How to know the Texas Arabideae (Genera Draba, Abdra, and Tomostima)

Species of the Tribe Arabideae are among the first flowers to bloom (January--March or early April). Being small and inconspicuous, they are often overlooked (especially Draba reptans. Observations of Texas Arabideae are here. These species have been lumped and split, taxonomically; recently, all were in the genus Draba. The following characteristics vary, so documenting multiple characteristics will confirm the ID. Features to capture include:

  • side view of mature fruits (pods)
  • side view of flowering stem (pedicel) from top to bottom (with hairs in focus)
  • view of leaves
Also, young plants may be challenging or impossible to identify.
  • 1. The hairs on leaves and stems lie flat (appressed); mature fruit <5 mm long: Abdra brachycarpa (formerly Draba) [resource]
  • 1. The hairs on leaves and stems are upright (perpendicular to surface); mature fruit 5-15 mm long
    • 2. Pedicels (flowering stem) smooth (glabrous); leaves always entire (not notched): Tomostima reptans (formerly Draba) [resource]
    • 2. Pedicels pubescent; at least some leaves usually with 1+ pair of teeth


      • 3. Leaves crowded near base; fruit elongate, blade-like; hairs along the stem branched: Draba cuneifolia [resource]

      • 3. Leaves extending up stem: fruit oval, football-shaped; many hairs along the stem unbranched: Draba platycarpa [resource]

    *There is also a yellow-flowered species in Jeff Davis county (Trans-Pecos): Draba standleyi
Posted by pfau_tarleton pfau_tarleton, November 23, 2019 15:59

Comments

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Thanks - I’ll be prepared for these this year!

Posted by lisa281 over 1 year ago (Flag)
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Whew. I remember trying to wrestle with Draba a while back and getting super confused... I think it was mostly youngsters that I was trying to ID (before fruits developed).

Anywho, great journal entry again, Russell! :) Thanks for curating these genera!

Posted by sambiology over 1 year ago (Flag)
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Ahhh... I missed this post. It was probably during my forced holiday break. Bookmarking!

Posted by kimberlietx over 1 year ago (Flag)
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Ah, thank you! I'm bookmarking, too!

Posted by annikaml 4 months ago (Flag)

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