Arabis divaricarpa

 Purple Rock Cress

Upper Stem Leaf Top

West Block, Cypress Hills

Divaricarpa: Answers to key questions in Budd's Flora and Manual of Montana Vascular Plants leading to this species. 

plants 20-80 cm high; NOT [plants 10-20 cm high]

caudex usually simple or few-branched, not woody; NOT [caudex usually branched and woody]

stems arising from terminal bud of the rosette; NOT [outer stems decumbent-based, arising from lateral buds, basal leaves erect]

most stems > 1mm wide; NOT [stems <= 1 mm wide in the middle]

pubescence of lower stems sparse and 2- to 3-branched; NOT [pubescence of lower stems more branched]

NOT [basal leaves often blunt-tipped, felt-like with dense branched hairs]

cauline leaves auriculate; NOT [cauline leaves without auricles]

cauline leaves not rolled; NOT [margins of cauline leaves rolled under]

cauline leaves not whitish-hairy; NOT [cauline leaves whitish with dense hair]

at least some siliques spreading; NOT [all siliques erect or ascending], NOT [all siliques sharply reflexed and pendulous]

siliques 5-10 cm long; NOT [siliques 1-5 cm long]

siliques 1-2 mm wide, often > 1.5 mm wide; NOT [siliques 1.5-3.5 mm wide], NOT [siliques always <= 1.5 mm wide]


Arabis: Answers to key questions in Budd's Flora and Manual of Montana Vascular Plants leading to this genus. 

basal leaves entire to shallowly dentate; NOT [basal leaves deeply lobed or divided into leaflets]

plants with pubescence mostly or entirely of branched hairs; NOT [plants glabrous, or the pubescence of simple hairs]

flowers much smaller; NOT [flowers 20-25 mm across]

silique not samara-like

siliques linear to oblong, > 5 times as long as wide

siliques flattened parallel to the septum; NOT [siliques flattened at right angles to septum]; NOT [siliques round or 4-angled in cross section]

silique beakless, often with a short style at the tip <= 1 mm long; NOT [silique with a large, usually seedless (sometimes 1-seeded), beak-like, upper portion and a seed-bearing lower portion]

central partition entire; NOT [central partition with an opening sometimes almost reduced to the margin]

silique with more than one seed; NOT [silique 1-seeded]


Cruciferae: Answers to key questions in Budd's Flora  leading to this family. 

herbs; NOT [shrubs or trees]

plants terrestrial or semiaquatic; NOT [plants aquatic, leaves submerged or floating]

plants not with colored milky juice

plants with more than one normal leaf

some or all leaves alternate; NOT [leaves opposite, whorled, or basal]

leaves without stipules, or having glands; NOT [leaves with stipules]

flowers with two floral rings

calyx regular; NOT [calyx irregular, some sepals smaller than others]

sepals 4

corolla regular in shape; NOT [corolla irregular in shape]

each petal distinct from the others

petals 4

stamens 6, four long and two short

ovary superior; NOT [ovary inferior]

carpels 1 or 2