Flora of North America species comparison

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Draba norvegica

Draba borealis

Norwegian Draba

boreal Draba, northern Draba, northern whitlow-grass
Habit Perennials; (cespitose); caudex branched (sometimes with persistent leaf remains); often scapose. Perennials; caudex branched (branches usually slender, elongated, rhizomatous, sometimes with persistent leaf bases); not scapose.
Stems

branched or unbranched, (0.2–)0.4–1.4(–2) dm, pubescent throughout, trichomes simple and 2–4-rayed, 0.2–0.5 mm.

usually unbranched, rarely branched, (0.4–)1–3.6(–5.5) dm, often hirsute proximally, trichomes usually simple and 2-rayed, 0.5–1.1 mm, with short-stalked, 3–8-rayed ones, 0.1–0.4 mm (rarely simple trichomes absent distally).
Basal leaves

rosulate;

petiolate;

petiole (0–0.5 cm), ciliate throughout;

blade oblanceolate to narrowly obovate or narrowly lanceolate, 0.4–2.1 cm × 1.5–7 mm, margins with 1–3 teeth on each side, (ciliate, trichomes simple and 2-rayed, 0.2–0.8 mm), surfaces pubescent abaxially with stalked, (2–)4(–6)-rayed trichomes, 0.1–0.4 mm, adaxially glabrous or pubescent, with simple and stalked, 2-rayed trichomes, 0.1–0.5 mm.

rosulate;

blade ovate or obovate to oblanceolate, (0.5–)1–4.2(–6) cm × 3–10(–25) mm, margins dentate or denticulate, surfaces pubescent, trichomes short-stalked, cruciform, or (2–)4–6-rayed, 0.2–0.6 mm (principal rays usually simple, rarely 1 or 2 with a lateral branch, sometimes appearing to 10-rayed).
Cauline leaves

0–3(–5);

sessile;

blade ovate to oblong, margins often dentate, (ciliate).

(2 or) 3–7(–12);

sessile;

blade ovate, margins entire or dentate, surfaces pubescent as basal or adaxially with some simple trichomes.
Racemes

5–23-flowered, ebracteate or proximalmost 1(–3) flowers bracteate, considerably elongated in fruit;

rachis slightly or not flexuous, pubescent as stem.

(6–)8–20(–35)-flowered, ebracteate, elongated in fruit;

rachis not flexuous, pubescent as stem.
Flowers

sepals ovate, 1.7–2.5 mm, pubescent, (trichomes simple and short-stalked, 2–4-rayed);

petals white, spatulate, 2.5–4 × 1.7–2.5 mm;

anthers ovate, 0.3–0.4 mm.

sepals ovate, 2–3 mm, pubescent, (trichomes simple);

petals white, obovate, 4–6 × 2–3 mm;

anthers ovate, 0.3–0.5 mm.
Fruiting pedicels

suberect to ascending (often appressed to rachis), straight, (1.5–)2.5–5(–9) mm, pubescent, trichomes simple and 2–4-rayed.

divaricate or ascending, straight, (2–)4–8(–13) mm, pubescent as stem.
Fruits

(sometimes subappressed to rachis), oblong to lanceolate-elliptic, plane, flattened, 4–8 × 2–3 mm;

valves glabrous or pubescent, trichomes simple and short-stalked, 2-rayed, 0.05–0.25 mm;

ovules 18–26 per ovary;

style (0.01–)0.1–0.4(–0.5) mm, (glabrous, stigma about as wide as style).

ovate to broadly oblong or lanceolate, slightly twisted or plane, flattened, (5–)7–12 × 2.5–4.5 mm;

valves pubescent, trichomes simple and short-stalked, 2–4-rayed, 0.1–0.4 mm;

ovules 16–28(–30) per ovary;

style 0.2–0.6(–0.8) mm, glabrous.
Seeds

oblong, 0.9–1.2 × 0.5–0.7 mm.

oblong, 1–1.5 × 0.7–1 mm.
2n

= 48.

= 64, 80.

Draba norvegica

Draba borealis
Phenology Flowering Jun–Aug. Flowering Jun–Jul.
Habitat Rock outcrops and sea cliffs, talus, gravelly and sandy terraces, moist bluffs, turfy limestone shores Rock outcrops and talus, gravelly terraces, meadows, forest edges and thickets, roadsides, grassy areas, alpine tundra
Elevation 0-500 m (0-1600 ft) 0-2400 m (0-7900 ft)
Distribution
from FNA
NL; NS; NT; QC; Greenland; Europe (Finland, Norway, n Russia, Scotland, Sweden); Atlantic Islands (Iceland)
[BONAP county map]
from FNA
AK; AB; BC; NT; NU; YT; e Asia (Japan, Russian Far East)
[BONAP county map]
Discussion

Draba norvegica is a highly variable hexaploid taxon and, as delimited herein, it probably represents two taxa with the same distribution and same chromosome number. It is related to hexaploid D. arctogena, from which it is distinguished by characteristics listed under 8. D. arctogena.

Draba norvegica was divided by O. E. Schulz (1927) into eight varieties, whereas R. C. Rollins (1993) recognized just two. In the latter treatment, var. clivicola is distinguished by having predominantly branched, appressed trichomes on stems proximally, lanceolate, glabrous fruits, and slender, erect-appressed pedicels. By contrast, var. norvegica is said to have predominantly simple, spreading trichomes on stems proximally, narrowly ovate to elliptical, glabrous or pubescent fruits, and stout, divaricately ascending pedicels. These differences are extremes of a continuum, and we agree with G. A. Mulligan (1970) in reducing D. clivicola to synonymy of D. norvegica. Rollins indicated that D. norvegica grows in Minnesota, but we have not seen any material from that state.

Draba norvegica is found in Europe in arctic and subarctic areas.

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

Draba borealis is highly variable in leaf and stem indumentum, leaf shape and margin, number of cauline leaves, and fruit shape, size, and twisting. North American plants yielded decaploid chromosome counts; octoploid populations were reported from the Russian Far East. This suggests that more than one taxon is present, and the species is much in need of detailed molecular, cytogenetic, and morphological study.

In the absence of flowers, Draba borealis is occasionally confused with some forms of D. aurea. The latter usually has proximally bracteate (versus ebracteate) racemes, generally longer styles [0.5–1.5(–1.7) versus 0.2–0.6(–0.8) mm], and more ovules [28–38(–44) versus 16–28(–30)] per ovary. Draba borealis occasionally is confused with D. glabella, but the latter has pectinate-stellate trichomes on abaxial leaf blade surfaces. R. C. Rollins (1993) indicated that D. borealis occurs in Colorado, but we have not seen any material from the United States outside of Alaska.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 7, p. 322. FNA vol. 7, p. 296.
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. nivalis, 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. 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
Synonyms D. clivicola, D. hirta var. norvegica, D. norvegica var. clivicola, D. norvegica var. hebecarpa, D. rupestris, D. scandinavica var. hebecarpa, D. trichella D. borealis var. maxima, D. maxima, D. unalaschkiana
Name authority Gunnerus: Fl. Norveg. 2: 106. (1772) de Candolle: Syst. Nat. 2: 342. (1821)
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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