OregonFlora: Elatine californica vs. Elatine chilensis

	Elatine californica	Elatine chilensis
	California waterwort	Chilean waterwort
Habit	Plants 1.5–7 cm.	Plants 0.5–4 cm.
Stems	light green to green (reddish green); internodes 2–12 mm.	green to reddish green; internodes 2–7 mm.
Leaves	blades spatulate or elliptic, 3–12 mm; petioles 0.5–6 mm.	blades oblong to oblanceolate, 2–6 mm; petioles 0.4–1.2 mm.
Inflorescences	peduncles recurved, usually > 1.5 mm.	peduncles straight; < 1.5 mm.
Flowers	(0.1)1.5–4 mm; sepals 4, sometimes 1 smaller; petals 4; stamens 8; carpels 4.	0.1–0.5 mm; sepals 3, sometimes 1 smaller; petals 3; stamens 3; carpels 3.
Fruits	disk-shaped to compressed globose, 4-locular.	compressed globose to globose, 3-locular.
Seeds	16–24, highly curved to nearly circular, 0.5–0.7 mm; surface pits 20–27 per row; length 1.2–2 × their width.	18–36, slightly curved to nearly straight; ~0.5 mm; surface pits 16–25 per row; length 3–5 × their width.

	Elatine californica	Elatine chilensis
Distribution	[WildflowerSearch map] [BONAP county map]	[WildflowerSearch map] [BONAP county map]
Discussion	In or near puddles, ponds, reservoirs, lakes, and marshes. Flowering Mar–Aug. 50–1600 m. Col, ECas. CA, ID, NV, WA; northeast to MT, southeast to NM, south to Mexico. Native. Elatine californica can be distinguished from all other Elatine species in the Unites States by its four-merous flower parts and nearly circular seeds. Both morphological and molecular analyses (Razifard et al. 2017) support a close affinity between E. californica and E. hydropiper, which occurs in Central Asia, Europe, and North Africa.	Emergent form on mudflats near lakes and reservoirs, submersed form in shallow lake waters. Flowering Apr–Sep. 0–2600 m. BR, ECas, Lava, WV. CA, NV, WA; western North America; South America. Native. Elatine chilensis has an amphitropical disjunction in its distribution between southern South America and western North America. The exact cause of disjunction remains unclear, although birds might be responsible for dispersing the minute seeds of this species between the two regions (Carlquist 1983).
Source	Flora of Oregon, volume 2, page 613 Hamid Razifard, Gordon Tucker, Donald Les	Flora of Oregon, volume 2, page 614 Hamid Razifard, Gordon Tucker, Donald Les
Sibling taxa	E. brachysperma, E. chilensis, E. rubella	E. brachysperma, E. californica, E. rubella
Synonyms		Elatine americana, Elatine triandra
Web links	Local floras: CA, OR, WA Local Web sites: CalFlora, CalPhotos, Flora NW, PNW Herbaria WildflowerSearch iNaturalist (observations) USDA Plants Database LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search	Local floras: CA, OR, WA Local Web sites: CalFlora, CalPhotos, Flora NW, PNW Herbaria WildflowerSearch iNaturalist (observations) USDA Plants Database LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search

Elatine chilensis

California waterwort

Chilean waterwort

Habit

Plants 1.5–7 cm.

Plants 0.5–4 cm.

Stems

light green to green (reddish green);

internodes 2–12 mm.

green to reddish green;

internodes 2–7 mm.

Leaves

blades spatulate or elliptic, 3–12 mm;

petioles 0.5–6 mm.

blades oblong to oblanceolate, 2–6 mm;

petioles 0.4–1.2 mm.

Inflorescences

peduncles recurved, usually > 1.5 mm.

peduncles straight; < 1.5 mm.

Flowers

(0.1)1.5–4 mm;

sepals 4, sometimes 1 smaller;

petals 4;

stamens 8;

carpels 4.

0.1–0.5 mm;

sepals 3, sometimes 1 smaller;

petals 3;

stamens 3;

carpels 3.

Fruits

disk-shaped to compressed globose, 4-locular.

compressed globose to globose, 3-locular.

Seeds

16–24, highly curved to nearly circular, 0.5–0.7 mm;

surface pits 20–27 per row; length 1.2–2 × their width.

18–36, slightly curved to nearly straight; ~0.5 mm;

surface pits 16–25 per row; length 3–5 × their width.

Elatine chilensis

Distribution

[WildflowerSearch map]

[BONAP county map]

[WildflowerSearch map]

[BONAP county map]

Discussion

In or near puddles, ponds, reservoirs, lakes, and marshes. Flowering Mar–Aug. 50–1600 m. Col, ECas. CA, ID, NV, WA; northeast to MT, southeast to NM, south to Mexico. Native.

Elatine californica can be distinguished from all other Elatine species in the Unites States by its four-merous flower parts and nearly circular seeds. Both morphological and molecular analyses (Razifard et al. 2017) support a close affinity between E. californica and E. hydropiper, which occurs in Central Asia, Europe, and North Africa.

Emergent form on mudflats near lakes and reservoirs, submersed form in shallow lake waters. Flowering Apr–Sep. 0–2600 m. BR, ECas, Lava, WV. CA, NV, WA; western North America; South America. Native.

Elatine chilensis has an amphitropical disjunction in its distribution between southern South America and western North America. The exact cause of disjunction remains unclear, although birds might be responsible for dispersing the minute seeds of this species between the two regions (Carlquist 1983).

Source

Flora of Oregon, volume 2, page 613
Hamid Razifard, Gordon Tucker, Donald Les

Flora of Oregon, volume 2, page 614
Hamid Razifard, Gordon Tucker, Donald Les

Sibling taxa

E. brachysperma, E. chilensis, E. rubella

E. brachysperma, E. californica, E. rubella

Synonyms

Elatine americana, Elatine triandra

Web links