Flora of North America species comparison

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Draba aurea

Draba cuneifolia

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

wedge leaf Draba
Habit Perennials; (not cespitose); caudex simple or branched; not scapose. Annuals; scapose or subscapose.
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.

(simple to many from or near base), unbranched, (0.2–) 0.3–2.7(–3.7) dm, hirsute or pubescent throughout, trichomes 3–4-rayed, 0.05–0.4 mm, (sometimes mixed proximally with simple or spurred ones, 0.5–1.2 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.

not rosulate;

petiole (obscure), not ciliate;

blade oblanceolate to spatulate or broadly obovate, (0.4–)1–3.5(–5) cm × (2–)6–20(–28) mm, margins dentate (in distal 1/2), surfaces pubescent, abaxially with stalked, 2–4-rayed trichomes, 0.1–0.7 mm, adaxially similar or also with fewer, simple trichomes, 0.4–0.7 mm.
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.

0–6 (on proximal 1/3 of stem);

blade similar to basal.
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.

10–50(–70)-flowered (throughout or on distal 1/3 of scape), ebracteate, elongated in fruit;

rachis not flexuous, densely pubescent, trichomes 2–4-rayed.
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.

(late ones cleistogamous, apetalous);

sepals (green or pink), oblong, 1.5–2.5 mm, glabrous or pubescent, (trichomes simple);

petals white, spatulate, (2–)2.5–4.5(–5) × 1–2 mm, (emarginate or obtuse);

anthers ovate to oblong, (0.1–)0.25–0.4 mm.
Fruiting pedicels

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

horizontal to divaricate-ascending, straight, (1–)2–7(–10) mm, pubescent as rachis.
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.

oblong to linear or lanceolate to broadly ovate, plane, flattened, (3–)6–12(–16) × 1.7–2.7(–3) mm;

valves usually puberulent, rarely glabrous, trichomes simple, antrorse, 0.1–0.3 mm, (rarely with 2-rayed ones, or all trichomes short-stalked, 4-rayed, cruciform);

ovules (12–)24–66(–72) per ovary;

style 0.01–0.3(–0.4) mm.
Seeds

oblong, 0.9–1.3 × 0.5–0.7 mm.

broadly ovoid, 0.5–0.7 × 0.4–0.5 mm.
2n

= 74.

= 30, 32.

Draba aurea

Draba cuneifolia
Phenology Flowering Jun–Aug.
Habitat Rock outcrops, talus, damp gullies and meadows, subalpine conifer woodlands, alpine slopes and turf, tundra, road banks, river gravel
Elevation (0-)700-4200 m ((0-)2300-13800 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
AL; AR; AZ; CA; CO; FL; IL; KS; KY; LA; MO; MS; NC; NE; NM; NV; OH; OK; PA; SD; TN; TX; UT; n Mexico
[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.)

Varieties 3 (3 in the flora).

Draba cuneifolia is highly variable in fruit shape and size, style length, ovule number per ovary, type of fruit indumentum, and length of the fruiting raceme in relation to the rest of the scape. Reported chromosome numbers also vary, but it is currently unclear whether this is the result of biologically relevant processes or erroneous counts. R. L. Hartman et al. (1975) divided the species into three varieties, a position followed by subsequent authors (e.g., R. C. Rollins 1993). Typical var. sonorae is rather distinct (see key below) and may deserve recognition as a separate species, as by O. E. Schulz (1927). Critical, population-based, molecular studies are needed to assess this. In the absence of such studies, we tentatively follow Hartman et al., recognizing three varieties that are distinguished primarily by the types of trichomes found on the fruits. Glabrous-fruited forms occasionally encountered in all three varieties can be difficult to identify.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Key
1. Fruit valves: trichomes usually simple, sometimes with 2-rayed ones; stems hirsute with at least some simple trichomes.
var. cuneifolia
1. Fruit valves: trichomes stalked and 4-rayed, sometimes with 2- or 3-rayed ones; stems pubescent with 3- or 4-rayed trichomes
→ 2
2. Fruits (5-)7-12 mm; ovules 20-44 per ovary; racemes to 3/4 of scape.
var. integrifolia
2. Fruits 3-6(-8) mm; ovules 12-24 per ovary; racemes on all or most of scape.
var. sonorae
Source FNA vol. 7, p. 294. FNA vol. 7, p. 303.
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. chamissonis, D. cinerea, D. corrugata, D. corymbosa, D. crassa, D. crassifolia, D. cruciata, 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
Subordinate taxa
D. cuneifolia var. cuneifolia, D. cuneifolia var. integrifolia, D. cuneifolia var. sonorae
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
Name authority Vahl ex Hornemann: Fors. Oecon. Plantel. ed. 2, 599. (1806) Nuttall ex Torrey & A. Gray: Fl. N. Amer. 1: 108. (1838)
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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