Mass Allocation and Self-Burial of Aristida tuberculosa Florets

Abstract

COLLINS, B. S. AND G. R. WEIN (Savannah River Ecology Laboratory, Aiken, SC 29802). Mass allocation and self-burial of Aristida tuberculosa florets. J. Torrey Bot. Soc. 124:306-311. 1997.-Aristida tuberculosa is an annual grass of impoverished old fields on the southeastern coastal plain. Mature florets have hygroscopic awns and self-bury; florets that do not implant usually do not germinate, or seedlings fail to establish. We examined the influence of soil fertility on mass allocation in Aristida plants and florets, and the consequences of relative investment in caryopsis and awn for self-burial on litter and bare substrate. In the greenhouse, soil fertility did not influence mean per-floret mass or awn length, but fertilized plant florets had lighter caryopses and greater relative investment in awn than unfertilized plant florets. In field-collected propagules, caryopsis mass and awn length were inversely related to soil fertility; mean per-floret mass and relative investment in awn and caryopsis did not differ among fields. Relative investment in awn and caryopsis did not influence floret burial in field or greenhouse trials. Litter cover did enhance burial in both the field and the greenhouse; florets buried deeper in the heavier litter of the most fertile field site. We conclude that, although soil fertility influences floret biomass allocation in Aristida, relative allocation to awn and caryopsis does not influence floret performance.