Burke: Lepidium didymum vs. Lepidium nitidum

	Lepidium didymum	Lepidium nitidum
	lesser swinecress, lesser wartcress	shining peppergrass
Habit	Low, spreading, glabrous to scurfy-pubescent annual, the stems freely-branched, decumbent, 2-5 dm. long.	Slender annual, the spreading to erect stems 1-4 dm. long, simple to freely-branched, mostly glabrous below, puberulent to pubescent above and throughout the inflorescence.
Leaves	Leaves alternate, numerous, ovate-oblong, 1.5-3 cm. long, pinnatifid, the segments narrow, entire to pinnatifid.	Leaves alternate, deeply pinnatified into 3-7 pairs of linear segments, the basal ones 3-10 cm. long, the cauline leaves gradually reduced, the upper ones sometimes entire.
Flowers	Inflorescence of many-flowered, crowded, axillary, bractless racemes 1-4 cm. long; pedicles slender, 1.5-2.5 mm. long; sepals 4, spreading, 0.5 mm. long, deciduous; petals 4, white, linear, minute; stamens 2.	Inflorescence of bractless, open and elongate racemes; pedicles strongly flattened, ascending; sepals 4, 1-1.5 mm. long; petals 4, white, 1-2 mm. long; stamens usually 6; style lacking.
Fruit(s)	Silicles strongly wrinkled, 2 mm. broad and 1.5 mm. long, cordate and notched, inflated and slightly obcompressed.	Silicles ovate to oblong-obicular, 3.5-4.5 mm. long, glabrous, lightly veined, both surfaces smooth and shining, the slightly winged margins upturned all the way around, the tip slightly notched.

	Lepidium didymum	Lepidium nitidum
Flowering time	May-July	March-April
Habitat	Roadsides, gardens and wasteland.	Dry, open areas at low elevation.
Distribution	Occurring west of the Cascades crest in Washington; British Columbia to California, Arizona, and Texas eastward and northward to the Atlantic Coast. [WildflowerSearch map] [BONAP county map]	Known from Klickitat County in Washington; south-central Washington to California. [WildflowerSearch map] [BONAP county map]
Origin	Introduced from South America (or possibly Eurasia)	Native
Conservation status	Not of concern	Not of concern
Sibling taxa	L. appelianum, L. campestre, L. chalepense, L. densiflorum, L. dictyotum, L. draba, L. heterophyllum, L. latifolium, L. nitidum, L. oblongum, L. oxycarpum, L. perfoliatum, L. ramosissimum, L. sativum, L. strictum, L. virginicum	L. appelianum, L. campestre, L. chalepense, L. densiflorum, L. dictyotum, L. didymum, L. draba, L. heterophyllum, L. latifolium, L. oblongum, L. oxycarpum, L. perfoliatum, L. ramosissimum, L. sativum, L. strictum, L. virginicum
Web links	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	Local floras: 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

Lepidium didymum

Lepidium nitidum

lesser swinecress, lesser wartcress

shining peppergrass

Habit

Low, spreading, glabrous to scurfy-pubescent annual, the stems freely-branched, decumbent, 2-5 dm. long.

Slender annual, the spreading to erect stems 1-4 dm. long, simple to freely-branched, mostly glabrous below, puberulent to pubescent above and throughout the inflorescence.

Leaves

Leaves alternate, numerous, ovate-oblong, 1.5-3 cm. long, pinnatifid, the segments narrow, entire to pinnatifid.

Leaves alternate, deeply pinnatified into 3-7 pairs of linear segments, the basal ones 3-10 cm. long, the cauline leaves gradually reduced, the upper ones sometimes entire.

Flowers

Inflorescence of many-flowered, crowded, axillary, bractless racemes 1-4 cm. long; pedicles slender, 1.5-2.5 mm. long;

sepals 4, spreading, 0.5 mm. long, deciduous;

petals 4, white, linear, minute;

stamens 2.

Inflorescence of bractless, open and elongate racemes; pedicles strongly flattened, ascending;

sepals 4, 1-1.5 mm. long;

petals 4, white, 1-2 mm. long;

stamens usually 6;

style lacking.

Fruit(s)

Silicles strongly wrinkled, 2 mm. broad and 1.5 mm. long, cordate and notched, inflated and slightly obcompressed.

Silicles ovate to oblong-obicular, 3.5-4.5 mm. long, glabrous, lightly veined, both surfaces smooth and shining, the slightly winged margins upturned all the way around, the tip slightly notched.