Flora of North America species comparison

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Draba brachycarpa

Draba pilosa

short-pod whitlowgrass, shortfruit Draba, shortpod Draba
Habit Annuals; not scapose. Perennials; (not stoloniferous); caudex branched (covered with persistent, dry leaves and midveins); scapose.
Stems

usually branched, rarely unbranched, (0.3–)0.4–1.9(–2.2) dm, pubescent throughout, trichomes sessile, cruciform, 0.2–0.6(–0.8) mm (rays often equal, or those parallel to stem axis longer).

unbranched, 0.4–1.7 dm, glabrous or pubescent, trichomes simple, 0.2–0.9 mm, and fewer, 2–4-rayed, 0.1–0.6 mm.
Basal leaves

not rosulate; petiolate;

petiole (to 0.5 cm), not ciliate;

blade oblanceolate to obovate, 0.5–2 cm × 2–8 mm, margins entire, surfaces pubescent, trichomes cruciform, 0.2–0.6(–0.8) mm.

(imbricate); rosulate; petiolate;

petiole (base thickened), ciliate throughout;

blade linear to linear-oblanceolate, 0.5–1.5(–2.2) cm × 1–2.5(–4) mm, margins entire (thickened, ciliate, trichomes simple and 2-rayed, to 1.1 mm), surfaces pubescent, abaxially with simple trichomes, 0.3–1 mm, and 2–4-rayed ones, 0.1–0.5 mm, adaxially similar, or with only simple trichomes, (midvein prominent, thickened).
Cauline leaves

(4–)6–11;

sessile;

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

0.
Racemes

(main branch) (20–)25–65(–74)-flowered, ebracteate, elongated in fruit;

rachis not flexuous, pubescent as stem.

(2–)4–12-flowered, ebracteate, usually elongated in fruit;

rachis not flexuous, glabrous or pubescent as stem.
Flowers

(late ones cleistogamous, apetalous);

sepals (green or pink), oblong, 0.7–1.2(–1.5) mm, pubescent;

petals white, spatulate, 2–3 × 0.8–1.1 mm;

anthers ovate, 0.15–0.25 mm.

sepals ovate, 2–3.5 mm, pubescent, (trichomes simple and short-stalked, 2-rayed);

petals pale to bright yellow, obovate, 3.5–6 × 2–3.5 mm;

anthers ovate, 0.4–0.5 mm.
Fruiting pedicels

horizontal to divaricate-ascending, straight, (1–)1.5–4(–5) mm, pubescent, trichomes cruciform.

divaricate-ascending, usually straight, rarely curved upward, 6–13 mm, glabrous or pubescent as stem.
Fruits

usually elliptic to linear-elliptic, rarely ovate-elliptic, plane, flattened, (2–)2.5–5(–6) × 0.9–1.4(–1.9) mm;

valves glabrous;

ovules 8–16(–20) per ovary;

style 0.05–0.1 mm.

elliptic to lanceolate, 5–11 × 3–4 mm, plane, flattened;

valves glabrous or puberulent with simple and short-stalked, 2-rayed trichomes, 0.07–0.3 mm;

ovules 12–20 per ovary;

style 0.4–0.9 mm (stigma about as wide as style).
Seeds

(winged), ovoid, 0.5–0.7 × 0.4–0.5 mm.

ovoid, 1.2–1.4 × 0.8–1 mm.
2n

= 16.

Draba brachycarpa

Draba pilosa
Phenology Flowering Feb–May. Flowering Jul–Aug.
Habitat Open woods, cedar glades, pastures and lawns, roadsides, disturbed sites Dry gravelly slopes, sandy places, wet tundra
Elevation 0-300 m (0-1000 ft) 0-1300 m (0-4300 ft)
Distribution
from FNA
AL; AR; AZ; FL; GA; IL; IN; KS; KY; LA; MO; MS; NC; OH; OK; OR; SC; TN; TX; VA
[WildflowerSearch map]
[BONAP county map]
from FNA
AK; NT; NU; YT; e Asia (ne Russian Far East, n Siberia)
[BONAP county map]
Discussion

Draba brachycarpa is closely related to D. aprica and the two are sometimes confused. It is readily distinguished by having leaves with sessile (versus stalked) trichomes, glabrous (versus pubescent) fruits, and smaller (0.5–0.7 versus 0.9–1.1 mm) seeds.

The records from Arizona and Oregon are based on old collections, Porter 802 (Devil’s Canyon, 22 Feb 1926, US) and Howell s.n. (near Cobarg, Willamette Valley, 7 Apr 1887, US); it is not known if these records represent introductions or remnants of a previously wider distribution.

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

O. E. Schulz (1927) reduced Draba pilosa to a variety of the decaploid D. alpina and cited North American collections. The former species was not listed by C. L. Hitchcock (1941) or R. C. Rollins (1993). From D. alpina, D. pilosa is easily distinguished by having strongly thickened and persistent (versus not thickened) midveins and margins, and usually narrower leaf blades [1–2.5(–5) versus 2.5–6(–9) mm wide].

As recognized herein, Draba pilosa is broadly circumscribed to include perhaps two or three closely related taxa. All are scapose plants with large, yellow flowers and prominent, persistent midveins and petioles. Some Alaskan forms (e.g., Parker 7596, ALA), which grow in moist heath habitats, have leaves 3–5 mm wide, whereas the majority have narrower leaf blades rarely reaching 2.5 mm in width. Most plants assigned to this species have leaves with exclusively simple trichomes and often glabrous scapes. Others (e.g., Chesemore & Davies 13, Murray 3371, Parker & Batten 8954, all at ALA) have leaf blade surfaces and scapes with 2–4-rayed trichomes and blade margins ciliate with simple trichomes. One collection (Walker s.n., ALA) has a mixture of plants of both trichome types but no intermediates were found. Detailed molecular and cytological studies are needed on this complex to determine if more than one taxon is represented.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 7, p. 296. FNA vol. 7, p. 330.
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. 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. 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 Abdra brachycarpa D. alpina var. pilosa, D. aspera
Name authority Nuttall ex Torrey & A. Gray: Fl. N. Amer. 1: 108. (1838) Adams ex de Candolle: in A. P. de Candolle, Syst. Nat. 2: 336. (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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