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small-leaf bittercress

American bittercress, mountain watercress

Habit Perennials; usually glabrous, rarely sparsely hirtellous. Perennials; glabrous throughout.
Rhizomes

cylindrical, slender, 0.7–1.5 mm diam.

slender, to 2 mm diam.

Stems

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

usually procumbent, sometimes erect, (not flexuous), unbranched or branched, (1–)1.5–3(–5) dm.

Basal leaves

(soon withered), not rosulate.

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).

absent.

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.

simple, petiolate;

petiole (0.3–)0.5–2.5(–4) cm, base not auriculate;

blade oblong, ovate, suborbicular, or cordate, (0.5–)1–4.5(–5.5) cm × (5–)10–40(–54) mm, base cordate, rounded, or truncate, margins entire, repand, or sinuate, (distally with shorter petiole, blade smaller).

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, 2–3 × 1–1.7 mm, lateral pair not saccate basally;

petals white, broadly oblanceolate, spreading, 5–7(–8) × 2–3 mm, (not clawed, apex rounded);

filaments: median pairs 3.5–4.5 mm, lateral pair 2.7–3.5 mm;

anthers oblong, 0.8–1.2 mm.

Fruiting pedicels

erect to ascending, 7–15(–25) mm.

divaricate to ascending, (6–)10–15(–20) mm.

Fruits

linear, 2–3 cm × 1.2–1.7 mm;

ovules 12–16 per ovary;

style 1–2 mm.

linear, (torulose), 1–1.5(–2) cm × 0.8–1.1 mm;

ovules 40–80 per ovary;

style 1.5–2.5 mm.

Seeds

brown, oblong, ca. 1.5 × 1 mm.

brown, oblong to ovoid, 0.9–1.1 × 0.5–0.6 mm.

2n

= 28, 42, 64.

Cardamine microphylla

Cardamine rotundifolia

Phenology Flowering Jul–Aug. Flowering Apr–Jun.
Habitat Streamsides, sand and cobbles on gravel bars, shale banks, floodplains, alluvial sand between cobbles, moist moss, turf, seepage areas, meadows, wet grounds Stream banks, swamps, low woodland, wet rocky areas, seepage areas
Elevation 0-1600 m (0-5200 ft) 150-400 m (500-1300 ft)
Distribution
from FNA
AK; NT; YT; e Asia (Russian Far East, Siberia)
[BONAP county map]
from FNA
DE; GA; KY; MD; NC; NJ; NY; OH; PA; TN; VA; WV
[WildflowerSearch map]
[BONAP county map]
Source FNA vol. 7, p. 477. FNA vol. 7, p. 483.
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. hirsuta, 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. rupicola, C. umbellata
Synonyms C. minuta Dentaria rotundifolia
Name authority Adams: Mém. Soc. Imp. Naturalistes Moscou 5: 111. (1817) Michaux: Fl. Bor.-Amer. 2: 30. (1803)
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