Hemizonia fasciculata (DC.) Torrey and A. Gray
Tarweed 

Family:  Asteraceae

Habit:  Annual, stems 1 to 10 dm. high.  Fall-flowering xerophyte, glandular and very aromatic.

Distribution:  Frequently found in coastal sage scrub, oak woodland, and grassland from California’s central coast to Baja California.

Seed unit:  Achene.

Seed:  Dimorphic:  Ray achenes 2 to 3 mm., beaked, three-angled, with no pappus.  Disk achenes 2.5 to 3 mm. with 5 to 12 pappus scales.

Embryo:  Foliar embryo, 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 #4 – Achene, with or without pappus, unless it is obvious that no seed is present.

Lab notes:  Samples are often heavily contaminated with other species.

Average pure seed units per gram:  2,295 seeds per gram (based on AOSA pure seed units only from 48 samples received for testing from 1993 to 2004).

Range of percent pure seed:   13 to 33%

Range of percent inert:  64 to 83%

Description of inert:  Plant material, broken seed, stone, dirt, sclerotia.

Planting instructions:  400 seeds, TB, 21 days @ 20°C; for fresh and dormant seed, prechill recommended.

References: (link to main reference page)
Hickman, J.C., Ed.  1993.  p.282.
Munz, P.A. and D.D. Keck.  1968.  p. 1120.
Ransom Seed Laboratory

 

Copyright © Ransom Seed Laboratory - All rights reserved