Flora of North America species comparison

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Draba incerta

Draba juvenilis

whitlow-wort, Yellowstone Draba, Yellowstone Draba whitlow-wort, Yellowstone whitlow-grass, Yellowstone whitlow-wort

long-stalk Draba, long-stalk whitlow-grass
Habit Perennials; (cespitose, often pulvinate); caudex branched (dense with persistent leaf remains, branches sometimes terminating in sterile rosettes); scapose. Perennials; (not pulvinate); caudex branched (branches slightly loose, with persistent leaf remains, sometimes terminating in sterile rosettes); often scapose.
Stems

unbranched, (0.2–)0.4–1.4(–2.1) dm, often pubescent throughout, sometimes glabrous distally, trichomes often simple and 2–5-rayed, 0.1–0.5 mm, (sometimes with mostly subpectinate ones).

unbranched, (0.3–)0.8–2.3(–3) dm, pubescent proximally, glabrous or sparsely pubescent distally, trichomes simple and 2–4-rayed, 0.07–0.4 mm.
Basal leaves

rosulate; petiolate;

petiole (0–1 cm), ciliate throughout;

blade narrowly oblanceolate to linear, (0.4–)0.6–1.7(–2.5) cm × (1–)1.5–3.5(–5) mm, margins entire, (ciliate, trichomes usually simple, rarely 2-rayed, 0.2–1.1 mm), surfaces usually pubescent with short-stalked, pectinate trichomes, 0.15–0.5 mm, sometimes also with 4–6-rayed ones, (midvein usually obscure abaxially), sometimes glabrous adaxially.

(loosely) rosulate; petiolate;

petiole base ciliate, margin not ciliate, (midvein obscure, trichomes simple and 2-rayed, 0.2–0.7 mm);

blade oblanceolate to lanceolate, (0.3–)0.6–2.5(–3.5) cm × (1–)2–7(–10) mm, margins entire or denticulate, surfaces pubescent, abaxially with stalked, cruciform trichomes, 0.2–0.5 mm, adaxially with cruciform and/or simple and 2-rayed ones.
Cauline leaves

usually 0 (or 1, as a bract);

sessile;

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

0–2 (or 3);

sessile;

blade elliptic to ovate or lanceolate, margins usually entire, rarely denticulate, surfaces pubescent as basal adaxially or trichomes predominantly simple.
Racemes

3–14(–30)-flowered, usually ebracteate, rarely proximalmost flowers bracteate, elongated in fruit;

rachis not flexuous, glabrous or pubescent as stem.

(2–)4–13(–18)-flowered, ebracteate, elongated in fruit;

rachis not flexuous, glabrous or sparsely pubescent as stem.
Flowers

sepals broadly ovate, 2.5–3.5(–4) mm, pubescent, (trichomes simple and 2- or 3-rayed);

petals yellow (fading white), oblanceolate to obovate, 4–6 × 1.5–2.5 mm;

anthers ovate, 0.3–0.5 mm.

sepals ovate, 2.2–3 mm, glabrous or pubescent subapically, (trichomes simple and short-stalked, 2-rayed);

petals pale yellow to creamy white, spatulate, 3–5 × 1.5–2.5 mm;

anthers ovate, 0.4–0.5 mm.
Fruiting pedicels

ascending, straight, (2.5–)4–11(–27) mm, glabrous or pubescent, trichomes 2–5-rayed or pectinate.

divaricate-ascending or ascending, straight or often curved upward (not expanded basally), (3–)5–17(–22) mm, usually glabrous, rarely pubescent, trichomes simple and stalked, 2–4-rayed.
Fruits

broadly ovate to lanceolate, plane, flattened, 5–9(–11) × 2–4 mm;

valves glabrous or puberulent, trichomes simple and 2-rayed, 0.05–0.3 mm;

ovules 8–16(–20) per ovary;

style 0.2–0.9 mm.

elliptic to oblong or linear-lanceolate, plane (not curved), flattened, 5–11(14) × 2–3 mm;

valves usually glabrous, rarely margin pubescent, trichomes simple;

ovules 16–30 per ovary;

style 0.2–0.7 mm.
Seeds

oblong, 1.1–1.5 × 0.7–1 mm.

oblong, 0.7–1.2(–1.5) × 0.4–0.7(–0.8) mm.
2n

= 112.

= 64.

Draba incerta

Draba juvenilis
Phenology Flowering Jun–Aug. Flowering Jun–Jul.
Habitat Rock outcrops, talus, gravelly areas, tundra Rock outcrops, talus, gravelly beaches and stream banks, meadows, tundra
Elevation 0-3300 m (0-10800 ft) 0-2700 m (0-8900 ft)
Distribution
from FNA
AK; CO; ID; MT; NV; UT; WA; WY; AB; BC; QC; YT
[WildflowerSearch map]
[BONAP county map]
from FNA
AK; AB; BC; NT; YT; e Asia (Russian Far East, n Siberia)
[BONAP county map]
Discussion

Draba incerta was shown by G. A. Mulligan (1972) to be sexually reproducing and 14-ploid with x = 8. It is often confused with the apomict D. oligosperma (2n = 32, 64). Draba incerta is readily separated from D. oligosperma by having well-formed (versus abortive) anthers and pollen, stalked (versus sessile) leaf trichomes, and ciliate (versus non-ciliate) basal leaves with obscure (versus prominent) midveins. Although both species have leafless scapes, one often finds a bract adnate to, or subtending, the proximalmost pedicel in D. incerta.

Draba incerta is found near sea level in Alaska.

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

Although Draba kananaskis and D. longipes have often been treated as distinct species, we find no basis for maintaining them. Both exhibit variations in petal color (white to pale yellow) and leaf trichomes (short-stalked to sessile) characteristic of D. juvenilis from the Russian Far East. Perhaps most importantly, all three are octoploids (2n = 64) with x = 8. We conclude that D. kananaskis is nothing more than a minor variant of D. juvenilis and it is treated herein, for the first time, as a synonym of that species.

Draba juvenilis is occasionally confused with D. borealis, which also has stalked, cruciform trichomes with unbranched rays. Typical D. juvenilis is easily distinguished from that species by having narrower (2–3 mm) fruits that are glabrous (rarely pubescent) and untwisted, and 0–2 (or 3)-leaved stems. By contrast, D. borealis has wider (2.5–4.5 mm) fruits that are usually pubescent and/or twisted (rarely neither) and (2 or) 3–7(–12)-leaved stems.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 7, p. 313. FNA vol. 7, p. 314.
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. 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. 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. exalata, D. incerta var. laevicapsula, D. incerta var. peasei, D. laevicapsula, D. peasei D. hirta var. tenella, D. kananaskis, D. longipes
Name authority Payson: Amer. J. Bot. 4: 261. (1917) Komarov: Repert. Spec. Nov. Regni Veg. 13: 167. (1914)
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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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