Cardamine rotundifolia
Cardamine flexuosa
American bittercress, mountain watercress
wavy bitter-cress, wood bitter-cress, woodland bitter-cress
slender, to 2 mm diam.
absent.
usually procumbent, sometimes erect, (not flexuous), unbranched or branched, (1–)1.5–3(–5) dm.
erect, ascending, or decumbent, branched or unbranched, (0.6–)1–5 dm, (slightly flexuous).
(soon withered), not rosulate.
(often withered by anthesis), not rosulate, 5–15-foliolate, (2.7–)4–14(–19) cm, leaflets petiolulate;
petiole 0.7–5 cm, (ciliate or not);
lateral leaflet blade oblong, ovate, or elliptic, smaller than terminal, margins entire, repand, crenate, or 3 (or 5)-lobed;
terminal leaflet (petiolule 0.3–1.7 cm), blade reniform, broadly ovate, or suborbicular, 0.5–2.5 cm × 4–30 mm, margins repand, crenate, or 3 or 5-lobed.
absent.
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).
3–15, 5–15-foliolate [leaves (2–)3.5–5.5(–7) cm, including petiole], petiolate, leaflets petiolulate;
petiole base not auriculate;
lateral leaflets similar to basal, (0.4–2.5 mm wide).
ebracteate.
ebracteate.
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.
sepals oblong, 1.5–2.5 × 0.7–1 mm, lateral pair not saccate basally;
petals white, spatulate, 2.5–4(–5) × 1–1.7 mm; (stamens rarely 4, lateral pair absent);
filaments 2–3 mm;
anthers ovate, 0.3–0.5 mm.
divaricate to ascending, (6–)10–15(–20) mm.
divaricate or ascending, (5–)6–14(–17) mm.
linear, (torulose), 1–1.5(–2) cm × 0.8–1.1 mm;
ovules 40–80 per ovary;
style 1.5–2.5 mm.
linear, (torulose), (0.8–)1.2–2.8 cm × 1–1.5 mm;
ovules 18–40 per ovary;
style 0.3–1(–1.5) mm.
brown, oblong to ovoid, 0.9–1.1 × 0.5–0.6 mm.
brown, oblong or subquadrate, 0.9–1.5 × 0.6–1 mm, (narrowly margined or not).
= 32.
Cardamine rotundifolia
Cardamine flexuosa
According to J. Lihová et al. (2006), the populations referred to Cardamine flexuosa in North America comprise two taxa of different polyploid origins and evolutionary histories: tetraploid C. flexuosa (2n = 32), native to Europe, and the octoploid taxon informally called “Asian C. flexuosa” (2n = 64), native to eastern Asia. For the latter, the name C. flexuosa subsp. debilis can be used. Nevertheless, these two taxa should be recognized at species level and the correct name for the Asian species should be sought. Based on available data, both taxa occupy the same habitats in North America, but the Asian taxon is much more widespread. The occurrence of European C. flexuosa was, until now, confirmed only for Washington, where both taxa have been recorded. More detailed studies of the North American distributions of both these weeds are needed.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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