Habit: Perennial, with rhizomes, stems
5 to 10 dm., purplish at base becoming straw-colored above.
Distribution: Found in marshes, pond margins, vernal pools, and
ditches. Widespread in montane, temperate regions in
and throughout the Western Hemisphere.
Seed unit: Achene.
Seed: Achene triangular, strongly flattened, yellowish-brown, 1.5 to 2.5
mm.; tubercle (cap) is more or less conic. Perianth bristles
Embryo: Linear basal embryo.
AOSA: PSU #29 – Intact achene, with or without perianth,
whether or not a seed is present. Piece of broken achene larger
than one-half of the original size, unless no seed is present.
Seed, with or without pericarp/seed coat; if broken, larger than
one-half the original size.
Samples often have a high percentage of dormant seed; viability
of ungerminated seeds may be determined using TZ.
Average pure seed units per gram:
2,373 seeds per gram (based on AOSA pure seed units only from
17 samples received for testing from 1995 to 2004).
Range of percent pure seed:
79 to 99%
Range of percent inert: 1 to 13%
Description of inert: Plant material, broken seed, dirt.
Planting instructions: 400 seeds, TB, 21 days @ 20-35°C; prechill not
to main reference page)
Hickman, J.C., Ed. 1993. p. 1142.
Martin, A.C. and W.D. Barkley. 1961. p. 136.
Ransom Seed Laboratory