Draba nemorosa
Yellow Whitlow-Grass

Whole Plant


The weak, undeveloped root and absence of old stems and caudex indicate the plant is an annual.  Note the glabrous upper stem, the presence of a small number (2-5) of cauline leaves, the absence of bracts in the inflorescence, the yellow flowers, and that the mature pedicel is longer than the silique.

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

plants annual, lacking a branched caudex; NOT [plants biennial or perennial, branched caudex and flower stems from previous years often present]

upper stem glabrous; NOT [upper stem pubescent]

cauline leaves usually 2-5; NOT [flowering stems leafless, or at most with a reduced leaf], NOT [cauline leaves usually numerous, often 10-15]

raceme completely ebracteate; NOT [lowest pedicels subtended by bracts]

flowers yellow; NOT [flowers white]

pedicels 1.5-4 times as long as the silique; NOT [pedicels half as long as the silique]

fruit pubescent; NOT [fruits glabrous]


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

plants pubescent; NOT [plants glabrous]

plants not with very large basal leaves; NOT [basal leaves 40 cm long or longer]

siliques a few times longer than wide; NOT [siliques many times longer than wide (Boechera)]

siliques flattened parallel to the septum, at least twice as wide as thick; NOT [siliques flattened at right angles to the septum], NOT [siliques round, oval, or 4-angled in cross-section], NOT [pods subglobose]

silique not samara-like; NOT [silique oblong, wing-like, resembling a samara]

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]

silique rounded to pointed on top or obscurely indented; NOT [silique definitely indented or concave on the top]

silique opening lengthwise; NOT [silique globular, remaining on seed], NOT [silique elongate, breaking in two at the narrowed middle]

silique with >2 seeds in each of the two locules; NOT [silique with 1 to 2 seeds per locule]; NOT [silique 1-seeded]

seeds in 2 rows in each locule (sometimes rows are imperfect); NOT [seeds in 1 row in each locule]


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