Elatine

Linnaeus

Sp. Pl. 1: 367. 1753.

Common names: Waterwort élatine
Etymology: Greek name for a plant with firlike leaves
Synonyms: Crypta Nuttall
Treatment appears in FNA Volume 12. Treatment on page 349. Mentioned on page 348.
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Herbs, submersed or emergent aquatic, glabrous. Stems erect, ascending, decumbent, or prostrate, with longitudinal air spaces, rooting at nodes. Leaves: stipules membranous; petiole present or absent; blade margins entire, with hydathodes. Inflorescences: flowers usually solitary, sometimes 2[–3] per node. Pedicels present or absent. Flowers: 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 membranous. Seeds 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.

Distribution

North America, Mexico, South America, Europe, Asia, Africa, Pacific Islands, Australia.

Discussion

Species ca. 25 (10 in the flora).

Key

1 Petals 2; capsules 2-locular. Elatine 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. Elatine californica
3 Seeds straight or curved to 15º; pedicels 0.1–23 mm, erect; Quebec. Elatine 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. Elatine ambigua
4 Pedicels erect, 0–0.5 mm. > 5
5 Stamens 1–6, number variable within plant. Elatine heterandra
5 Stamens 3. > 6
6 Seed pits ± round, (9–)14–17 per row. Elatine brachysperma
6 Seed pits angular-hexagonal, (13–)16–35 per row. > 7
7 Seeds ellipsoid, pit length 3–5 times width; stipule margins entire. Elatine 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. Elatine 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. Elatine triandra
9 Leaf blades obovate or broadly spatulate, apices rounded to shallowly emarginate. Elatine americana
... more about "Elatine"
Hamid Razifard +, Gordon C. Tucker +  and Donald H. Les +
Linnaeus +
Waterwort +  and élatine +
North America +, Mexico +, South America +, Europe +, Asia +, Africa +, Pacific Islands +  and Australia. +
Greek name for a plant with firlike leaves +
duncan1964a +, fassett1939a +, fernald1917a +  and fernald1941a +
Crypta +
Elatine +
Elatinaceae +