
https://www.inaturalist.org/observations/63742459

Helicia nortoniana
https://www.inaturalist.org/taxa/919882-Helicia-nortoniana
https://www.inaturalist.org/observations/97622002
https://www.inaturalist.org/observations/104550345

Hicksbeachia pinnatifolia
https://www.inaturalist.org/taxa/538045-Hicksbeachia-pinnatifolia
https://twitter.com/texaninoz/status/1215741634190565377
https://www.inaturalist.org/observations/54377000
https://www.facebook.com/808212652542511/photos/last-year-i-identified-red-bopple-nut-hicksbeachia-pinnatifolia-as-a-host-specie/2579320188765073/
https://www.flickr.com/photos/17674930@N07/50049018293
https://alchetron.com/Hicksbeachia

Kermadecia: no photos available

Persoonia: all of the approximately 100 spp. have fleshy fruits, but most do not change from green when ripe, instead falling to the ground in a state in which the fruit-pulp is green, moist and relatively soft.

Persoonia spp. indet.
https://www.inaturalist.org/observations/102047105
https://www.inaturalist.org/observations/72350903
https://www.inaturalist.org/observations/71928145
https://www.inaturalist.org/observations/67545037

Persoonia falcata
https://www.inaturalist.org/taxa/764693-Persoonia-falcata
https://skipas.wordpress.com/native-plants/plant-families-n-p/proteaceae/persoonia-falcata-wild-pear-or-geebung/
https://www.inaturalist.org/observations/67402259

Persoonia gunnii
https://www.inaturalist.org/taxa/323319-Persoonia-gunnii
https://www.inaturalist.org/observations/104860284
https://www.inaturalist.org/observations/76512999
https://www.inaturalist.org/observations/70790819
https://www.inaturalist.org/observations/38821076
https://www.inaturalist.org/observations/21904761
https://www.inaturalist.org/observations/13510689

Persoonia juniperina
https://www.inaturalist.org/taxa/323847-Persoonia-juniperina
https://www.inaturalist.org/observations/99970446
https://www.inaturalist.org/observations/103673975
https://www.inaturalist.org/observations/95526358
https://www.inaturalist.org/observations/86932752

Persoonia lanceolata
https://www.inaturalist.org/taxa/321208-Persoonia-lanceolata
https://www.inaturalist.org/observations/99856576
https://www.inaturalist.org/observations/61902946

Persoonia linearis (seed mass about 1.9 grams)
https://bushcraftoz.com/threads/persoonia-linearis-narrow-leaved-geebung.1194/
https://www.inaturalist.org/taxa/321204-Persoonia-linearis
https://www.inaturalist.org/observations/84806108
https://www.inaturalist.org/observations/100666655
https://www.inaturalist.org/observations/99597875
https://www.inaturalist.org/observations/87831952
https://www.inaturalist.org/observations/79206640

Persoonia mollis
https://www.awe.gov.au/environment/biodiversity/threatened/recovery-plans/persoonia-mollis-subspecies-maxima-2000
https://resources.austplants.com.au/plant/persoonia-mollis/
https://www.inaturalist.org/taxa/926982-Persoonia-mollis
https://www.inaturalist.org/observations/100669928
https://www.inaturalist.org/observations/82304327

Persoonia muelleri
https://www.inaturalist.org/taxa/883707-Persoonia-muelleri

Persoonia pinifolia
https://www.inaturalist.org/taxa/320841-Persoonia-pinifolia
https://www.inaturalist.org/observations/94206824
https://www.inaturalist.org/observations/84654705
https://www.inaturalist.org/observations/1387705
https://www.inaturalist.org/observations/61453426
https://www.inaturalist.org/observations/93010856
https://www.inaturalist.org/observations/99168142
https://www.inaturalist.org/observations/97724337
https://www.inaturalist.org/observations/97232663
https://www.inaturalist.org/observations/95649789
https://www.inaturalist.org/observations/90745398
https://www.inaturalist.org/observations/89973222
https://www.inaturalist.org/observations/82836948
https://www.inaturalist.org/observations/65563601
https://www.inaturalist.org/observations/59774011

Persoonia silvatica: Floyd (1989) states on page 296: "Drupe, purplish lemon-green...15-18 mm diameter. Flesh edible, mucilaginous and fibrous, tasting like passionfruit."
https://www.inaturalist.org/taxa/1032909-Persoonia-silvatica

Persoonia virgata
https://www.fraserisland.net/fraser-island/fraser-island-plant/bush-tucker
https://www.inaturalist.org/taxa/554191-Persoonia-virgata
https://www.inaturalist.org/observations/95805824

Sleumerodendron: no photos available

Toronia toru
https://www.inaturalist.org/taxa/406557-Toronia-toru
https://www.nzplants.auckland.ac.nz/en/about/seed-plants-flowering/proteaceae/toronia-toru.html
https://www.inaturalist.org/observations/2849986

Triunia youngiana
https://www.inaturalist.org/taxa/554194-Triunia-youngiana
https://www.inaturalist.org/observations/82829422
https://www.inaturalist.org/observations/48398475
https://www.inaturalist.org/observations/46458697

Turrillia: no photos available

Virotia: no photos available

Posted on 04 February, 2022 21:04 by milewski milewski | 16 comments | Leave a comment

08 February, 2022

Leaf-spinescence in Orites, an intercontinental genus of proteas

@tonyrebelo @gregtasney @nyoni-pete @fionagumboots @nigelforshaw @nicfit @kenharris @ninakerr01 @chrisclarke25 @nicklambert @arthur_chapman

Leaf-spinescence - which is perceived as 'prickly' (i.e. somewhat painful) on human skin - occurs on all vegetated continents.

However, it is most noticeable in Australia. This is partly because sclerophylly (lignification of the foliage, https://en.wikipedia.org/wiki/Sclerophyll) is extremely well-developed on this continent.

In Australia (see page 408 in https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1469-185X.2007.00017.x and https://onlinelibrary.wiley.com/doi/10.1111/j.1469-185X.2007.00017.x ):

  • an exceptional number of species are leaf-spinescent,
  • extensive vegetation types are dominated by leaf-spinescent plants (particularly Triodia, https://en.wikipedia.org/wiki/Triodia_(plant)), and
  • most of the leaf-spinescent species belong to genera restricted to this continent.

This is exemplified by Proteaceae.

There are so many leaf-spinescent species of Proteaceae in Australia that it would be hard to count them all. By contrast there are none in either Africa or South and central America, despite the indigenous occurrence of 14 genera in the former and at least five genera in the latter.

The proteaceous genus Orites is worth focussing on because:

  • it has a disjunct 'Gondwanan' distribution, shared between Australia (6 species) and South America (2 species), and
  • its Australian species vary extremely in habitat, and the size and shape of their leaves.

It is true that Orites:

However, what seems to emerge is that the leaf-spinescent species of Orites occur only in Australia, varying in the position of the sharp features on the leaves.

The eight species of Orites can be categorised as follows:

  • two species in South America (fiebrigii of Bolivia and myrtoideus of Chile), neither of which seems to be leaf-spinescent,
  • two species in Australia (lancifolius and revolutus) which are not leaf-spinescent despite being somewhat sclerophyllous,
  • two species in Australia (milliganii and acicularis) which are sclerophyllous and leaf-spinescent (in different ways from each other), and
  • two species in Australia (diversifolius and excelsus), both of which vary from shrubs to trees and have complex patterns of variation in leaf-form.

In the case of the two last-named species, there is leaf-spinescence (albeit weak) in at least some of these forms. This applies particularly to 'juvenile' foliage in the case of the rainforest tree Orites excelsus.

Within Orites in Australia, there is:

  • a ‘kwongan-like’ (https://en.wikipedia.org/wiki/Kwongan) pattern in the shrub genera of alpine Australia, with an emphasis on sclerophylly in wildfire-prone vegetation, which in some species extends to leaf-spinescence, and
  • a ‘rainforest-like’ pattern aligned with e.g. Macadamia (https://en.wikipedia.org/wiki/Macadamia), in which the vegetation is free of wildfire but any leaf-spinescence is more associated with 'juvenile' foliage.

Neither O. milliganii nor O. acicularis dominates vegetation. However, they collectively make for a considerable element of leaf-spinescence in the alpine vegetation of Tasmania. This contrasts with the situation in mainland alpine Australia where the local species of Orites, namely O. lancifolius, is not leaf-spinescent and instead closely resembles O. myrtoideus of Chile.

A third species common in heathland in alpine Tasmania, namely O. revolutus, is not leaf-spinescent. However, as a classic example of evolutionary convergence, it has similar foliage to the daisy Olearia ledifolia (https://en.wikipedia.org/wiki/Olearia_ledifolia). Furthermore, another species of Olearia, also growing in similar habitats, does qualify as leaf-spinescent (https://en.wikipedia.org/wiki/Olearia_pinifolia).

Is there any other continent on which proteas and daisies, growing side-by-side, have such similar foliage that they can be confused by naturalists (https://www.utas.edu.au/dicotkey/dicotkey/AST/ast/sOlearia_ledifolia.htm)?

The following illustrate the species in alphabetical order (note that Orites megacarpus has been transferred to a genus of its own, https://en.wikipedia.org/wiki/Nothorites).

Orites acicularis, of heathlands in Tasmania, has needle-like leaves qualifying as leaf-spinescent in a simple design.
https://www.inaturalist.org/observations/106168936
https://www.inaturalist.org/observations/104506765
https://www.inaturalist.org/observations/73833705
https://www.inaturalist.org/observations/71355514

Orites diversifolius of Tasmania occurs across a range of vegetation types, and varies from shrub to tree. Its leaves are variable but in at least certain situations it seems to exhibit (weak) leaf-spinescence. I do not know how much of this variation is between 'juvenile' and 'adult' foliage, as opposed to being habitat-based.
https://www.inaturalist.org/observations/103230664
https://www.inaturalist.org/observations/9070978
https://www.inaturalist.org/observations/75031990
https://www.inaturalist.org/observations/54499230
https://www.inaturalist.org/observations/38632799

Orites excelsus is the ‘forest tree’ in the genus, growing up to 30 meters high. It shows complex heteroblasty, with the seedling leaves, 'juvenile' leaves and 'adult' leaves all different (https://en.wikipedia.org/wiki/Orites_excelsus). In the 'juvenile' foliage the leaf tends to be pinnasect and toothed. I infer, from the common name ‘prickly ash’, that the teeth sometimes qualify as leaf-spinescent (probably always weakly so, much as in genus Macadamia).
https://www.inaturalist.org/observations/106233716
https://www.inaturalist.org/observations/105231258
https://www.inaturalist.org/observations/104891984
https://www.inaturalist.org/observations/104727924
https://www.inaturalist.org/observations/103942533
https://www.inaturalist.org/observations/103865127
https://www.inaturalist.org/observations/102458160
https://www.inaturalist.org/observations/102867889
https://www.inaturalist.org/observations/102458160
https://www.inaturalist.org/observations/100031867

Orites fiebrigii (Bolivia; no close-up photos of the leaves are available)

Orites lancifolius
https://www.inaturalist.org/observations/106232649
https://www.inaturalist.org/observations/20714643
https://www.inaturalist.org/observations/38823790

Orites milliganii is a shrub of the high-altitude heathlands in Tasmania. It is certainly sclerophyllous, and although the spines on the leaves do not look particularly sharp I think this species qualifies as leaf-spinescent.
https://www.inaturalist.org/observations/101256251
https://www.inaturalist.org/observations/96994917

Orites myrtoideus (Chile)
https://www.inaturalist.org/observations/39095065
https://www.inaturalist.org/observations/68686000
https://www.inaturalist.org/observations/19792150

Orites revolutus
https://www.inaturalist.org/observations/106169154
https://www.inaturalist.org/observations/102400608
https://www.inaturalist.org/observations/66813131
https://www.inaturalist.org/observations/36697163

Posted on 08 February, 2022 02:14 by milewski milewski | 3 comments | Leave a comment

10 February, 2022

How do we make sense of leaf-spinescence in Podocarpus?

@npk @nicfit @coenobita

Among conifers, leaf-spinescence occurs in certain species in the genera Picea (https://www.inaturalist.org/observations/104554252), Juniperus (https://www.inaturalist.org/observations/106243083), and Araucaria (https://www.inaturalist.org/observations/70805032).

It also occurs in a few species of Podocarpaceae, a family occurring mainly in the Southern Hemisphere.

There are 19 genera of podocarps (https://en.wikipedia.org/wiki/Podocarpaceae). The only leaf-spinescent species are several species of Podocarpus and Saxegothaea conspicua.

These can be categorised as follows:

  • New Zealand: Podocarpus totara (tree), Podocarpus laetus (tree) and Podocarpus acutifolius (shrub),
  • southeastern Australia: Podocarpus spinulosus (shrub), and
  • South America: Podocarpus nubigenus (tree, surprisingly similar to totara var. totara of New Zealand), Podocarpus parlatorei (tree), Podocarpus glomeratus (tree), Podocarpus lambertii (tree), and Saxegothaea conspicua (tree).

The biogeographical picture that emerges:
Podocarpus is widespread on southern continents and across the equator to China, Japan and central America. However, it is leaf-spinescent only in South America and southeastern Australasia.

If leaf-spinescence is defensive against folivory, we might expect it to occur mainly:

  • in shrubby species,
  • at the sapling stage of tree species, and
  • in regions with relatively intense folivory.

In podocarps, leaf-spinescence is not particularly associated with shrubby species, thus contradicting predictions.

There is scant information on how leaf-spinescence changes as plants grow from seedling through sapling to mature tree. However, at least in Podocarpus totara it does seem to be true that it is particularly associated with the sapling stage.

With respect to intensity of folivory, no clear trend is apparent.

Kevin Burns has hypothesised that, in Podocarpus in New Zealand, leaf-spinescence shows adaptation to extinct moa (https://www.tandfonline.com/doi/full/10.1080/0028825X.2015.1130727 and https://www.tandfonline.com/doi/full/10.1080/0028825X.2014.997254).

In southern Africa, folivory is particularly intense, and the species of podocarps include both shrubs (Podocarpus elongatus and P. henkelii) and trees (particularly Podocarpus latifolius). Contrary to predictions, no species is leaf-spinescent and P. latifolius is virtually ignored by mammalian folivores - including the savannah elephant (Loxodonta africana) - even at the sapling stage (see https://www.inaturalist.org/journal/milewski/61212-plants-eaten-by-the-savannah-elephant-in-the-cape-floristic-region-part-3#).

Southwestern Western Australia is exceptionally rich in leaf-spinescent plants (particularly shrubs), yet Podocarpus is not leaf-spinescent.

The only podocarp occurring here, Podocarpus drouynianus (https://www.inaturalist.org/taxa/135685-Podocarpus-drouynianus), is specialised as an understorey shrub - never growing taller than 3 meters - in combustion-prone forests of eucalypts. It regenerates from the roots, and fruits only after wildfire. One of its common names hints that its foliage is actually fire-promoting owing to its ‘resin’ content, and if so this is remarkable in a genus generally associated with wildfire-free environments.

The lack of leaf-spinescence in P. drouynianus suggests that podocarps do not follow the ecological patterns set by other leaf-spinescent plants in general.

The explanation suggested by Burns for leaf-spinescence in New Zealand does not seem to apply in South America, where there have been no counterparts for moa.

So it seems that we need to rethink, from scratch, why certain podocarps are leaf-spinescent and why these species mirror each other, approximately, in New Zealand and South America.

The following illustrations of the leaf-spinescent species of podocarps are arranged in alphabetical order.

Podocarpus acutifolius (New Zealand)
https://www.inaturalist.org/observations/104436880
https://www.inaturalist.org/observations/67766856
https://www.inaturalist.org/observations/62269937
https://www.inaturalist.org/observations/6279224

Podocarpus glomeratus (South America)
https://www.inaturalist.org/observations/95208588
https://www.inaturalist.org/observations/75498405
https://www.inaturalist.org/observations/37229525
https://www.inaturalist.org/observations/27366627

Podocarpus laetus (New Zealand)
https://www.inaturalist.org/observations/103446927
https://www.inaturalist.org/observations/90619451
https://www.inaturalist.org/observations/63680565
https://www.inaturalist.org/observations/9923864
https://www.inaturalist.org/observations/8925998

Podocarpus lambertii (South America)
https://www.inaturalist.org/taxa/135630-Podocarpus-lambertii
https://www.inaturalist.org/observations/90216166
https://www.inaturalist.org/observations/86739482

Podocarpus nubigenus (South America)
https://www.inaturalist.org/observations/104370398
https://www.inaturalist.org/observations/49661024
https://www.inaturalist.org/observations/65211377
https://www.inaturalist.org/observations/104816804

Podocarpus parlatorei (South America)
https://www.inaturalist.org/observations/71176095
https://www.inaturalist.org/observations/100028119
https://www.inaturalist.org/observations/64997612
https://www.inaturalist.org/observations/52725210

Podocarpus totara (New Zealand)
https://www.inaturalist.org/observations/45255940
https://www.inaturalist.org/observations/45046558
https://www.inaturalist.org/observations/43190361
https://www.inaturalist.org/observations/42209780
https://www.inaturalist.org/observations/17817035
https://www.inaturalist.org/observations/18485022
https://www.inaturalist.org/observations/11849432

Podocarpus spinulosus (southeastern Australia)
https://www.inaturalist.org/observations/57202753
https://www.inaturalist.org/observations/57202753
https://www.inaturalist.org/observations/41965679
https://www.inaturalist.org/observations/84920489

Saxegothaea conspicua (South America)
https://www.inaturalist.org/taxa/135546-Saxegothaea-conspicua
https://www.inaturalist.org/observations/106251910
https://www.inaturalist.org/observations/105171891
https://www.inaturalist.org/observations/89915794
https://www.inaturalist.org/observations/38799536

Also possibly leaf-spinescent:
Podocarpus sprucei https://www.inaturalist.org/taxa/135718-Podocarpus-sprucei.

Posted on 10 February, 2022 09:55 by milewski milewski | 9 comments | Leave a comment

13 February, 2022

Plasticfruits, part 1: How an ordinary daisy becomes extraordinarily fruity

@chris_whitehouse @peterslingsby @lloyd_esler @adriaan_grobler @botaneek @graham_g @vynbos @troos @benjamin_walton @nicky @craigpeter @jon_sullivan @yvettevanwijk1941 @magdastlucia @joeysantore @alastairpotts @seanprivett @strandloper @arthur_chapman @fynbosphil @henrydelange @qgroom @carinalochner

I have noticed a principle in the biology of plants (https://journals.co.za/doi/abs/10.10520/EJC112757) that seems missing from textbooks.

Ponder the scientific implications of the observation that 'flower' (https://en.wikipedia.org/wiki/Flower) is less ambiguous than 'fruit' (https://en.wikipedia.org/wiki/Fruit).

The principle emerging from this is:
Flowers tend to be evolutionarily fixed, but fruits tend to be evolutionarily plastic.

This is why it is better to classify, and easier to identify, plants by their flowers than by their fruits.

It is also why the word 'flower' is less confusing, in botanical descriptions, than the word 'fruit'.

'Fruit' technically includes dry, dehiscent/ballistic pods and capsules, papery to woody follicles, and diverse other structures. These include compound structures incorporating calyces, peduncles, hypanthia, etc., and can contain from one seed to hundreds. However, 'fruit' is usually taken to mean something closer to the category of fruit in human diets.

Another way of saying this is that plants tend to be conservative in their sexual organs, but versatile in their organs of seed-dispersal. Or relatively fixed vs relatively modifiable. Fruits seem more adaptable than flowers within any given evolutionary lineage.

In this series of Posts, I focus on various examples of this principle at the level of genus (https://en.wikipedia.org/wiki/Genus).

So many genera, worldwide, illustrate the principle of 'plasticfruits' that my choices must be arbitrary. However, I would like to show diverse ways in which fruits have converged, evolutionarily in producing enough 'fleshiness' to provide edible rewards for seed-dispersing animals.

I start with simple - but surprising - examples, building to morphologically more complex examples.

My first choice is the daisy genus Osteospermum (https://en.wikipedia.org/wiki/Osteospermum), which occurs mainly in southern Africa.

The fruit in Osteospermum, as in other daisies (Asteraceae), is a cypsela (https://en.wikipedia.org/wiki/Asteraceae#Fruits_and_seeds) containing a single seed. It is often stated that daisies bear achenes but this is, strictly speaking, incorrect. A cypsela is similar to an achene but differs technically in the number of carpels (https://en.wikipedia.org/wiki/Gynoecium#Carpels).

It is the modification of the exocarp, or outer layer, of the cypsela that provides the main variation - which can be surprisingly eye-catching - in the fruits of various species of Osteospermum.

In some species, the cypsela bears three small wings plus an apical air-chamber, facilitating dispersal by wind. These species tend to occur in dry environments. I do not know whether the wings develop from the exocarp or from the calyx, but I suspect the former.

The fruit is this case would be described by most naturalists as a seed. It is actually a seed contained in the dead, dry carpels, but equates to a seed for practical purposes. (When you shuck a sunflower 'seed', discarding the hull to obtain the real seed inside, you are actually handling a whole fruit of Helianthus, https://en.wikipedia.org/wiki/Helianthus.)

In other species such as Osteospermum spinosum (https://www.inaturalist.org/taxa/591016-Osteospermum-spinosum and https://plants.jstor.org/compilation/osteospermum.spinosum), the cylindrical cypsela has no wing but its exocarp is thinly fleshy. This provides a meagre food-body designed to be eaten by ants as a reward for dispersal and sowing by these insects (https://journals.co.za/doi/pdf/10.10520/AJA00382353_2316 and https://www.researchgate.net/publication/222159641_Convergent_evolution_of_seed_dispersal_by_ants_and_phylogeny_and_biogeography_in_flowering_plants_A_global_survey).

The fleshy layer is thin and colourless, and not noticeable to the human eye. The fruit is not displayed but dropped to the ground immediately on ripening. If the fallen cypsela is not immediately collected by ants, the exocarp dries out and wrinkles within days or perhaps hours.

Here is another example: Osteospermum asperulum (https://www.inaturalist.org/taxa/61411-Osteospermum-asperulum). Also see https://www.sciencedirect.com/science/article/pii/S0254629915302970.

The structure described above is, again, a fruit in botanical terms but would not be described as such colloquially.

In yet other species, the cypsella is ribbed and/or pitted, or kidney-shaped, warty and pitted. The adaptive significance is unknown but this shows how variable the diaspores (https://en.wikipedia.org/wiki/Diaspore_%28botany%29) are within this single genus.

Finally, in a few species of Osteospermum the exocarp of the cypsela is fleshy enough to form something clearly recognisable as a fruit (https://www.inaturalist.org/observations/65954570) - and one that is perfectly edible for humans albeit too small and fiddly for most naturalists to bother with.

In these cases, the exocarp is thick and succulent enough to provide a jam-like reward to birds that swallow the whole cypsela, digest the sugary exocarp, and defecate or regurgitate the seed contained in it, which remains intact after digestion.

The cypsela in these cases not only conforms to the search-image for an edible, fleshy fruit, but changes in hue to present a pre-ripe display. The sequence, from green through yellow and red to blackish, flags to birds the imminent availability of the ripe, palatable exocarp.

The important point:
The flowers of all these species are similar, and unremarkable for daisies. Yet the fruits vary categorically in appearance and function, and this is achieved by evolutionary modification of a single part of the fruit: the exocarp.

If taxonomists were to use the fruits for classification, they would split Osteospermum into different genera. But what fits the evidence better is that this is one genus, with 'plasticfruits'.

The following illustrate the flower-heads, fruits and seeds of Osteospermum moniliferum (https://en.wikipedia.org/wiki/Chrysanthemoides_monilifera). This is dispersed mainly by birds but is one of the few species of daisies, worldwide, that presents fruit-flesh fully edible for humans.

In my experience, the fruits are best eaten when black, at which stage the fruit-pulp has changed from coherent/crisp to fluid. The taste is sweet with no sourness or astringency. I collect about 40 at a time in my mouth, burst them with my tongue one by one, swallow the jam, and spit out the seeds as I go along. I am hardly an agent of dispersal because my instinct is not to swallow the seeds, and I tend to linger at individual plants laden with fruit.

The sequence of colours is as follows. The nearly full-size, but still completely unripe fruits are leaf-green with a purple blush. The full-size but unripe fruits are dull yellowish green. The ripe fruits are brown. The fruit actually shrinks from the yellowish stage to the fully ripe stage, without wrinkling. The fruit-pulp seems to lose some bulk in the conversion from the turgid (still hardly sweet) fruit-pulp at the yellowish stage - which I find myself spitting out rather than eating it - to the ripe, jammy stage.

The following shows that the composite flower-heads are similar to those of thousands of species of daisies worldwide:
https://www.inaturalist.org/observations/71204410

The following show that a limited number of the flowers on each flower-head produce fruits, owing to constraints on space:
https://www.inaturalist.org/observations/71545076
https://www.inaturalist.org/observations/90427230
https://www.inaturalist.org/observations/76601465
https://www.inaturalist.org/observations/99457496
https://www.inaturalist.org/observations/62053603

The following show the development of hues in the pre-ripe display:
https://www.inaturalist.org/observations/100251297
https://www.inaturalist.org/observations/100486869
https://www.inaturalist.org/observations/99216334
https://www.inaturalist.org/observations/98605375
https://www.inaturalist.org/observations/98178097
https://www.inaturalist.org/observations/100865643
https://www.inaturalist.org/observations/99996133
https://www.inaturalist.org/observations/76086368
https://www.inaturalist.org/observations/76088858

The following show the fully-ripe fruits:
https://www.inaturalist.org/observations/100865707
https://www.inaturalist.org/observations/82152373
https://www.inaturalist.org/observations/100865570
https://www.inaturalist.org/observations/85178849

The following show the seeds divested of fruit-pulp by digestion or weathering:
https://www.inaturalist.org/observations/92064511
https://www.inaturalist.org/observations/57777300

to be continued in https://www.inaturalist.org/posts/62134-plasticfruits-part-2-polygalaceae#...

Posted on 13 February, 2022 22:12 by milewski milewski | 9 comments | Leave a comment

15 February, 2022

The West African fauna has lacked not only zebras but also grazing rodents

@maxallen @douglasriverside @oebenin @galat-luong_anh @galewski @zarek @tom_crassard @elisebakker @tandala @oviscanadensis_connerties @jeanpaulboerekamps @mschmidt1966 @i_c_riddell @ricky_taylor @ludwig_muller @jason_van_den_berg

Zebras (Equus spp.) are absent from West Africa (https://en.wikipedia.org/wiki/West_Africa), despite the presence of up to five species in southern and eastern Africa over the past ten thousand years.

It is easy to assume that this absence is because zebras were:

  • formerly present but have been exterminated, and/or
  • ecologically replaced by an extinct form of wild ass.

However, there seems to be no palaeontological or archaeological evidence of zebras anywhere in West Africa - even in the Pleistocene.

Human populations have long been denser in West than in southern Africa, and this is known to have drastically reduced the geographical ranges of wild ungulates - in several cases to the point of near-extermination from West Africa. However, even the giant eland (Taurotragus derbianus) and a giraffe (Giraffa camelopardalis peralta) still remain in small numbers.

It is likely that a form of wild ass, now extinct owing to human influence, formerly occurred in the western Sahel (https://en.wikipedia.org/wiki/Sahel). However, this would still leave a large area of savannah (https://www.bing.com/images/search?view=detailV2&ccid=lVSa7hYs&id=D0F82C8A3D7892E46029FCE344F66BE6CE1FC22B&thid=OIP.lVSa7hYsVahfVyhd2M8lggAAAA&mediaurl=https%3a%2f%2fsites.google.com%2fa%2friverdale.k12.or.us%2fafrican-savannah%2f_%2frsrc%2f1382554373374%2fhome%2fSavannah_Map.gif%3fheight%3d305%26width%3d320&exph=300&expw=314&q=Savannah+Africa+Map&simid=607998714559600287&FORM=IRPRST&ck=C7B96CF2F7967AD7361CF04F46C023D8&selectedIndex=3&ajaxhist=0&ajaxserp=0) - as extensive as the whole of South Africa - naturally devoid of wild equids.

The point of this Post is that a similarly puzzling absence also applies to certain members of the grazing guild that are so fecund that their extermination by humans has been out of the question.

Otomyin murids (https://en.wikipedia.org/wiki/Otomyini) are common and diverse in southern Africa and are specialised for fibrous foods similar to the diets of zebras and asses.

Otomys, Myotomys and Parotomys resemble voles (https://en.wikipedia.org/wiki/Arvicolini) and tropical American grazing rats (https://en.wikipedia.org/wiki/Cotton_rat, https://www.inaturalist.org/observations/50411618 and https://www.inaturalist.org/observations/30708418). They are among the most strictly herbivorous of rat-like, non-amphibious rodents.

The jaws of otomyins are noticeably massive (https://www.inaturalist.org/observations/10831846 and https://www.inaturalist.org/observations/91522485 and https://www.inaturalist.org/observations/90268421) and their molars are adapted for grinding fibrous greens (https://www.natureinstock.com/search/preview/laminate-vlei-rat-otomys-laminatus-skull-adult-ventral-view-of-maxilla/0_11286089.html).

Two of the many species of otomyin rodents do marginally reach West Africa: Otomys occidentalis and Otomys burtoni (https://en.wikipedia.org/wiki/Burton%27s_vlei_rat.). However, these are disjunct relative to the distribution of the rest of the genus, the closest species of which occurs in northern Angola, two thousand kilometers away.

In addition, a large-bodied grazing rodent, Thryonomys gregorianus (https://en.wikipedia.org/wiki/Lesser_cane_rat), is widespread in eastern Africa from southern Zimbabwe northwards - but hardly reaches West Africa.

The absence of these specialised grazing rodents from West Africa can hardly be attributed to human influence. Therefore there seems to be something fundamental in the ecology of this region that has limited the niches of non-ruminant grazers.

The only two species of specialised grazing rodents widespread in West Africa, namely Thryonomys swinderianus (https://en.wikipedia.org/wiki/Greater_cane_rat and https://www.inaturalist.org/observations/104085143) and Dasymys rufulus (https://en.wikipedia.org/wiki/West_African_shaggy_rat), are:

  • largely restricted to the vicinity of permanent water, and
  • shared with southern Africa at the level of species (T. swinderianus) or genus (Dasymys).

Arvicanthis niloticus solatus (https://en.wikipedia.org/wiki/African_grass_rat) and Arvicanthis ansorgei (https://en.wikipedia.org/wiki/Sudanian_grass_rat) fill In ecologically for otomyins to some extent in West Africa, having similar body mass (approximately 100 grams) and eating grasses as staples. However these rats are not as specialised as otomyins and do not resemble voles.

What emerges is an anomalous lack of both zebras and grazing rodents in West Africa.

And, come to think of it, is there any evidence for that even larger specialised grazer, the square-lipped rhino (Ceratotherium simum, https://en.wikipedia.org/wiki/White_rhinoceros), occurring in West Africa - even in the Pleistocene?

Can any reader propose a reason why wild grazers across this large range of body sizes (100 grams to two tonnes) have been unsuited to the savannahs of a wide swathe of Africa from Senegal through Burkina Faso to eastern Nigeria?

Posted on 15 February, 2022 02:46 by milewski milewski | 2 comments | Leave a comment

16 February, 2022

The flora of southern Africa is not diverse enough to emulate hollies, part 1

@ludovica_ @eitel @nodora @mark_smale @dave_holland @chrise @arthur_chapman @pjd1 @troos @vynbos @cco @rowan_hindmarsh_walls @shauns @muisvoel @charles_stirton @adriaan_grobler @graham_g @benjamin_walton @seth @carber @tiggrx @sp_bester @sandraf @andrewm @justinhawthorne @felix_riegel @leejones @annsymons @chris_whitehouse @lloyd_esler @botaneek @nicky @craigpeter @jon_sullivan @magdastlucia @joeysantore @alastairpotts @seanprivett @strandloper @fynbosphil @henrydelange @francoisdurandt @gregtasney @martinbennett @russellcumming @marcoschmidtffm

European holly (Ilex aquifolium, https://en.wikipedia.org/wiki/Holly, and see also https://www.inaturalist.org/taxa/516406-Ilex-colchica) and North American holly (Ilex opaca, https://www.inaturalist.org/taxa/60749-Ilex-opaca) are well-known for mainly non-biological reasons.

(Other similar species occur in China, Taiwan, Mongolia, Korea and Japan: https://www.inaturalist.org/taxa/164038-Ilex-cornuta and https://www.inaturalist.org/taxa/708962-Ilex-bioritsensis and https://www.inaturalist.org/taxa/431139-Ilex-pernyi.)

These plants happen to be evergreen and they happen to have cheerfully ruddy fruits, which remain attached during winter (https://ies-ows.jrc.ec.europa.eu/efdac/download/Atlas/pdf/Ilex_aquifolium.pdf).

Hence they have acquired symbolic meaning, around Christmas, when the rest of the vegetation is drab (https://www.researchgate.net/profile/John-Box/publication/266201917_The_festive_ecology_of_holly_ivy_and_mistletoe/links/542999f40cf27e39fa8e63c0/The-festive-ecology-of-holly-ivy-and-mistletoe.pdf).

However, when viewed through the lens of a naturalist, the familiar hollies of the Northern Hemisphere represent a noteworthy combination of adaptive features. This combination has also arisen - owing to evolutionary convergence - under completely different identities in other floras around the world.

The familiar hollies combine the following two adaptations:

Leaf-spinescence is ecologically significant because it tends to occur in plants adapted to nutrient-poor soils, where foliage tends to be so fibrous that it is unpalatable. Such plants tend to be adapted for consumption by combustion rather than by animals.

(For flammability of hollies see https://d1wqtxts1xzle7.cloudfront.net/41212146/00b7d52af709026b27000000.pdf20160115-19908-hc7hac.pdf?1452874087=&response-content-disposition=inline%3B+filename%3DQUANTIFYING_AND_RANKING_THE_FLAMMABILITY.pdf&Expires=1645055085&Signature=FhtCe47Wu31e~IT8e5G5wPQjWGtLX7hn67O3pD7BJQL2CkIPdljRGG2MNgKMQQJGwC7ueQn6ycSbkpGUVdq6Gxnbj8erCgODyNSQRO5ONqDRnu~8ceqBEEW0PmfWoPthZ2RQYQlcYAeOPKq3ZFLIkiwSo4YAMLA3VSb3dSJmNBDO2z6mPsoKevDDD-NLM5a1gAaTfTnLHCWnEukKjTSAwN5r1E1qGecQjYMCaPQxCJZAp8LiHLazCj45fUBTOzYPW5J-ygBr9cv3IB7ffoKHqjEenscYCWaLkOeExpJmo5J-RzVK9-aiu4545bEz3Un~-pKcYGmDLny5CmuMB18f8w__&Key-Pair-Id=APKAJLOHF5GGSLRBV4ZA and https://www.publish.csiro.au/WF/WF03075.)

Bright-hued, succulent fruit-pulp is ecologically significant because it tends to occur where vegetation is protected from intense wildfires, there is accumulation of organic matter in the soil, and potassium is consequently plentiful (https://www.jstor.org/stable/2844617 and https://www.semanticscholar.org/paper/The-Occurrence-of-Seeds-and-Fruits-Taken-by-Ants-in-Milewski/c8b16a7aa6d2b13a67965de9ab7f4fd9c2ec5a81).

There is obviously some incongruity between nutrient-poverty and potassium-richness, and between flammable and wildfire-free situations.

For this reason, the niches for plants combining leaf-spinescence with fleshy fruits tend to be restricted, and these plants are ecologically noteworthy wherever they occur.

to be continued...

Posted on 16 February, 2022 00:14 by milewski milewski | 11 comments | Leave a comment

17 February, 2022

The flora of southern Africa is not diverse enough to emulate hollies, part 2

One of the overlooked aspects of the flora of southern Africa - which is renowned for its phylogenetic diversity (https://en.wikipedia.org/wiki/Cape_Floristic_Region) - is a lack of any counterpart for the familiar hollies. That is to say, for any species combining leaf-spinescence with fleshy fruits.

In various ways, this lapse is a case of 'so near and yet so far'.

For example:

The species closest to qualifying is Drypetes natalensis (http://treesa.org/drypetes-natalensis/ and http://tropical.theferns.info/viewtropical.php?id=Drypetes+natalensis and https://www.inaturalist.org/taxa/438534-Drypetes-natalensis), which belongs to Putranjivaceae. The 'juvenile' leaves are toothed but not quite rigid enough to be called spinescent, and the fruits are fleshy but tend to wrinkle and harden when ripe. Less ambivalent is a congener in the Caribbean, Drypetes ilicifolia (https://www.inaturalist.org/taxa/1116838-Drypetes-ilicifoliahttps://plantasdepuertorico.blogspot.com/2013/10/encinillo-drypetes-ilicifolia.htmlhttps://plantasdepuertorico.blogspot.com/2014/04/putranjivaceae-drypetes-ilicifolia.html).

The failure of southern African floras to produce any species unambivalently combining leaf-spinescence with fleshy fruits can best be understood by comparison with Australia, where climates and soils are most aligned.

Even in Australia, the area with winter-rainfall and dry summers virtually lacks species with the combination in question. This is clearest in Ericaceae. Several endozoochorous (https://en.wikipedia.org/wiki/Seed_dispersal#Animals:_epi-_and_endozoochory) genera occur in Western Australia, but the fruits are small and dull, and more attractive to ants than to seed-dispersing birds.

It is only in the eastern states of Australia - where the soils are slightly richer and rainfall occurs in both summer and winter - that the combination shifts towards recognisable form (e.g. https://www.inaturalist.org/taxa/321077-Astroloma-humifusum and https://www.inaturalist.org/taxa/321085-Astroloma-conostephioides). The most spectacular examples are in gents Leptecophylla (https://www.inaturalist.org/observations?place_id=any&taxon_id=122665).

The ericaceous genus Leucopogon nicely exemplifies this pattern. Under a winter-rainfall climate, several species are leaf-spinescent, and one species has bright-hued fleshy fruits (https://www.inaturalist.org/observations/36547606). However, no species combines these features - the closest being Leucopogon parviflorus (https://www.inaturalist.org/observations/103908092) with its small whitish fruits.

It is eastward - where rain falls year-round and a degree of geological uplift has slightly rejuvenated the soils - that the combination arises (https://ppnn.org.au/plantlist/leucopogon-juniperinus/ and https://www.wikiwand.com/en/Leucopogon_juniperinus and https://www.inaturalist.org/observations/72007253 and https://www.inaturalist.org/observations/41815524 and https://www.inaturalist.org/observations/102837541).

Whereas transitional climates and soils cover an extensive area in five states of Australia, they cover only a small area in South Africa, mainly in Eastern Cape province (https://en.wikipedia.org/wiki/Eastern_Cape). The chances of a suitable niche arising have been correspondingly greater in Australia than in southern Africa.

And so even a flora as diverse and phylogenetically resourceful as the Cape Flora - producing one of the floristic 'kingdoms' of the world - has not found a suitable opportunity for evolutionary convergence with the familiar hollies of the northern hemisphere.

Posted on 17 February, 2022 00:34 by milewski milewski | 2 comments | Leave a comment

18 February, 2022

List of species combining spinescent leaves and bright-hued fleshy fruits in Australia

(Also see https://www.inaturalist.org/journal/milewski/68420-unusual-combination-of-features-in-ericaceae-the-case-of-acrotriche-serrulata#.)

There are probably more species of plants combining leaf-spinescence and fleshy fruits in Australia than on any other landmass (see https://www.inaturalist.org/journal/milewski/62054-the-flora-of-southern-africa-is-not-diverse-enough-to-emulate-hollies-part-1#).

However, it is as yet difficult to list the Australian species definitively.

This is because:

  • the flora is so diverse that several species are incompletely documented (e.g. in Persoonia),
  • both leaf-spinescence and the fleshiness and bright colouration of fruit-pulp are marginally expressed in many clades,
  • leaf-spinescence may be subject to heteroblasty and/or induced by herbivory, and
  • in Ericaceae, there is a bewildering complex of epacridoid genera that overlap in many features.

Note that in the genus of hollies, Ilex arnhemensis (Aquifoliaceae) is the only species indigenous to Australia. Its leaves are not spinescent.

The following provisional list is arranged alphabetically. Parentheses indicate species that qualify only ambivalently, because the leaves are not clearly spinescent and/or because the fruits are relatively small and dull-hued.

Apocynaceae

Alyxia oblongata https://www.inaturalist.org/taxa/1007849-Alyxia-oblongata and https://www.inaturalist.org/observations/37420900 and https://www.inaturalist.org/observations/100964649

Alyxia ilicifolia https://www.inaturalist.org/taxa/1061187-Alyxia-ilicifolia
and https://www.inaturalist.org/observations/41217468

(Alyxia orophila has weakly spinescent leaves https://www.inaturalist.org/taxa/890229-Alyxia-orophila and https://apps.lucidcentral.org/rainforest/text/entities/alyxia_orophila.htm and http://www.northqueenslandplants.com/Australian%20Plant%20Families%20A-F/Apocynaceae/Alyxia/Alyxia%20orophila.html and https://www.flickr.com/photos/plantnerd/4200135422)

Alyxia ruscifolia https://www.inaturalist.org/taxa/369496-Alyxia-ruscifolia and https://en.wikipedia.org/wiki/Alyxia_ruscifolia and https://www.flickr.com/photos/blackdiamondimages/5997507502

Alyxia sharpei https://www.inaturalist.org/taxa/1077852-Alyxia-sharpei and https://apps.des.qld.gov.au/species-search/details/?id=8353 and https://www.pbase.com/image/53497554

Ericaceae

(Acrotriche aggregata https://www.inaturalist.org/taxa/370609-Acrotriche-aggregata and https://www.inaturalist.org/observations/74005957)

Acrotriche patula https://www.inaturalist.org/taxa/739813-Acrotriche-patula and https://www.inaturalist.org/observations/102293459

(Androstoma verticillatum leaves probably not spinescent but described by Kirkpatrick (1997) as having a 'strong, sharp point' https://www.utas.edu.au/dicotkey/dicotkey/EPACRIDS/gAndrostoma.htm)

(Astroloma humifusum https://www.inaturalist.org/taxa/321077-Astroloma-humifusum)

(Astroloma conostephioides https://www.inaturalist.org/taxa/321085-Astroloma-conostephioides)

Leptecophylla abietina https://www.inaturalist.org/taxa/597402-Leptecophylla-abietina and https://www.utas.edu.au/dicotkey/dicotkey/EPACRIDS/sLeptecophylla_abietina.htmand https://www.inaturalist.org/observations/8906759

Leptecophylla divaricata https://www.inaturalist.org/taxa/803264-Leptecophylla-divaricata and https://www.inaturalist.org/observations/74324068 and https://www.inaturalist.org/observations/75643310

Leptecophylla juniperina https://en.wikipedia.org/wiki/Leptecophylla_juniperina and https://www.inaturalist.org/taxa/143931-Leptecophylla-juniperina and https://www.inaturalist.org/observations/105090920 and https://www.inaturalist.org/observations/101268547

Leptecophylla oxycedrus https://www.inaturalist.org/taxa/1039201-Leptecophylla-oxycedrus and https://www.inaturalist.org/observations/99957374 and https://www.inaturalist.org/observations/87090406 and https://www.inaturalist.org/observations/71334125 and https://www.inaturalist.org/observations/34194242

Leptecophylla parvifolia https://www.utas.edu.au/dicotkey/dicotkey/EPACRIDS/sLeptecophylla_parvifolia.htm and https://about-tasmania.com.au/project/leptecophylla-parvifolia/ and https://www.inaturalist.org/observations/78974045 and https://www.inaturalist.org/observations/104448476 and https://www.inaturalist.org/observations/57805843 and https://www.inaturalist.org/observations/75645264 and https://www.inaturalist.org/observations/2749894

Leptecophylla pendulosa https://www.inaturalist.org/taxa/803302-Leptecophylla-pendulosa and https://www.utas.edu.au/dicotkey/dicotkey/EPACRIDS/sLeptecophylla_pendulosa.htm

Leptecophylla pogonocalyx https://www.inaturalist.org/taxa/803298-Leptecophylla-pogonocalyx and https://www.inaturalist.org/observations/101492452 and https://www.inaturalist.org/observations/17157480 and https://www.inaturalist.org/observations/26739080 and https://www.inaturalist.org/observations/36370129

Leucopogon fraseri https://www.inaturalist.org/taxa/349799-Leucopogon-fraseri

Leucopogon juniperinus https://www.inaturalist.org/taxa/321163-Leucopogon-juniperinus and https://ppnn.org.au/plantlist/leucopogon-juniperinus/ and https://www.wikiwand.com/en/Leucopogon_juniperinus

(Leucopogon parviflorus fruits too small and dull-hued https://www.inaturalist.org/taxa/323832-Leucopogon-parviflorus and https://www.inaturalist.org/observations/103908092)

Leucopogon trichostylus https://www.inaturalist.org/taxa/1033975-Leucopogon-trichostylus and https://www.inaturalist.org/observations/72007253 and https://www.inaturalist.org/observations/41815524 and https://www.inaturalist.org/observations/102837541

(Lissanthe sapida leaves probably do not qualify as spinescent https://www.inaturalist.org/taxa/560968-Lissanthe-sapida and https://www.inaturalist.org/observations/104249805 and https://www.inaturalist.org/observations/103284242 and https://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Lissanthe~sapida and https://www.inaturalist.org/observations/68205834)

Lissanthe strigosa https://wtlandcare.org/details/lissanthe-strigosa/ and https://www.inaturalist.org/observations/21189851

(Monotoca billawinica spinescence of leaves needs confirmation https://www.inaturalist.org/taxa/323215-Monotoca-billawinica)

Monotoca elliptica https://www.inaturalist.org/taxa/323213-Monotoca-elliptica https://www.inaturalist.org/observations/35318001 and https://www.inaturalist.org/observations/68320346

Monotoca glauca leaves spinescent but fruit may remain greenish when ripe https://www.inaturalist.org/taxa/323219-Monotoca-glauca

Monotoca oreophila leaves possibly spinescent https://en.wikipedia.org/wiki/Monotoca_oreophila and https://vicflora.rbg.vic.gov.au/flora/taxon/89fcbaef-6735-4187-9f6b-ca1001bf5fcd

Monotoca scoparia https://www.inaturalist.org/taxa/323189-Monotoca-scoparia and https://www.inaturalist.org/observations/97844879

Styphelia sieberi https://alphitonia.com/EditSpeciesE.cshtml?id=2207

(Styphelia triflora https://www.inaturalist.org/observations/92068025 and https://www.inaturalist.org/observations/35470483)

(Styphelia tubiflora http://anpsa.org.au/s-tub.html and https://en.wikipedia.org/wiki/Styphelia_tubiflora and https://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Styphelia~tubiflora and https://hillsfocus.com.au/?p=1747 and https://www.inaturalist.org/observations/93006140)

Podocarpaceae

Podocarpus spinulosus https://www.inaturalist.org/taxa/135717-Podocarpus-spinulosus

Proteaceae

Persoonia juniperina https://www.inaturalist.org/taxa/323847-Persoonia-juniperina

Posted on 18 February, 2022 00:10 by milewski milewski | 3 comments | Leave a comment

19 February, 2022

Plasticfruits, part 2: Polygalaceae

...continued from https://www.inaturalist.org/journal/milewski/61996-plasticfruits-part-1-how-an-ordinary-daisy-becomes-extraordinarily-fruity#.

In part 1, I described how evolutionarily plastic the fruits are in a mainly southern African genus (Osteospermum) of daisies (Asteraceae).

The genus Muraltia (Polygalaceae) is geographically and ecologically similar to Osteospermum despite belonging to an unrelated family (https://www.sciencedirect.com/science/article/abs/pii/S105579030600337X).

Like Osteospermum, Muraltia (https://en.wikipedia.org/wiki/Muraltia and http://www.flora.sa.gov.au/cgi-bin/speciesfacts_display.cgi?form=speciesfacts&name=Muraltia_heisteria and https://cdn.environment.sa.gov.au/landscape/docs/hf/muraltia-heisteria-may-2019.pdf and http://pza.sanbi.org/muraltia-heisteria) contains wind-dispersed, ant-dispersed (https://www.jstor.org/stable/4621408 and https://www.jstor.org/stable/2260664) and vertebrate-dispersed species.

Although in both genera the seeds have food-bodies attached to them to attract ants, these take different forms. In Osteospermum the food-body is the mesocarp that envelops the seed, but in Muraltia it is a handle-like edible attachment called an elaiosome (https://studylib.net/doc/8932239/elaiosomes-and-seed-dispersal-by-ants and https://en.wikipedia.org/wiki/Elaiosome).

The bright-hued fleshy fruits of Muraltia spinosa and Muraltia scoparia seem adapted for dispersal and sowing mainly by tortoises such as Chersina angulata (https://en.wikipedia.org/wiki/Angulate_tortoise). Unlike those of Osteospermum moniliferum, they remain crisp when ripe and tend to fall to the ground.

Muraltia spinosa
https://www.ingentaconnect.com/content/aspt/sb/2006/00000031/00000003/art00009
http://pza.sanbi.org/muraltia-spinosa

Muraltia scoparia
http://pza.sanbi.org/muraltia-scoparia
https://www.inaturalist.org/taxa/590391-Muraltia-scoparia
https://www.inaturalist.org/observations/10974111

In the case of both Muraltia and Osteospermum, the species dispersed and sown by vertebrates were for several decades classified as separate genera, based on the form of the fruits (https://www.researchgate.net/publication/233494831_Evidence_for_Inclusion_of_South_African_Endemic_Nylandtia_in_Muraltia_Polygalaceae). This has since been corrected with the taxonomic realisation that fruits are too adaptable to be reliable indicators of phylogenetic affinity.

to be continued...

Posted on 19 February, 2022 02:09 by milewski milewski | 1 comment | Leave a comment

20 February, 2022