Characterizing plant attributes with particular emphasis on seeds in Tamaulipan thornscrub in semi-arid Mexico

Seed mass, dispersal syndromes and other plant attributes were investigated for 111 species native to north-eastern Mexico. We investigated whether seeds from Mexico conformed to patterns of seed size and dispersal syndrome spectra found for floras in arid environments from around the world. The distribution of seed mass in the Mexican flora (0.03-598 mg) was generally similar to that found elsewhere. All of the major seed dispersal syndromes previously found in arid environments were represented in Mexico, although vertebrate dispersal (33 species) was unusually common. There were 31 species having wind-dispersed seeds, four ant-dispersed and 43 with no obvious dispersal morphology. Woody species were more likely to have large seeds and herbaceous species were more likely to have small seeds. Woody plants had proportionally more wind-dispersed and less animal-dispersed species than did herbaceous plants. We did not find the expected relationship between time of seed set of vertebrate-dispersed species and the presence of migratory birds or between time of seed set and optimum germination time.