Variation In Seed Characteristics And Growth For Thistles (Cardueae: Asteraceae) In California And Oregon

Abstract Genera in the tribe Cardueae (Asteraceae) include both non-invasive and invasive species widely dispersed in the western U.S. Seed characteristics are important for seed dispersal, seedling growth, and seedling survival. We determined seed characteristics and their variation from natural populations of 22 taxa of Cardueae. We also measured C and N content of seeds for 17 taxa, and conducted a greenhouse growth experiment with five species from this group. We tested the hypothesis that it is possible to distinguish invasive species from non-invasive species based on these characteristics. Seed weight differed significantly (P 0.05). Seed N, C, and C∶N ratio differed significantly (P < 0.0...