Flora of North America species comparison

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Draba densifolia

Draba spectabilis

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

showy Draba, showy whitlowgrass
Habit Perennials; (cespitose, pulvinate); caudex branched (dense with persistent leaf remains, branches sometimes terminating in sterile rosettes); scapose. Perennials; caudex simple or branched (sometimes with persistent leaf bases); 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, (0.7–)1.1–3.7(–5.3) dm, pubescent throughout (sparsely so distally), trichomes simple, malpighiaceous, or sessile and 4-rayed, 0.15–0.5 mm, (2 rays parallel to stem axis longer).
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; petiolate;

petiole sometimes ciliate, (trichomes simple);

blade oblanceolate to spatulate or obovate, (1–)1.5–4.4(–6.3) cm × (3–)5–12(–15) mm, margins entire or dentate, surfaces pubescent with sessile, often 4-rayed trichomes, 0.1–0.6 mm (longest rays parallel to midvein, lateral rays sometimes reduced to tiny spurs), sometimes malpighiaceous trichomes present.
Cauline leaves

0.

4–12(–17);

sessile;

blade broadly ovate to lanceolate or oblong, margins entire or dentate, (ciliate or not), surfaces pubescent as basal or adaxially also with simple trichomes.
Racemes

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

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

(10–)16–49(–61)-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–)2.5–4 mm, glabrous or pubescent, (trichomes simple and malpighiaceous);

petals yellow, oblanceolate, 4–6.5 × 1–2.5 mm;

anthers oblong, 0.5–0.7 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).

horizontal to divaricate-ascending, straight or curved upward, (5–)7–20(–26) mm, glabrous or pubescent as rachis abaxially.
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.

lanceolate to oblong or elliptic, plane, flattened, (6–)7–13 × 2–3.5 mm;

valves glabrous or puberulent, trichomes simple and sessile, 2-rayed, 0.03–0.3 mm;

ovules 12–24 per ovary;

style (0.5–)1–2.7 mm.
Seeds

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

ovoid, 1–1.4 × 0.7–0.9 mm.
2n

= 36.

= 40.

Draba densifolia

Draba spectabilis
Phenology Flowering Jun–Aug. Flowering Jun–Aug.
Habitat Rock outcrops and talus, rocky knolls, alpine ridges Talus, rocky hillsides, meadows in open conifer forests, aspen groves, and alpine communities
Elevation 800-3700 m (2600-12100 ft) 2000-3900 m (6600-12800 ft)
Distribution
from FNA
AK; CA; ID; NV; OR; UT; WA; WY; AB; BC
[WildflowerSearch map]
[BONAP county map]
from FNA
CO; NM; WY
[WildflowerSearch map]
[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.)

Morphological and chromosomal data suggest that Draba spectabilis is an allopolyploid resulting from hybridization between D. abajoensis and D. malpighiacea. The characteristics distinguishing these three taxa were discussed in detail by I. A. Al-Shehbaz and M. D. Windham (2007). Chromosome counts attributed to D. spectabilis by Windham (2000) represent diploid D. abajoensis.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 7, p. 306. FNA vol. 7, p. 339.
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. 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. 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. 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 D. oxyloba, D. spectabilis var. bella, D. spectabilis var. oxyloba, D. spectabilis var. purpusii
Name authority Nuttall: in J. Torrey and A. Gray, Fl. N. Amer. 1: 104. (1838) Greene: Pittonia 4: 19. (1899)
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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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