Flora of North America species comparison

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Elatine brachysperma

Elatine

short-seed waterwort

mud-purslane, waterwort, élatine
Habit Herbs, submersed or emersed on wet substrates, 0.5–3(–5) cm. Herbs, submersed or emergent aquatic, glabrous.
Stems

ascending or prostrate, branched.

erect, ascending, decumbent, or prostrate, with longitudinal air spaces, rooting at nodes.
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.

stipules membranous;

petiole present or absent;

blade margins entire, with hydathodes.
Inflorescences

flowers usually solitary, sometimes 2[–3] per node.
Pedicels

0–0.4 mm, erect.

present or absent.
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 2–4, connate basally, equal or 1 smaller, not carinate, apex obtuse;

petals (0 or) 2–4, apex obtuse;

stamens [0–]1–8;

pistil 2–4-carpellate, ovary 2–4-locular, apex truncate;

styles 2–4;

stigmas 2–4.
Capsules

globose, 3-locular, 1.1–1.7 mm diam.

membranous.
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.

2–33[–44] per locule, brown to yellowish brown, straight or curved (nearly circular in E. californica), surface with hexagonal, rectangular, elliptic, or ± round pits (pits oriented with longer dimension at right angles to length of seed).
x

= 9.

Elatine brachysperma

Elatine
Phenology Flowering summer–early fall.
Habitat Muddy shores, often of ponds or reservoirs.
Elevation 0–1500(–2200) m. (0–4900(–7200) 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 USDA
North America; Mexico; South America; Europe; Asia; Africa; Pacific Islands; Australia
[BONAP county map]
Discussion

Species ca. 25 (10 in the flora).

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Key
1. Petals 2; capsules 2-locular.
E. minima
1. Petals usually 3–4, sometimes 0; capsules 3–4-locular.
→ 2
2. Sepals 4; petals 4; capsules 4-locular.
→ 3
3. Seeds curved 90–180°; pedicels 1.5–2.5(–3.5) mm, recurved in fruit; w United States.
E. californica
3. Seeds straight or curved to 15º; pedicels 0.1–23 mm, erect; Quebec.
E. ojibwayensis
2. Sepals 2–3 (rarely 4 in E. triandra); petals 3 (sometimes 0 in E. ambigua); capsules 3-locular.
→ 4
4. Pedicels recurved in fruit, 0.5–2.5 mm.
E. ambigua
4. Pedicels erect, 0–0.5 mm.
→ 5
5. Stamens 1–6, number variable within plant.
E. heterandra
5. Stamens 3.
→ 6
6. Seed pits ± round, (9–)14–17 per row.
E. brachysperma
6. Seed pits angular-hexagonal, (13–)16–35 per row.
→ 7
7. Seeds ellipsoid, pit length 3–5 times width; stipule margins entire.
E. chilensis
7. Seeds oblong or slenderly cylindric, pit length 1–3 times width; stipule margins dentate.
→ 8
8. Leaves reddish green; seed pit length 1–2 times width.
E. rubella
8. Leaves light green to green; seed pit length 2–3 times width.
→ 9
9. Leaf blades linear, lanceolate or narrowly oblong, apices acute or obtuse.
E. triandra
9. Leaf blades obovate or broadly spatulate, apices rounded to shallowly emarginate.
E. americana
Source FNA vol. 12, p. 353. FNA vol. 12, p. 349. Authors: Hamid Razifard, Gordon C. Tucker, Donald H. Les.
Parent taxa Elatinaceae > Elatine Elatinaceae
Sibling taxa
E. ambigua, E. americana, E. californica, E. chilensis, E. heterandra, E. minima, E. ojibwayensis, E. rubella, E. triandra
Subordinate taxa
E. ambigua, 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 Crypta
Name authority A. Gray: Proc. Amer. Acad. Arts 13: 361, 363. (1878) Linnaeus: Sp. Pl. 1: 367. (1753): Gen. Pl. ed. 5, 172. (1754)
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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