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small-leaf bittercress

hairy bitter-cress, shotweed

Habit Perennials; usually glabrous, rarely sparsely hirtellous. Annuals; sparsely hirsute basally (at least on petiole of basal leaves), often glabrous distally.
Rhizomes

cylindrical, slender, 0.7–1.5 mm diam.

absent.

Stems

erect or ascending, unbranched, 0.3–1.5(–2) dm.

erect, ascending, or decumbent, unbranched or branched basally and/or distally, (0.3–)1–3.5(–4.5) dm, (not flexuous).

Basal leaves

(persistent to anthesis), rosulate, (5–)8–15(–22)-foliolate, (2–)3.5–15(–17) cm, leaflets petiolulate;

petiole 0.5–5 cm, (ciliate);

lateral leaflet blade oblong, ovate, obovate, or orbicular, smaller than terminal, margins entire, repand, crenate, or 3-lobed;

terminal leaflet (petiolule 0.2–1 cm), blade reniform or orbicular, 0.4–2 cm × 6–30 mm, margins entire, repand, dentate, or 3 or 5-lobed.

Rhizomal leaves

pinnately 5 or 7-foliolate, (1.3–)2.5–6.5 cm, (not fleshy), leaflets petiolulate;

petiole (0.5–)1.5–5.5 cm;

lateral leaflets similar to terminal, blade sometimes smaller;

terminal leaflet (petiolule 0.15–0.7 cm), blade ovate to elliptic, (0.2–)0.4–1.2(–1.5) cm × (1–)2.5–6 mm, base cuneate to obtuse, margins entire, (apiculate).

Cauline leaves

1–3, 5 or 7-foliolate, petiolate, leaflets petiolulate or subsessile;

petiole 0.2–1.5 cm, base not auriculate;

lateral leaflets similar to terminal;

terminal leaflet (subsessile or petiolule to 0.2 cm), blade ovate to elliptic, 0.6–1.3 × 0.1–0.7 cm, base cuneate, margins entire.

1–4(–6), compound as basal, petiolate, [(0.5–)1.2–5.5(–7) cm, including petiole], leaflets petiolulate;

blade base not auriculate;

leaflets similar to basal.

Racemes

ebracteate.

ebracteate.

Flowers

sepals ovate to oblong, 3–4 × 1.8–2.5 mm, lateral pair slightly saccate basally;

petals usually white, rarely lavender, broadly obovate, 7–10 × 3–6 mm, (clawed, apex rounded);

filaments: median pairs 3–4.5 mm, lateral pair 2–3 mm;

anthers oblong, 1–1.5 mm.

sepals oblong, 1.5–2.5 × 0.3–0.7 mm, lateral pair not saccate;

petals (sometimes absent) white, spatulate, 2.5–4.5(–5) × 0.5–1.1 mm; (stamens usually 4, lateral pair often absent, rarely 5 or 6);

filaments 1.8–3 mm;

anthers ovate, 0.3–0.5 mm.

Fruiting pedicels

erect to ascending, 7–15(–25) mm.

erect to ascending, (2–)3–10(–14) mm.

Fruits

linear, 2–3 cm × 1.2–1.7 mm;

ovules 12–16 per ovary;

style 1–2 mm.

linear, (torulose), (0.9–)1.5–2.5(–2.8) cm × (0.8–)1–1.4 mm, (often appressed to rachis);

ovules 14–40 per ovary;

style 0.1–0.6(–1) mm.

Seeds

brown, oblong, ca. 1.5 × 1 mm.

light brown, oblong or subquadrate, 0.9–1.3(–1.5) × 0.6–0.9(–1.1) mm, (narrowly margined).

2n

= 28, 42, 64.

= 16.

Cardamine microphylla

Cardamine hirsuta

Phenology Flowering Jul–Aug. Flowering Feb–Jul.
Habitat Streamsides, sand and cobbles on gravel bars, shale banks, floodplains, alluvial sand between cobbles, moist moss, turf, seepage areas, meadows, wet grounds Roadsides, clearings, disturbed sites, slopes, cedar glades, mixed woods, meadows, fields, waste grounds, damp places, grassy areas
Elevation 0-1600 m (0-5200 ft) 0-700 m (0-2300 ft)
Distribution
from FNA
AK; NT; YT; e Asia (Russian Far East, Siberia)
[BONAP county map]
from FNA
AL; AR; CA; CT; DC; DE; FL; GA; IL; KY; LA; MA; MD; MI; MO; MS; NC; NJ; NY; OH; OK; OR; PA; SC; TN; TX; UT; VA; WA; WV; BC; ON; w Eurasia [Introduced in North America; introduced also in Central America, South America, e Asia (Japan), South Africa, Australia]
[WildflowerSearch map]
[BONAP county map]
Discussion

Herbarium specimens of Cardamine hirsuta have been misidentified as C. oligosperma.

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

Source FNA vol. 7, p. 477. FNA vol. 7, p. 475.
Parent taxa Brassicaceae > tribe Cardamineae > Cardamine Brassicaceae > tribe Cardamineae > Cardamine
Sibling taxa
C. angulata, C. angustata, C. bellidifolia, C. blaisdellii, C. breweri, C. bulbosa, C. californica, C. clematitis, C. concatenata, C. constancei, C. cordifolia, C. digitata, C. diphylla, C. dissecta, C. douglassii, C. flagellifera, C. flexuosa, C. hirsuta, C. holmgrenii, C. impatiens, C. longii, C. macrocarpa, C. maxima, C. micranthera, C. nuttallii, C. nymanii, C. occidentalis, C. oligosperma, C. pachystigma, C. parviflora, C. pattersonii, C. penduliflora, C. pensylvanica, C. pratensis, C. purpurea, C. rotundifolia, C. rupicola, C. umbellata
C. angulata, C. angustata, C. bellidifolia, C. blaisdellii, C. breweri, C. bulbosa, C. californica, C. clematitis, C. concatenata, C. constancei, C. cordifolia, C. digitata, C. diphylla, C. dissecta, C. douglassii, C. flagellifera, C. flexuosa, C. holmgrenii, C. impatiens, C. longii, C. macrocarpa, C. maxima, C. micranthera, C. microphylla, C. nuttallii, C. nymanii, C. occidentalis, C. oligosperma, C. pachystigma, C. parviflora, C. pattersonii, C. penduliflora, C. pensylvanica, C. pratensis, C. purpurea, C. rotundifolia, C. rupicola, C. umbellata
Synonyms C. minuta
Name authority Adams: Mém. Soc. Imp. Naturalistes Moscou 5: 111. (1817) Linnaeus: Sp. Pl. 2: 655. (1753)
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