Cirsium scariosum Nutt.
Elk thistle (Cirsium foliosum (Hook.) DC and C. drummondii Torrey & A. Gray misapplied)
Habit: 2 to 6 dm. high, perennial, arachnoid-villous stem, corollas pale or white.
Distribution: Montane coniferous, in meadows and moist places from British Columbia to Baja California and the Rocky Mountains.
Seed unit: Achene.
Seed: 3 to 5 mm. long, oblong-obovate, more or less compressed, pappus 15 to 30 mm.
Embryo: Foliar with well developed cotyledons, no endosperm.
Purity instructions: Pure seed definition:
AOSA: PSU# 50 - Intact achene, with or without one or more of the following structures: beak, bristle, hairs, pappus, wing, or firmly attached floral remnants, provided a true seed with some degree of embryo development can be detected (either by slight pressure or by examination over light).
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.
ISTA: PSD#1 – Achene with or without pappus, unless it is obvious that no seed is present.
Average pure seed units per gram: 1,764 seeds per gram (based on AOSA pure seed units only from 1 sample received for testing from 2002).
Range of percent pure seed: 4%
Range of percent inert: 96%
Description of inert: Plant material, broken seed.
Planting instructions: 400 seeds, TB, 21 days @ 20-30°C; for fresh and dormant seed, prechill recommended.
References: (link to main reference page)
Hickman, J.C., Ed. 1993. p. 239.
Munz, P.A. and D.D. Keck. 1968. p. 1277.
Ransom Seed Laboratory