Arabis key for Josephine County

I compiled the following key from the Jepson keyJepson key to Arabis (which does not include A. aculeolata) and the Flora of North America descriptions of the four species present in the county. I do not claim any of the verbiage below as my own.

Another possible reference point is the key at the back of the Oregon Wild plant list for Rough and Ready Wayside.

  1. Hairs on basal leaves with >3 rays, sometimes stellate….. A. modesta
    1’. Hairs on basal leaves simple, 2(4)-rayed, or absent

  2. Stem glabrous….. A. mcdonaldiana
    2’. Stem sparsely to densely hirsute, rarely subglabrate

  3. Hairs on basal leaves mostly simple, often mixed with forked ones; fruit ascending to suberect, not torulose ….. A. aculeolata
    3’. Hairs on basal leaves simple, forked, and often mixes with 3-rayed ones; fruit erect or nearly so, slightly torulose….. A. oregana


A significant majority of Arabis in Josephine County belong to A. aculeolata.

It is likely that A. aculeolata and A. modesta hybridize, producing intermediate individuals. It is unclear to me how to distinguish the hybrid from A. oregana.

A. eschscholtziana is recorded in neighboring Jackson and Curry counties but not in Josephine County, and it is not included in this key. It can easily be distinguished in bloom by its white flowers.

Posted on November 17, 2023 02:03 AM by holyegg holyegg


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