SIZE-DEPENDENT REPRODUCTIVE AND VEGETATIVE ALLOCATION IN ARUM-ITALICUM (ARACEAE)

The proportional allocation of plant total resources for growth, reproduction, vegetative propagation, and the balance between them were examined in Arum italicum. A minimum threshold dry mass (2.5 g) was found in this species before reproduction could occur, but above 10 g of dry mass, all individuals in a sample of 151 produced at least one inflorescence. Resource allocation for vegetative growth, sexual reproduction, and vegetative propagation significantly increased as dry mass of the plant increased. Increases in plant size resulted in increased proportional allocation to sexual reproduction, and relative decreases in both vegetative growth and vegetative propagation. Mass ratios between sexual reproductive structures and new tuber, and between sexual reproductive structures and organs of clonal growth increased with plant size. Allocation of resources to reproduction occurred at the expense of vegetative growth. In reproductive plants, the cost of reproduction, measured as relative reduction in vegetative growth was approximately 24% and was estimated by comparing growth in nonreproductive plants.