Flora of North America species comparison

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Draba albertina

Draba streptobrachia

Alaska Draba, Alaska whitlow-grass, Alberta whitlow grass, slender Draba, slender whitlow-grass

alpine tundra Draba
Habit Annuals, biennials, or perennials; caudex (or base) simple or branched (poorly developed); rarely scapose. Perennials; caudex branched (often with persistent leaf remains, branches not creeping); not scapose.
Stems

branched distally, (0.3–)0.5–3(–4.2) dm, pubescent proximally, often glabrous distally, trichomes simple, 0.1–1 mm, sometimes with fewer, stalked, 2-rayed ones.

unbranched, (0.1–)0.2–1(–1.3) dm, pubescent throughout, trichomes subsessile (often crisped), 3–5-rayed, stellate, 0.03–0.25(–0.4) mm, (rays sometimes forked).
Basal leaves

rosulate; shortly petiolate;

petiole (0–0.5 cm), ciliate throughout;

blade obovate to oblanceolate or linear-lanceolate, (0.3–)1–2.8(–3.5) cm × (1–)2–6(–9) mm, margins entire or denticulate, (ciliate, trichomes simple, 0.4–1 mm), surfaces usually pubescent, abaxially with stalked, 2–4-rayed trichomes, 0.05–0.4(–0.5) mm, (rarely with simple trichomes along midvein), adaxially with simple trichomes sometimes also with 2-rayed ones, 0.07–0.4 mm, rarely glabrous.

rosulate;

petiole (obscure), usually not ciliate, rarely sparsely pubescent, (trichomes simple, to 0.6 mm);

blade oblanceolate to linear-oblanceolate, (0.4–)0.5–3(–4) cm × 1–5 mm, margins entire, surfaces pubescent with short-stalked (crisped), 3–8-rayed trichomes, 0.05–0.4 mm.
Cauline leaves

(0 or) 1–3(–5);

sessile;

blade lanceolate to elliptic or ovate, margins entire or denticulate, surfaces pubescent as basal.

(1 or) 2–4 (or 5);

sessile;

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

(2–)6–30(–50)-flowered, ebracteate, elongated in fruit;

rachis straight or, rarely, flexuous, glabrous.

4–10(–18)-flowered, ebracteate, elongated in fruit;

rachis not flexuous, pubescent as stem.
Flowers

(chasmogamous, petaliferous);

sepals ovate, 1.4–2.1 mm, glabrous or sparsely pubescent, (trichomes simple);

petals yellow, spatulate to oblanceolate, 2–3.2 × 0.7–1.2 mm;

anthers ovate, 0.15–0.25 mm.

sepals ovate, 2–3 mm, pubescent, (trichomes simple and short-stalked, 2–4-rayed);

petals yellow, spatulate, 3–5 × 1.5–3 mm, (clawed);

anthers ovate, 0.25–0.4 mm.
Fruiting pedicels

divaricate-ascending or horizontal, (not appressed to rachis), usually straight, rarely curved upward, (3–)5–14(–16) mm (subequaling or shorter than fruit), usually glabrous, rarely sparsely puberulent.

ascending, usually straight, rarely curved upward, (2–)3–8(–12) mm, pubescent as stem.
Fruits

lanceolate to narrowly elliptic or linear, plane, flattened, (4–)6–12(–15) × (1–)1.4–2.1 mm;

valves glabrous;

ovules (20–)24–38(–44) per ovary;

style 0.01–0.12 mm.

(not appressed to rachis), ovate to elliptic or lanceolate, slightly twisted or plane, flattened, (3–)5–10 × 2–4 mm;

valves often pubescent, occasionally glabrous, trichomes simple and minutely stalked, 2–4-rayed, 0.03–0.25 mm;

ovules 10–16(–18) per ovary;

style 0.3–0.8(–1.2) mm.
Seeds

oblong, 0.7–1 × 0.4–0.5 mm.

oblong, 1–1.6 × 0.6–1 mm.
2n

= 24.

= ca. 64.

Draba albertina

Draba streptobrachia
Phenology Flowering Jun–Aug. Flowering Jul–Aug.
Habitat Open woodlands, pine forests, meadows, rocky knolls, alpine slopes, stream banks, disturbed areas Alpine tundra, scree, ridges and alpine slopes, turf, fellfields, talus slopes, crevices in rock ledges, loose soils
Elevation 900-3700 m (3000-12100 ft) 3200-4000 m (10500-13100 ft)
Distribution
from FNA
AK; AZ; CA; CO; ID; MT; NM; NV; OR; UT; WA; WY; AB; BC; NT; YT
[WildflowerSearch map]
[BONAP county map]
from FNA
CO
[WildflowerSearch map]
[BONAP county map]
Discussion

O. E. Schulz (1927) and C. L. Hitchcock (1941) confused the limits of Draba albertina, D. crassifolia, and D. stenoloba; the latter author treated the first two species as conspecific. G. A. Mulligan (1975) demonstrated that the three taxa are chromosomally and morphologically distinct (see D. crassifolia and D. stenoloba for differences from D. albertina). The ranges of D. albertina and D. crassifolia overlap extensively, and occasional sterile hybrids are encountered.

The Alaskan record of Draba albertina is based on Minard 4 (ALA), collected on the northern coast of Afognak Island (58°22’N, 152°28’W). The record from New Mexico is based on O’Kane & Hedin 3871 (ISTC, SJC), collected in Chuska Mountains (36°8’11”N, 108°54’19”W).

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

As indicated by Price, Draba streptobrachia is an apomict, yielding abundant, well-developed seed despite producing only abortive pollen. Morphological studies (M. D. Windham, unpubl.) suggest that the species may be an allopolyploid containing a genome from D. crassa.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 7, p. 288. FNA vol. 7, p. 341.
Parent taxa Brassicaceae > tribe Arabideae > Draba Brassicaceae > tribe Arabideae > Draba
Sibling taxa
D. abajoensis, 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. 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. standleyi, D. stenoloba, D. stenopetala, D. streptocarpa, D. subalpina, D. subcapitata, D. subumbellata, D. trichocarpa, D. ventosa, D. verna, D. viridis, D. weberi, D. yukonensis, D. zionensis
Synonyms D. crassifolia var. albertina, D. crassifolia var. nevadensis, D. deflexa, D. nitida, D. nitida var. nana, D. stenoloba var. nana, D. stenoloba var. ramosa D. chrysantha, D. spectabilis var. dasycarpa
Name authority Greene: Pittonia 4: 312. (1901) R. A. Price: Brittonia 32: 168. (1980)
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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