Flora of North America species comparison

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Draba nivalis

Draba standleyi

snow Draba, snow whitlow-grass, yellow arctic Draba

Standley's Draba
Habit Perennials; (cespitose, usually forming mats); caudex branched (covered with persistent leaf bases); usually scapose. Perennials; (densely pulvinate); caudex branched (with persistent, thickened petioles, branches compact); not scapose.
Stems

unbranched, 0.2–0.8(–1.2) dm, pubescent throughout, trichomes minutely stalked, 8–15-rayed, stellate, (non-crisped), 0.03–0.15 mm.

unbranched, 0.3–1.3(–1.7) dm, usually glabrous throughout or sparsely pubescent proximally, rarely sparsely pubescent distally, trichomes simple and 2-rayed, 0.1–0.7 mm.
Basal leaves

rosulate;

petiole (obsolete), ciliate throughout;

blade oblanceolate to obovate, 0.2–0.9(–1.5) cm × 1–3(–5) mm, margins entire, (not ciliate), surfaces usually pubescent, rarely glabrescent, with short-stalked, 8–15-rayed, stellate, (non-crisped) trichomes, 0.05–0.15 mm.

(not imbricate); rosulate; petiolate;

petiole ciliate, (trichomes usually simple, rarely 2-rayed, not setiform);

blade narrowly oblanceolate to linear-lanceolate, (strongly differentiated into blade and petiole), (1.2–)1.8–6(–8.5) cm × 1–5(–7) mm, margins entire or sparsely denticulate, (ciliate as petiole; midvein not prominent), surfaces glabrous or pubescent, usually with simple trichomes 0.1–0.8 mm, rarely 2-rayed.
Cauline leaves

0 or 1;

sessile;

blade ovate or oblong, margins entire, surfaces pubescent as basal.

1–8;

sessile;

blade lanceolate to narrowly oblong, margins usually entire, surfaces pubescent as basal.
Racemes

3–9(–11)-flowered, ebracteate, elongated in fruit;

rachis often slightly flexuous, pubescent as stem.

5–17(–23)-flowered, ebracteate, elongated in fruit;

rachis not flexuous, usually glabrous, rarely pubescent, trichomes simple and 2-rayed, (non-crisped).
Flowers

sepals ovate, 1.5–2 mm, pubescent, (trichomes simple and short-stalked, 2–5-rayed);

petals white, spatulate to oblanceolate, 2–3.5 × 0.8–1.4 mm;

anthers ovate, 0.2–0.3 mm.

sepals ovate, 2–2.5 mm, pubescent, (trichomes simple);

petals yellow, oblanceolate, 4–6 × 1.5–2 mm;

anthers oblong, 0.6–0.8 mm.
Fruiting pedicels

usually ascending, rarely divaricate, straight, 1–4.5(–8) mm, pubescent as stem.

divaricate-ascending or ascending, straight, 3–9(–13) mm, usually glabrous, rarely sparsely pubescent, trichomes simple.
Fruits

elliptic to narrowly oblong-elliptic, twisted or not, flattened, 3.5–9 × 1.5–2.2 mm;

valves usually glabrous, rarely with 3–6-rayed trichomes on replum;

ovules 12–24(–28) per ovary;

style 0.1–0.4 mm.

linear-elliptic to elliptic, twisted or plane, flattened, 5–10(–13) × 1.5–2.5 mm;

valves usually glabrous, rarely puberulent, trichomes simple, 0.05–0.1 mm;

ovules 12–24 per ovary;

style 0.7–1.4(–1.8) mm.
Seeds

ovoid, 0.6–1 × 0.5–0.6 mm.

ovoid, 1–1.2 × 0.7–0.8 mm.
2n

= 16.

Draba nivalis

Draba standleyi
Phenology Flowering Jun–Aug. Flowering Jun–Aug.
Habitat Rock outcrops and fellfields, meadows, open tundra, stream banks, gravelly beaches, roadsides Igneous rock outcrops, stabilized talus slopes
Elevation 0-2500 m (0-8200 ft) 1800-3100 m (5900-10200 ft)
Distribution
from FNA
AK; AB; BC; MB; NF; NT; NU; ON; QC; YT; Greenland; Europe (Finland, Norway [including Svalbard], n, w Sweden); e Asia (Russian Far East, n Siberia); Atlantic Islands (Iceland); circumpolar
[BONAP county map]
from FNA
AZ; NM; TX
[BONAP county map]
Discussion

Draba nivalis is most often confused with D. lonchocarpa, and C. L. Hitchcock (1941) reduced the latter to a variety (var. elongata) of D. nivalis. A critical comparison reveals that there are enough differences to warrant their recognition as distinct species. Draba nivalis is distinguished by having non-ciliate leaf bases, basal leaf blades pubescent with trichomes 0.05–0.15 mm, stems and pedicels that are always pubescent, and fruits that are elliptic to narrowly elliptic-oblong, plane, and 3.5–9 mm. By contrast, D. lonchocarpa has ciliate leaf bases, basal leaf blades pubescent with trichomes 0.15–0.5 mm, stems and pedicels that are glabrous or sparsely pubescent, and fruits that are linear to lanceolate or oblong, slightly twisted or plane, and 6–15(–18) mm. Except for Alaska, D. nivalis does not grow in the continental United States, whereas D. lonchocarpa grows in nearly all Mountain and Pacific states.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Of conservation concern.

Draba standleyi is a distinctive species that is sporadically distributed in the mountains of southwestern United States. It is known from the Chiricahua Mountains (Cochise County, southeastern Arizona), the Organ Mountains and Black Range (Dona Ana and Sierra counties, south-central New Mexico), and the Davis Mountains (Jeff Davis County, western Texas). It has not been reported from Mexico, though it is very likely to occur there.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 7, p. 322. FNA vol. 7, p. 340.
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. 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. 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. spectabilis, D. sphaerocarpa, D. sphaeroides, 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. caesia D. gilgiana, D. chrysantha var. gilgiana
Name authority Liljeblad: Utkast Sv. Fl., 236. (1792) J. F. Macbride & Payson: Ann. Missouri Bot. Gard. 5: 150. (1918)
Web links 
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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