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short-seed waterwort

Asian waterwort

Habit Herbs, submersed or emersed on wet substrates, 0.5–3(–5) cm. Herbs, submersed, 1.5–4(–8) cm.
Stems

ascending or prostrate, branched.

prostrate or erect, branched.

Leaves

reddish green;

stipules lanceolate, 0.5–0.6 mm, margins dentate, apex acute;

petiole (0–)1–3 mm;

blade narrowly oblong to ovate, 3–8 × 1–3 mm, base cuneate to rounded, apex rounded to obtuse.

green;

stipules lanceolate, 1 mm, margins dentate, apex acute;

petiole 0.1–1 mm;

blade lanceolate or oblong-elliptic, 2–6 × 0.5–1.5 mm, base cuneate, apex obtuse to acute.

Pedicels

0–0.4 mm, erect.

0.5–2.5 mm, recurved in fruit.

Flowers

sepals (2–)3, equal, oblong-ovate, 1.1–1.3 × 0.3 mm;

petals 3, pinkish, elliptic or ovate, 1–1.5 × 0.5 mm;

stamens 3;

styles 3.

sepals 3, equal, oblong-ovate or broadly lanceolate, 0.5 × 0.3 mm;

petals 0 or 3, reddish, long-elliptic or ovate, 1–1.5 × 0.5 mm;

stamens 3;

styles 3.

Capsules

globose, 3-locular, 1.1–1.7 mm diam.

oblong-ovoid, 3-locular, 1 mm diam.

Seeds

(6–)10–15 per locule, oblong, straight or curved to 30°, 0.3–0.5 × 0.1–0.3 mm;

pits ± round, length 1–2 times width, in 6(–8) rows, (9–)14–17 per row.

10 per locule, narrowly oblong, straight or curved 15–30°, 0.3 × 0.1 mm;

pits obscure, round, length 1–4 times width, in 6 rows, 19–25(–30) per row.

Elatine brachysperma

Elatine ambigua

Phenology Flowering summer–early fall. Flowering late spring–summer.
Habitat Muddy shores, often of ponds or reservoirs. Pools, marshy places, rice fields.
Elevation 0–1500(–2200) m. (0–4900(–7200) ft.) 0–100 m. (0–300 ft.)
Distribution
from FNA
AL; AZ; CA; GA; IL; LA; MT; NE; NM; NV; OH; OK; OR; TX; WA; WY; BC; Mexico (Baja California); South America (Argentina)
[WildflowerSearch map]
[BONAP county map]
from FNA
CA; CT; MA; SC; VA; s Asia; se Asia [Introduced in North America; introduced also in Europe, s Pacific Islands, Australia]
[BONAP county map]
Discussion

Elatine ambigua is a popular aquarium plant usually misidentified as E. trianda. It is also a common weed in rice fields. This species probably was introduced to California, South Carolina, and Virginia through rice farming. Its introduction to Connecticut and Massachusetts probably was through aquarium disposal or fish stocking.

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

Source FNA vol. 12, p. 353. FNA vol. 12, p. 352.
Parent taxa Elatinaceae > Elatine Elatinaceae > Elatine
Sibling taxa
E. ambigua, E. americana, E. californica, E. chilensis, E. heterandra, E. minima, E. ojibwayensis, E. rubella, E. triandra
E. americana, E. brachysperma, E. californica, E. chilensis, E. heterandra, E. minima, E. ojibwayensis, E. rubella, E. triandra
Synonyms Alsinastrum brachyspermum, E. obovata, E. triandra var. brachysperma, E. triandra var. obovata, Potamopitys brachysperma
Name authority A. Gray: Proc. Amer. Acad. Arts 13: 361, 363. (1878) Wight: Bot. Misc. 2: 103, suppl. plate 5. (1830)
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