Journal archives for September 2019

September 05, 2019

False Foxgloves: how to know the species of Agalinis in Texas

False Foxgloves (Agalinis) produce attractive, purple blossoms in late summer through fall. The distribution of these species are poorly documented, so our observations can help with that. There are several species in Texas that are quite similar yet unique in subtle ways.

Here's a guide that I put together as an attempt to note distinguishing features: https://docs.google.com/presentation/d/1jQ4yVFHhCZ2Yhy7v_Z3ngp-tZIvOKN3UtCBm0mOBbg4/edit?usp=sharing

Generally speaking, here are some features that must be documented (always take pictures of multiple flowers and multiple stems to capture the variation):

  • length of flowering pedicel (relative to length of calyx)
  • length of leaves relative to pedicels
  • orientation of leaves (clasping stem or perpendicular to stem)
  • length of corolla lobes (all the same, or upper shorter than lower)
  • orientation of upper corolla lobes (reflexed or arching over stamens)
  • size of flower (pay attention if small: 8-13 mm long)
  • length of lobes of calyx (relative to tube of calyx)
  • shape of leaves (threadlike, flat-narrow, flat-broad, divided)
  • leafyness (presence of well developed axillary fascicles "extra leaves")
  • I recommend that folks carry with them a white pillow case to use as a backdrop for photographing the plants (if you're serious about getting a good ID--especially for those rare eastern species where leaf length, shape, and density are critical).

BONAP maps of Agalinis: http://bonap.net/Napa/TaxonMaps/Genus/County/Agalinis (not accurate or up to date)

Posted on September 05, 2019 14:36 by pfau_tarleton pfau_tarleton | 19 comments | Leave a comment