OregonFlora: Elatine rubella vs. Elatine californica

	Elatine rubella	Elatine californica
	red-stem waterwort, southwestern waterwort	California waterwort
Habit	Plants 1.5–4 cm.	Plants 1.5–7 cm.
Stems	green to reddish green; internodes 1–7 mm.	light green to green (reddish green); internodes 2–12 mm.
Leaves	blades oblanceolate, 3–7 mm; petioles 0.5–1 mm.	blades spatulate or elliptic, 3–12 mm; petioles 0.5–6 mm.
Inflorescences	peduncles straight; < 1.5 mm.	peduncles recurved, usually > 1.5 mm.
Flowers	0.1–0.5 mm; sepals 3, sometimes 1 smaller; petals 3; stamens 3; carpels 3.	(0.1)1.5–4 mm; sepals 4, sometimes 1 smaller; petals 4; stamens 8; carpels 4.
Fruits	compressed globose to globose, 3-locular.	disk-shaped to compressed globose, 4-locular.
Seeds	15–30, slightly curved to nearly straight; ~0.5 mm; surface pits 14–23 per row; length ~2 × their width.	16–24, highly curved to nearly circular, 0.5–0.7 mm; surface pits 20–27 per row; length 1.2–2 × their width.

	Elatine rubella	Elatine californica
Distribution	[WildflowerSearch map] [BONAP county map]	[WildflowerSearch map] [BONAP county map]
Discussion	Emergent form in mudflats near reservoirs, submersed form in marshes. Flowering Apr–Jul. 1100–1600 m. BR, Owy. CA, ID, NV, WA; western North America. Native. Collections of Elatine rubella often are misidentified as E. chilensis, and vice versa, because of high similarity between the two species and the seed features not being readily visible. The emergent form of this species usually has more rigid stems and shorter internodes.	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.
Source	Flora of Oregon, volume 2, page 614 Hamid Razifard, Gordon Tucker, Donald Les	Flora of Oregon, volume 2, page 613 Hamid Razifard, Gordon Tucker, Donald Les
Sibling taxa	E. brachysperma, E. californica, E. chilensis	E. brachysperma, E. chilensis, E. rubella
Web links	Local floras: BC, CA, OR 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 californica

red-stem waterwort, southwestern waterwort

California waterwort

Habit

Plants 1.5–4 cm.

Plants 1.5–7 cm.

Stems

green to reddish green;

internodes 1–7 mm.

light green to green (reddish green);

internodes 2–12 mm.

Leaves

blades oblanceolate, 3–7 mm;

petioles 0.5–1 mm.

blades spatulate or elliptic, 3–12 mm;

petioles 0.5–6 mm.

Inflorescences

peduncles straight; < 1.5 mm.

peduncles recurved, usually > 1.5 mm.

Flowers

0.1–0.5 mm;

sepals 3, sometimes 1 smaller;

petals 3;

stamens 3;

carpels 3.

(0.1)1.5–4 mm;

sepals 4, sometimes 1 smaller;

petals 4;

stamens 8;

carpels 4.

Fruits

compressed globose to globose, 3-locular.

disk-shaped to compressed globose, 4-locular.

Seeds

15–30, slightly curved to nearly straight; ~0.5 mm;

surface pits 14–23 per row; length ~2 × their width.

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

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

Elatine californica

Distribution

[WildflowerSearch map]

[BONAP county map]

[WildflowerSearch map]

[BONAP county map]

Discussion

Emergent form in mudflats near reservoirs, submersed form in marshes. Flowering Apr–Jul. 1100–1600 m. BR, Owy. CA, ID, NV, WA; western North America. Native.

Collections of Elatine rubella often are misidentified as E. chilensis, and vice versa, because of high similarity between the two species and the seed features not being readily visible. The emergent form of this species usually has more rigid stems and shorter internodes.

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.

Source

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

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

Sibling taxa

E. brachysperma, E. californica, E. chilensis

E. brachysperma, E. chilensis, E. rubella

Web links