OregonFlora: Elatine californica vs. Elatine brachysperma

	Elatine californica	Elatine brachysperma
	California waterwort	short-seed waterwort
Habit	Plants 1.5–7 cm.	Plants 3–10 cm.
Stems	light green to green (reddish green); internodes 2–12 mm.	green; average internode length 6–15 mm.
Leaves	blades spatulate or elliptic, 3–12 mm; petioles 0.5–6 mm.	blades obovate or obovate-elliptic, 3–8 mm; petioles average length 0.5–1 mm.
Inflorescences	peduncles recurved, usually > 1.5 mm.	peduncles straight; ~0.1 mm.
Flowers	(0.1)1.5–4 mm; sepals 4, sometimes 1 smaller; petals 4; stamens 8; carpels 4.	sepals 3; petals 3; stamens 3; as long as petals or slightly shorter; carpels 2–4.
Fruits	disk-shaped to compressed globose, 4-locular.	globose or pressed globose, 2- to 4-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.	10–45, slightly curved to nearly straight, 0.4–0.5 mm; surface pits < 16 per row; length 0.5–nearly 1 × their width.

	Elatine californica	Elatine brachysperma
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.	Mudflats near lakes and reservoirs. Flowering Jun–Jul. 1200–1700 m. BR, Owy, ECas. CA, NV, WA; throughout much of western, southern, and central US, Mexico; Argentina. Native. Elatine brachysperma can be distinguished from other Elatine species growing in Oregon by the number of its seed surface pits, which is fewer than 16 per row. In Oregon, this species is critically imperiled, but it is secure in neighboring states (heritage rank: “G5, S1” [Oregon Biodiversity Information Center, 2016]), e.g., in California.
Source	Flora of Oregon, volume 2, page 613 Hamid Razifard, Gordon Tucker, Donald Les	Flora of Oregon, volume 2, page 613 Hamid Razifard, Gordon Tucker, Donald Les
Sibling taxa	E. brachysperma, E. chilensis, E. rubella	E. californica, E. chilensis, E. rubella
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: 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

Elatine brachysperma

California waterwort

short-seed waterwort

Habit

Plants 1.5–7 cm.

Plants 3–10 cm.

Stems

light green to green (reddish green);

internodes 2–12 mm.

green; average internode length 6–15 mm.

Leaves

blades spatulate or elliptic, 3–12 mm;

petioles 0.5–6 mm.

blades obovate or obovate-elliptic, 3–8 mm;

petioles average length 0.5–1 mm.

Inflorescences

peduncles recurved, usually > 1.5 mm.

peduncles straight; ~0.1 mm.

Flowers

(0.1)1.5–4 mm;

sepals 4, sometimes 1 smaller;

petals 4;

stamens 8;

carpels 4.

sepals 3;

petals 3;

stamens 3; as long as petals or slightly shorter;

carpels 2–4.

Fruits

disk-shaped to compressed globose, 4-locular.

globose or pressed globose, 2- to 4-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.

10–45, slightly curved to nearly straight, 0.4–0.5 mm;

surface pits < 16 per row; length 0.5–nearly 1 × their width.

Elatine brachysperma

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.

Mudflats near lakes and reservoirs. Flowering Jun–Jul. 1200–1700 m. BR, Owy, ECas. CA, NV, WA; throughout much of western, southern, and central US, Mexico; Argentina. Native.

Elatine brachysperma can be distinguished from other Elatine species growing in Oregon by the number of its seed surface pits, which is fewer than 16 per row. In Oregon, this species is critically imperiled, but it is secure in neighboring states (heritage rank: “G5, S1” [Oregon Biodiversity Information Center, 2016]), e.g., in California.

Source

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

Sibling taxa

E. brachysperma, E. chilensis, E. rubella

E. californica, E. chilensis, E. rubella

Web links