Penstemon similar species, part 7: large, round flowers

Summary: this a grouping of species with similar flower shapes that can be found across the western USA. My goal is to provide a brief account for each species as a quick glance reference. I am splitting these into tall and short plants (approximately more or less than 1 foot).

The archetype of the short group is Penstemon eriantherus:

Penstemon atwoodi: localized endemic in southern Utah,
Penstemon breviculus: found in the 4 corners; superficially resembles ophianthus, but flowers are narrower and generally darker purple
Penstemon eriantherus: northern Rockies and PNW states into Canada; unique in its range
Penstemon jamesii: eastern NM, far west TX, SE CO; some overlap with ophianthus in Central NM - look for long, wide cauline leaves, wide, almost rectangular corollas, and generally taller plants (up to 1.5 ft, still much shorter than palmeri)
Penstemon ophianthus: western NM, AZ, southern UT; exserted, coiled staminode with long, golden hairs

The archetype of the tall group is Penstemon palmeri:

Penstemon eximius: Northern Baja peninsula of Mexico,
Penstemon floridus: limited range in southern Nevada and eastern California; bright pink flowers separate it from palmeri; flowers larger and more inflated than stephensii
Penstemon fruticiformis: limited range in southern Nevada and eastern California; linear entire leaves separate it from floridus and palmeri
Penstemon grandiflorus: prairie plant with wide, smooth leaves; may grow wild alongside naturalized populations of palmeri in places like NE Colorado; glabrous staminode and lacks nectar guides
Penstemon grinnellii: southern California (as far north as Sequoia NP) and northern Baja; overlaps with palmeri in eastern California; grinnellii has narrower leaves and grows as a bush/subshrub versus erect flower stalks of palmeri; see also P spectabilis
Penstemon palmeri: widespread in cultivation and across western states; upper leaves serrated, connate across the stem; basal leaves usually grayer than P pseudospectabilis and bicolor (which it hybridizes with in southern NV); leaves similar to P clutei (restricted range in north-central Arizona with smaller, "bubble gum" pink flowers)
Penstemon reidmoranii: Central Baja peninsula of Mexico (adjacent to Isla Cedros),
Penstemon rubicundus: uncommon plant in Mineral and Douglas counties of western NV; bright pink flowers like floridus with exserted staminode like palmeri
Penstemon spectabilis: southern California (LA to San Diego) and northern Baja; purple-blue flowers; interior is lighter in color, lavender to nearly white, with nectar guides and glabrous staminode; serrated, green leaves; upper leaves connate across the stem; basal leaves can be confused with P clevelandii and grinnellii
Penstemon vizcainensis: Central Baja peninsula of Mexico (near Isla Cedros),

Species found in North and Central Mexico with large, abruptly inflated flowers will be covered in this post:

Posted by egordon88 egordon88, 01 September, 2021 16:44


Posted by jdmore over 1 year ago (Flag)

Thanks, I'll add the rubicundus. The others have less inflated flowers and I want to keep this list fairly short.

Posted by egordon88 over 1 year ago (Flag)

Sounds good. Penstemon bicolor is known to hybridize in nature with P. palmeri, so I thought that one could be a potential source of confusion if not mentioned.

Posted by jdmore over 1 year ago (Flag)

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