OregonFlora: Draba aurea vs. Draba oligosperma

	Draba aurea	Draba oligosperma
		few-seeded whitlow-grass
Habit		Plants perennial, cespitose, densely pulvinate, scapose; caudices many-branched, some branches terminated in sterile rosettes.
Stems		(1)2–6(10) cm, unbranched, glabrous or with sessile, pectinate trichomes.
Basal leaves		rosulate, linear to linear-oblanceolate; (2)4–11(15) × 0.4–1.5(1.8) mm; margins entire; midveins prominent abaxially; surfaces pubescent with sessile, pectinate trichomes, adaxially sometimes glabrous, rarely ciliate, sessile.
Cauline leaves		absent.
Inflorescences		4–12(17)-flowered; rachises straight, fruiting pedicels divaricate-ascending; straight; (2)3–10(13) mm, glabrous or pubescent; bracts 0.
Flowers		sepals ovate, 1.5–3 mm, glabrous or pubescent; petals obovate, 2.5–4 × 1.5–3 mm, yellow or rarely creamy white; ovules 6–12 per ovary; styles 0.1–0.8(1.1) mm.
Fruits		ovoid to lanceolate, inflated at least basally, untwisted, 3–6(7) × 2–3.5(4) mm, puberulent with simple and sessile, often unequally 2-rayed trichomes, rarely glabrous.
Seeds		ovoid, flattened, 1.1–1.5 × 0.7–1 mm; wingless.
2n		=32, 64.

	Draba aurea	Draba oligosperma
Distribution	[WildflowerSearch map] [BONAP county map]	[WildflowerSearch map] [BONAP county map]
Discussion		Talus, rock outcrops, gravel benches. Flowering May–Jul. 2400–3000 m. BW. CA, ID, NV, WA; north to AK, northeast to MT, east to WY, southeast to CO. Native. This apomictic, pulvinate species is easily distinguished from other North American species by its pectinate trichomes, prominent midveins on basal leaves, and basally inflated fruits.
Source		Flora of Oregon, volume 2, page 481 Ihsan Al-Shehbaz
Sibling taxa	D. albertina, D. aureola, D. cana, D. crassifolia, D. cusickii, D. cyclomorpha, D. densifolia, D. howellii, D. incerta, D. lonchocarpa, D. nemorosa, D. novolympica, D. oligosperma, D. praealta, D. stenoloba, D. verna	D. albertina, D. aureola, D. cana, D. crassifolia, D. cusickii, D. cyclomorpha, D. densifolia, D. howellii, D. incerta, D. lonchocarpa, D. nemorosa, D. novolympica, D. praealta, D. stenoloba, D. verna
Synonyms		Draba oligosperma var. oligosperma
Web links	Local floras: BC, WA Local Web sites: Flora NW, PNW Herbaria WildflowerSearch iNaturalist (observations) USDA Plants Database LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search	Local floras: BC, CA, OR, WA Local Web sites: CalFlora, CalPhotos, Flora NW, PNW Herbaria WildflowerSearch iNaturalist (observations) USDA Plants Database LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search

Draba aurea

Draba oligosperma

few-seeded whitlow-grass

Habit

Plants perennial, cespitose, densely pulvinate, scapose; caudices many-branched, some branches terminated in sterile rosettes.

Stems

(1)2–6(10) cm, unbranched, glabrous or with sessile, pectinate trichomes.

Basal leaves

rosulate, linear to linear-oblanceolate; (2)4–11(15) × 0.4–1.5(1.8) mm;

margins entire;

midveins prominent abaxially;

surfaces pubescent with sessile, pectinate trichomes, adaxially sometimes glabrous, rarely ciliate, sessile.

Cauline leaves

absent.

Inflorescences

4–12(17)-flowered;

rachises straight, fruiting pedicels divaricate-ascending; straight; (2)3–10(13) mm, glabrous or pubescent;

bracts 0.

Flowers

sepals ovate, 1.5–3 mm, glabrous or pubescent;

petals obovate, 2.5–4 × 1.5–3 mm, yellow or rarely creamy white;

ovules 6–12 per ovary;

styles 0.1–0.8(1.1) mm.

Fruits

ovoid to lanceolate, inflated at least basally, untwisted, 3–6(7) × 2–3.5(4) mm, puberulent with simple and sessile, often unequally 2-rayed trichomes, rarely glabrous.

Seeds

ovoid, flattened, 1.1–1.5 × 0.7–1 mm; wingless.

=32, 64.

Draba aurea

Draba oligosperma

Distribution

[WildflowerSearch map]

[BONAP county map]

[WildflowerSearch map]

[BONAP county map]

Discussion

Talus, rock outcrops, gravel benches. Flowering May–Jul. 2400–3000 m. BW. CA, ID, NV, WA; north to AK, northeast to MT, east to WY, southeast to CO. Native.

This apomictic, pulvinate species is easily distinguished from other North American species by its pectinate trichomes, prominent midveins on basal leaves, and basally inflated fruits.

Source

Flora of Oregon, volume 2, page 481
Ihsan Al-Shehbaz

Sibling taxa