Journal archives for November 2019

November 23, 2019

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 on November 23, 2019 15:59 by pfau_tarleton pfau_tarleton | 4 comments | Leave a comment