Achene Biomass and Within-Achene Allocation Patterns of Five Co-occurring Goldenrod Species (Solidago: Compositae)

-Achenes of five goldenrod species (Solidago canadensis, S. graminifolia, S. juncea, S. nemoralis and S. speciosa) were collected from two old-field sites in southern Michigan to compare seed biomass and resource allocation within the fruit. The taxa differed from one another on the basis of total achene biomass as well as absolute biomass of embryo and fruit coat. The two species at the mesic sites within the old fields produced the smallest achenes, in terms of embryo and fruit coat biomass. The largest achenes were those of S. speciosa; adults of this species occur at sites with intermediate soil moisture. On average, embryos of these five species of goldenrod constituted 59% of the total biomass of the achene. There was no clear pattern of resource allocation within the achene with respect to habitat. Within each wet or dry site, however, species differed from one another in allocation to embryo (52% vs. 59%). Solidago speciosa had 65% of achene biomass as embryo, was least variable for fruit characters and differed from the other goldenrods in achene allometry. The absolute dry-weight investment in components of the achene more closely paralleled the distribution of adults along the soil moisture transect than did the allocation patterns.