Flora of North America species comparison

The green links below add additional plants to the comparison table. Blue links lead to other Web sites.
enable glossary links

Draba aurea

Draba lactea

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

milky Draba, milky whitlow-grass
Habit Perennials; (not cespitose); caudex simple or branched; not scapose. Perennials; (cespitose); caudex branched (with persistent petiole remains, branches sometimes terminating in sterile rosettes); 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, 0.2–1.1(–1.5) dm,glabrous throughout or sparsely pubescent proximally, trichomes short-stalked, substellate, 2–8-rayed, (non-crisped), 0.5–0.3 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; petiolate;

petiole (persistent, strongly thickened), margin usually ciliate, (trichomes usually simple and 2-rayed, 0.3–1 mm);

blade oblanceolate to obovate, (0.3–)0.5–1.1(–1.7) cm × (1–)2–6 mm, margins usually entire, rarely denticulate, (sometimes ciliate), surfaces sometimes pubescent with stellate to subdendritic, 4–12-rayed, (non-crisped) trichomes, 0.1–0.4 mm, (midvein persistent, prominent, strongly thickened).
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 (or, rarely, 1 as a bract).
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.

2–8(–12)-flowered, ebracteate, elongated in fruit;

rachis not flexuous, usually glabrous, rarely sparsely pubescent as stem basally.
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, 1.8–3 mm, usually glabrous, rarely sparsely pubescent subapically, (trichomes simple);

petals white, obovate, 3–5 × 1.8–3 mm;

anthers ovate, 0.3–0.4 mm.
Fruiting pedicels

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

divaricate-ascending, straight, (1–)2–5(–10) mm, glabrous.
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 elliptic-lanceolate or ovate to broadly so, plane, flattened, 4–8 × (1.5–)2–3 mm;

valves glabrous;

ovules (10–)14–22(–26) per ovary;

style 0.1–0.4 mm.
Seeds

oblong, 0.9–1.3 × 0.5–0.7 mm.

ovoid, 0.8–1.1 × 0.5–0.6 mm.
2n

= 74.

= 32, 48.

Draba aurea

Draba lactea
Phenology Flowering Jun–Aug. Flowering Jun–Aug.
Habitat Rock outcrops, talus, damp gullies and meadows, subalpine conifer woodlands, alpine slopes and turf, tundra, road banks, river gravel Rock outcrops, talus, rocky hillsides and ridges, open gravelly areas, seepage swales, meadows
Elevation (0-)700-4200 m ((0-)2300-13800 ft) 0-2000 m (0-6600 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; NL; NT; NU; QC; YT; Greenland; Europe (n Finland, Norway, w Sweden); Asia (Russian Far East, c, n Siberia); Atlantic Islands (Iceland); circumpolar
[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.)

T. W. Böcher (1966) postulated that Draba lactea originated from hybridization between D. fladnizensis and D. nivalis, but A.-C. Scheen et al. (2002) showed that it is more closely allied to D. subcapitata. By contrast, H. H. Grundt et al. (2004) concluded that hexaploid D. lactea originated from tetraploids of the same species, which in turn originated from the diploid D. palanderiana lineage. They suggested that D. lactea probably originated multiple times in the Beringian area and migrated to reach its present circumpolar distribution. The hexaploids are distributed throughout the species range, whereas the tetraploids are known only from Alaska and the Russian Far East (Grundt et al. 2005b).

Draba fernaldiana, which was collected from Southampton Island (Nunavut), was not mentioned by R. C. Rollins (1993). The plants are completely glabrous except for leaf margins, which are ciliate with simple and sparse 2-rayed trichomes. The taxon resembles some forms of D. lactea and is tentatively herein included within that species. The only conflict in such placement is petal color, which was listed in the original description of D. fernaldiana as pale yellow instead of white.

Glabrous or glabrescent forms of Draba lactea are quite common in the Canadian Arctic Archipelago, whereas pubescent forms predominate in Alaska and the Russian Far East.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 7, p. 294. FNA vol. 7, p. 316.
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. 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. 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. allenii, D. boecheri, D. fernaldiana
Name authority Vahl ex Hornemann: Fors. Oecon. Plantel. ed. 2, 599. (1806) Adams: Mém. Soc. Imp. Naturalistes Moscou 5: 104. (1817)
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).



Type/paste one or more Latin names into the boxes above; matching taxa will show up below the box as you type. You can use the up/down arrow keys to move through the list.

(If the plant you're looking for doesn't show up in the auto-complete list, that means it either isn't described in Flora of North America yet, or it's listed under a synonym. And please note that Flora of North America is still missing several plant families, including Fabaceae, Apiaceae, Boraginaceae, and Polemoniaceae.)

Choose a data source: Flora of North America, UW Burke Herbarium

The species comparison tool is brought to you by:
Northwest Wildflowers