Flora of North America species comparison

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Draba aurea

Draba chamissonis

golden Draba, golden Draba whitlow-grass, golden whitlow-grass, twisted-pod Draba

Cape Thompson Draba
Habit Perennials; (not cespitose); caudex simple or branched; not scapose. Perennials; (cespitose, sometimes forming mats); caudex branched (covered with persistent leaf bases); not scapose.
Stems

sometimes branched distally, (0.5–) 1–3.5(–5.2) dm, pubescent throughout, trichomes simple (non-crisped), 0.4–1.3 mm, and 3–6-rayed ones, 0.1–0.5 mm.

unbranched, 0.4–1.2 dm, pubescent throughout, trichomes minutely stalked, stellate, 8–12-rayed, (non-crisped), 0.03–0.3 mm, sometimes with simple and 2-rayed ones, to 0.3 mm.
Basal leaves

rosulate; petiolate;

petiole (distinct or obscure) ciliate, (trichomes simple, to 0.8 mm);

blade oblanceolate to obovate, (0.4–)1–3.7(–5) cm × (1–)2–7(–10) mm, margins entire or denticulate, surfaces pubescent, trichomes stalked, (2–)4–7 (or 8)-rayed, 0.2–0.5(–0.6) mm.

rosulate;

petiole (obsolete), margin usually not ciliate, (trichomes, when present, simple and 2-rayed, 0.2–0.35 mm);

blade oblanceolate to obovate, 0.4–1 cm × 1–3 mm, margins denticulate or entire, surfaces pubescent with short-stalked, stellate, (non-crisped), 8–12-rayed trichomes, 0.05–0.2 mm, (midvein obscure abaxially).
Cauline leaves

5–20(–26);

sessile;

blade oblong to lanceolate or ovate, margins entire or dentate, surfaces pubescent as basal, sometimes adaxially with simple trichomes.

(1 or) 2–7;

sessile;

blade broadly ovate, margins usually denticulate, rarely entire.
Racemes

(10–)18–52(–72)-flowered, usually bracteate on proximalmost 1–12(–17) flowers, rarely ebracteate, elongated in fruit;

rachis not flexuous, pubescent as stem.

4–10-flowered, proximalmost 1–5 flowers bracteate, elongated;

rachis not flexuous, pubescent as stem.
Flowers

sepals (green or yellowish), oblong, 2.2–3 mm, pubescent, (trichomes simple and branched);

petals yellow, oblanceolate, 3.5–5 × 1.5–2.5 mm;

anthers ovate, 0.4–0.5 mm.

sepals ovate, 1.5–2.2 mm, pubescent, (trichomes simple and short-stalked, 2–5-rayed);

petals white, obovate, 2–3.5 × 1.5–2 mm;

anthers ovate, 0.2–0.3 mm.
Fruiting pedicels

divaricate-ascending to ascending or suberect, straight, 3–13(–20) mm, pubescent as stem.

ascending, straight, (4–)6–13(–20) mm, pubescent as stem.
Fruits

(often subappressed to rachis), lanceolate to linear-lanceolate or narrowly oblong, slightly twisted or plane, flattened, (6–)9–14(–17) × 2–3.5 mm;

valves pubescent, trichomes simple and short-stalked, 2–4-rayed, 0.05–0.3 mm;

ovules 28–38(–44) per ovary;

style 0.5–1.2(–1.5) mm.

linear to narrowly lanceolate, slightly twisted or plane, flattened, 5–11 × 1.1–1.6(–2) mm;

valves glabrous;

ovules 16–20 per ovary;

style 0.1–0.3 mm.
Seeds

oblong, 0.9–1.3 × 0.5–0.7 mm.

ovoid, 0.6–0.9 × 0.3–0.5 mm.
2n

= 74.

= 16.

Draba aurea

Draba chamissonis
Phenology Flowering Jun–Aug. Flowering Jun–Jul.
Habitat Rock outcrops, talus, damp gullies and meadows, subalpine conifer woodlands, alpine slopes and turf, tundra, road banks, river gravel Rock cliffs, bluffs, wind-swept tundra
Elevation (0-)700-4200 m ((0-)2300-13800 ft) 0-500 m (0-1600 ft)
Distribution
from FNA
AK; AZ; CO; ID; MT; NM; NV; SD; UT; WA; WY; AB; BC; MB; NF; NT; NU; ON; QC; SK; YT; Greenland
[WildflowerSearch map]
[BONAP county map]
from FNA
AK; e Asia (Russian Far East, n Siberia)
[BONAP county map]
Discussion

Draba aurea is extremely variable in plant size, number of cauline leaves, number of bracteate flowers, style length, and fruit size, shape, orientation, twisting, and indumentum. Much of the variation in the number of bracts, style length, fruit twisting, and growth habit occurs in Greenland, where the type specimen was collected and where the species is found near sea level.

The highly deviant chromosome counts (e.g., 2n = 40 + 1, 64, 82) listed by R. C. Rollins (1993) and S. I. Warwick and I. A. Al-Shehbaz (2006) are mostly unvouchered and have to be disregarded; counts of 2n = ca. 80 have been re-assigned to Draba glabella. Published (G. A. Mulligan 2002) and unpublished counts made by Mulligan and M. D. Windham from Alaska, British Columbia, Colorado, Quebec, Utah, and Yukon indicate that the most common chromosome number of D. aurea is 2n = 74 (or 72). This suggests that the species is an allopolyploid (hexaploid or higher), incorporating genomes from both euploid and aneuploid lineages (M. A. Beilstein and Windham 2003). Detailed cytological and molecular studies are much needed to fully understand this widely distributed and highly variable species.

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

C. L. Hitchcock (1941) treated Draba chamissonis as a variety of D. nivalis and listed it from British Columbia; R. C. Rollins (1993) did not mention the taxon at any rank. The limited North American material of D. chamissonis that we examined is all from Alaska. The species strongly resembles D. nivalis, from which it is distinguished by having (1 or) 2–7 broadly ovate cauline leaves, proximalmost fruiting pedicels (4–)6–13(–20) mm, petals 1.5–2 mm wide, and fruits 1.1–1.6(–2) mm wide. By contrast, D. nivalis has one ovate or oblong cauline leaf, or none, proximalmost fruiting pedicels 1–4.5(–8) mm, petals 0.8–1.4 mm wide, and fruits 1.5–2.2 mm wide.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 7, p. 294. FNA vol. 7, p. 300.
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. 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. 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. 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. aurea var. aureiformis, D. aurea var. leiocarpa, D. aurea var. luteola, D. aureiformis, D. aureiformis var. leiocarpa, D. bakeri, D. decumbens, D. henneana var. maccallae, D. luteola, D. luteola var. minganensis, D. maccallae, D. minganensis, D. surculifera, D. uber D. frigida var. kamtschatica, D. kamtschatica, D. lonchocarpa subsp. kamtschatica, D. nivalis var. kamtschatica
Name authority Vahl ex Hornemann: Fors. Oecon. Plantel. ed. 2, 599. (1806) G. Don: Gen. Hist. 1: 184. (1831)
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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