Draba

Draba is a large and complex genus, mostly of alpine, boreal and arctic regions, represented by only a few relatively distinctive species in our area. The siliques are strongly flattened and in many species are ± twisted.

1. Petals deeply bilobed; stems leafless, all leaves in a basal rosette.

D. verna

1. Petals entire or slightly notched at apex; plants with at least some cauline leaves near the base of the stem.

2. Plant a delicate slender-stemmed annual (or winter-annual); fruit narrowly elliptic or oblong, tapering no more toward the apex than the base and no broader below the middle than at it; axis of the inflorescence glabrous.

3. Petals pale yellow, less than 2.2 mm long; cauline leaves scattered nearly to the open, elongate raceme.

D. nemorosa

3. Petals white, ca. 3–4 mm long (or absent); cauline leaves near the base (sometimes scarcely distinguishable from the basal rosette), remote from the crowded inflorescence.

D. reptans

2. Plant a ± strong perennial (or sturdy biennial); fruit mostly slightly broader below the middle, tapering more toward the apex than the base; axis of inflorescence usually sparsely to densely pubescent.

4. Stem very leafy (at least 20 cauline leaves between basal rosette and lowest pedicel); axis of inflorescence densely pubescent; fruit not twisted.

D. incana

4. Stem with few cauline leaves but many basal leaves (often with short leafy basal shoots); axis of inflorescence sparsely pubescent or glabrate.

5. Fruit ± densely stellate pubescent.

D. cana

5. Fruit glabrous or sparsely pubescent when young.

6. Style 0.25–0.5 mm long, clearly longer than broad; fruit usually spirally twisted ca. 1/4 to a full turn.

D. arabisans

6. Style ca. 0.2 mm long, about as wide as long; fruit flat, not spirally twisted.

D. glabella

All species found in Draba

Draba arabisansROCK WHITLOW-GRASS 
Draba canaASHY WHITLOW-GRASS 
Draba glabellaSMOOTH WHITLOW-GRASS 
Draba incanaTWISTED WHITLOW-GRASS 
Draba nemorosaWHITLOW-GRASS 
Draba reptansCOMMON WHITLOW-GRASS 
Draba vernaWHITLOW-GRASS 

Citation:

MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. December 12, 2017. http://www.michiganflora.net/genus.aspx?id=Draba.