Draba densifolia
Brassicaceae tribe Arabideae
dense-leaf Draba, dense-leaf whitlow-grass, Nuttall's Draba, Nuttall's whitlow-grass
unbranched, (0.05–)0.2–1(–1.7) dm, usually glabrous, rarely pubescent, trichomes usually simple, 0.3–0.8 mm, and 2–4 (or 5)-rayed, 0.1–0.6 mm, (rarely predominantly simple ones).
rosulate;
sessile;
blade linear to oblong or oblanceolate-linear, 0.3–0.9(–1.4) cm × 0.5–1.5(–2) mm, margins entire, (ciliate, trichomes simple, 0.3–1.2 mm), surfaces glabrous or sparsely pubescent, abaxially with short-stalked, 2–4-rayed trichomes, 0.1–0.3 mm (midvein prominent), adaxially rarely with subapical, simple trichomes.
0.
petiolate or sessile;
blade base auriculate or not, margins entire or dentate.
2–10(–22)-flowered, ebracteate, not or slightly elongated in fruit;
rachis not or slightly flexuous, glabrous or pubescent as stem.
usually ebracteate, often elongated in fruit.
sepals ovate, 2–3 mm, usually sparsely pubescent, rarely glabrous, (trichomes simple and short-stalked, 2–4-rayed);
petals pale yellow (sometimes fading white), oblanceolate to obovate, 2–5 × 1–1.7(–2) mm;
anthers ovate or oblong, 0.4–0.6 mm.
actinomorphic;
sepals erect, ascending, or spreading, lateral pair seldom saccate basally;
petals white, yellow, orange, pink, or purple, claw usually present, usually distinct;
filaments unappendaged, not winged;
pollen 3-colpate.
divaricate-ascending to ascending (not decurrent basally), straight, (0.7–)1.5–10(–25) mm, usually glabrous, rarely sparsely pubescent, trichomes predominantly simple (0.2–0.7 mm), sometimes 2–4 (or 5)-rayed, (0.1–0.5 mm).
ovoid or ovate-lanceolate, plane (not curved), flattened, (2.5–)3–6(–8) × 2–3 mm;
valves pubescent or puberulent, trichomes simple and short-stalked, 2–5-rayed, 0.1–0.4 mm;
ovules 4–12 per ovary;
style 0.3–0.6(–1) mm.
silicles or siliques, usually dehiscent, very rarely indehiscent, unsegmented, latiseptate or terete;
ovules 2–70(–88)[–110+] per ovary;
style usually distinct, sometimes obsolete;
stigma usually entire, rarely 2-lobed.
oblong to ovoid, 1.2–2(–2.6) × 0.9–1.2(–1.4) mm.
biseriate or uniseriate [rarely aseriate];
cotyledons accumbent.
stalked or sessile, usually stellate, dendritic, cruciform, or forked, sometimes mixed with simple ones, rarely malpighiaceous.
= 36.
Draba densifolia
Brassicaceae tribe Arabideae
Draba densifolia is one of the most highly variable North American members of the genus, as evidenced by the extensive synonymy. The species is an apomict (G. A. Mulligan 1976) and it occupies tremendous geographic, edaphic, and altitudinal ranges. In forms corresponding to the type of D. sphaerula, the flowering stems are 2-flowered, and the stems, leaves, and fruiting pedicels are to 5, 1.5, and 0.6 mm, respectively. By contrast, forms comparable to the type of D. caeruleomontana var. piperi have stems, leaves, and fruiting pedicels to 17, 1.3, and 2.5 cm, respectively. Between these remarkable extremes fall all of the other populations of the species.
Draba densifolia is sometimes confused with D. paysonii, which it resembles, in being a cespitose, scapose, and densely pulvinate perennial having narrowly linear or oblong to linear-oblanceolate leaf blades with strongly ciliate margins. It is easily distinguished from the latter by having glabrous adaxial leaf blade surfaces, only sparsely pubescent abaxial surfaces, and often glabrous fruiting pedicels and rachises.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Genera 8, species ca. 460 (4 genera, 139 species in the flora).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
- Local floras:
BC, 
CA, 
OR, 
WA - Local Web sites: CalFlora, CalPhotos,
Flora NW, 
PNW Herbaria, Turner Photog. 
WildflowerSearch
iNaturalist (observations)
USDA Plants Database- LBJ Wildflower Center
- SEINet
- Plants of the World Online
- Encyclopedia of Life
- Wikipedia
- Google Image Search
