Flora of North America species comparison

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Draba densifolia

Draba brachystylis

dense-leaf Draba, dense-leaf whitlow-grass, Nuttall's Draba, Nuttall's whitlow-grass

shortstyle Draba
Habit Perennials; (cespitose, pulvinate); caudex branched (dense with persistent leaf remains, branches sometimes terminating in sterile rosettes); scapose. Annuals or perennials; (short-lived); caudex often simple (poorly developed); not scapose.
Stems

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).

unbranched or branched, 0.6–3(–3.7) dm, pubescent throughout, trichomes simple, 0.4–0.9 mm, and 2–4-rayed, 0.05–0.4 mm.
Basal leaves

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.

rosulate;

subsessile;

petiole base ciliate, (trichomes simple, 0.3–0.9 mm);

blade oblanceolate, 1–3.5 cm × 4–7(–12) mm, margins entire or denticulate, surfaces pubescent, abaxially with stalked, (2–)4-rayed trichomes, 0.1–0.5 mm, adaxially with simple trichomes, 0.2–0.6 mm, with smaller, 2–4-rayed ones.
Cauline leaves

0.

(1 or) 2–6(–8);

sessile;

blade lanceolate or oblanceolate to ovate, margins entire or denticulate, surfaces pubescent as basal.
Racemes

2–10(–22)-flowered, ebracteate, not or slightly elongated in fruit;

rachis not or slightly flexuous, glabrous or pubescent as stem.

(5–)10–35(–47)-flowered, ebracteate, elongated in fruit;

rachis not flexuous, pubescent as stem.
Flowers

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.

sepals ovate, 2–2.7 mm, pubescent, (trichomes simple and short-stalked, 2-rayed);

petals pale yellow (fading white), oblanceolate, 2.5–3.7 × 0.9–1.2 mm;

anthers ovate, 0.2–0.3 mm.
Fruiting pedicels

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).

divaricate-ascending, straight or only slightly curved upward, (1.5–)3–8(–10) mm, pubescent throughout, trichomes simple and stalked, 2–4-rayed.
Fruits

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.

narrowly elliptic to lanceolate, plane, flattened, (7–)10–16(–19) × 2–3.5 mm;

valves pubescent, trichomes simple, spurred, and short-stalked, 2-rayed, 0.05–0.2(–0.3) mm;

ovules 20–36(–42) per ovary;

style 0.2–0.6(–0.8) mm.
Seeds

oblong to ovoid, 1.2–2(–2.6) × 0.9–1.2(–1.4) mm.

oblong, 0.9–1.3 × 0.6–0.7 mm.
2n

= 36.

= 44.

Draba densifolia

Draba brachystylis
Phenology Flowering Jun–Aug. Flowering Jun–Jul.
Habitat Rock outcrops and talus, rocky knolls, alpine ridges Fir and aspen communities, moist areas on rocky slopes
Elevation 800-3700 m (2600-12100 ft) 1700-3000 m (5600-9800 ft)
Distribution
from FNA
AK; CA; ID; NV; OR; UT; WA; WY; AB; BC
[WildflowerSearch map]
[BONAP county map]
from FNA
UT
[BONAP county map]
Discussion

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.)

Of conservation concern.

Based on morphological and chromosomal data (L. Allphin and M. D. Windham, unpubl.), Draba brachystylis is hypothesized to be an allopolyploid derived through hybridization between D. albertina and D. santaquinensis. It is known to us only from Cache, Duchesne, Juab, Salt Lake, and Utah counties. C. L. Hitchcock (1941) indicated that the species grows in the Charleston Mountains of Clark County, Nevada, but we have not seen unequivocal material of it from that area.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 7, p. 306. FNA vol. 7, p. 297.
Parent taxa Brassicaceae > tribe Arabideae > Draba Brassicaceae > tribe Arabideae > Draba
Sibling taxa
D. abajoensis, D. albertina, D. aleutica, D. alpina, D. aprica, D. arabisans, D. arctica, D. arctogena, D. argyrea, D. arida, D. asprella, D. asterophora, D. aurea, D. aureola, D. bifurcata, D. borealis, D. brachycarpa, D. brachystylis, D. breweri, D. burkei, D. californica, D. cana, D. carnosula, D. chamissonis, D. cinerea, D. corrugata, D. corymbosa, D. crassa, D. crassifolia, D. cruciata, D. cuneifolia, D. cusickii, D. cyclomorpha, D. daviesiae, D. exunguiculata, D. fladnizensis, D. glabella, D. globosa, D. graminea, D. grandis, D. grayana, D. heilii, D. helleriana, D. hitchcockii, D. howellii, D. incana, D. incerta, D. incrassata, D. inexpectata, D. jaegeri, D. juvenilis, D. kassii, D. kluanei, D. lactea, D. lemmonii, D. lonchocarpa, D. longisquamosa, D. macounii, D. maguirei, D. malpighiacea, D. micropetala, D. mogollonica, D. monoensis, D. mulliganii, D. murrayi, D. nemorosa, D. nivalis, D. norvegica, D. novolympica, D. oblongata, D. ogilviensis, D. oligosperma, D. oreibata, D. oxycarpa, D. palanderiana, D. pauciflora, D. paucifructa, D. paysonii, D. pectinipila, D. pedicellata, D. pennellii, D. petrophila, D. pilosa, D. platycarpa, D. porsildii, D. praealta, D. pterosperma, D. ramosissima, D. ramulosa, D. rectifructa, D. reptans, D. ruaxes, D. santaquinensis, D. saxosa, D. scotteri, D. serpentina, D. sharsmithii, D. sibirica, D. sierrae, D. simmonsii, D. smithii, D. sobolifera, D. spectabilis, D. sphaerocarpa, D. sphaeroides, D. standleyi, D. stenoloba, D. stenopetala, D. streptobrachia, D. streptocarpa, D. subalpina, D. subcapitata, D. subumbellata, D. trichocarpa, D. ventosa, D. verna, D. viridis, D. weberi, D. yukonensis, D. zionensis
D. abajoensis, D. albertina, D. aleutica, D. alpina, D. aprica, D. arabisans, D. arctica, D. arctogena, D. argyrea, D. arida, D. asprella, D. asterophora, D. aurea, D. aureola, D. bifurcata, D. borealis, D. brachycarpa, D. breweri, D. burkei, D. californica, D. cana, D. carnosula, D. chamissonis, D. cinerea, D. corrugata, D. corymbosa, D. crassa, D. crassifolia, D. cruciata, D. cuneifolia, D. cusickii, D. cyclomorpha, D. daviesiae, D. densifolia, D. exunguiculata, D. fladnizensis, D. glabella, D. globosa, D. graminea, D. grandis, D. grayana, D. heilii, D. helleriana, D. hitchcockii, D. howellii, D. incana, D. incerta, D. incrassata, D. inexpectata, D. jaegeri, D. juvenilis, D. kassii, D. kluanei, D. lactea, D. lemmonii, D. lonchocarpa, D. longisquamosa, D. macounii, D. maguirei, D. malpighiacea, D. micropetala, D. mogollonica, D. monoensis, D. mulliganii, D. murrayi, D. nemorosa, D. nivalis, D. norvegica, D. novolympica, D. oblongata, D. ogilviensis, D. oligosperma, D. oreibata, D. oxycarpa, D. palanderiana, D. pauciflora, D. paucifructa, D. paysonii, D. pectinipila, D. pedicellata, D. pennellii, D. petrophila, D. pilosa, D. platycarpa, D. porsildii, D. praealta, D. pterosperma, D. ramosissima, D. ramulosa, D. rectifructa, D. reptans, D. ruaxes, D. santaquinensis, D. saxosa, D. scotteri, D. serpentina, D. sharsmithii, D. sibirica, D. sierrae, D. simmonsii, D. smithii, D. sobolifera, D. spectabilis, D. sphaerocarpa, D. sphaeroides, D. standleyi, D. stenoloba, D. stenopetala, D. streptobrachia, D. streptocarpa, D. subalpina, D. subcapitata, D. subumbellata, D. trichocarpa, D. ventosa, D. verna, D. viridis, D. weberi, D. yukonensis, D. zionensis
Synonyms D. caeruleomontana, D. caeruleomontana var. piperi, D. glacialis var. pectinata, D. globosa var. sphaerula, D. mulfordiae, D. nelsonii, D. oligosperma var. pectinata, D. pectinata, D. sphaerula
Name authority Nuttall: in J. Torrey and A. Gray, Fl. N. Amer. 1: 104. (1838) Rydberg: Bull. Torrey Bot. Club 29: 240. (1902)
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Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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