Boechera collinsii
(Reflexed Rock Cress)
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Flora of North America recognizes two species - Boechera collinsii and Boechera retrofracta - that are very similar. They differ in the pubescence of the proximal stem. B. collinsii has both simple and 2-rayed trichomes, while B. retrofracta has only 2-8-rayed trichomes. The following specimen was determined to be B. collinsii because the proximal stem was examined and photographed.
 Lower Plant |
 Upper Plant |
 Proximal Stem |
|
 Basal Leaf Top |
 Basal Leaf Top |
 Lower Cauline Leaf Top |
 Lower Cauline Leaf Bottom |
 Upper Cauline Leaf Top |
 Upper Cauline Leaf Bottom |
 Basal Leaf Top Close-Up |
 Basal Leaf Bottom Close-Up |
 Flower Side |
 Flower Side, Sepals Removed |
 Single Petal |
 Stamens and Pistil |
 Pistil |
|
 Infructescence |
 Fruit |
B. collinsii / B.
retrofracta
(Reflexed Rock Cress)
Budd's Flora and Flora of Alberta do not distinguish between B. collinsii and B. retrofracta. Therefore the proximal stem was not examined or photographed in these older specimens. As a result I cannot distinguish between the two species in these cases. Budd's Flora uses the name Arabis retrofracta for all of B. collinsii and B. retrofracta, while Flora of Alberta uses the name Arabis holboellii for this group. The notes in the web pages linked to below use the name Arabis holboellii.
