PHYSIOLOGICAL INTEGRATION FOR CARBON IN MAYAPPLE (PODOPHYLLUM-PELTATUM), A CLONAL PERENNIAL HERB

The degree of physiological integration among compartments within modular plants and animals, as measured by the sharing of resources, can determine the response of such organisms to environmental variability. We used C-14 tracer methods to determine distribution patterns for photoassimilate in mayapple, Podophyllum peltatum L., a rhizomatous perennial herb with a simplified clonal architecture. Over half of the carbohydrate fixed during mid May, 1988, ended up in older segments of the rhizome system by early autumn, 1988. Roots, rhizomes and nodes along the entire length of the rhizome system all contained labelled material. By the following spring, 1989, there was a proportionate increase in label in the newly developing segment. increases in activity in new roots and shoot between autumn and spring were accompanied by steep declines in activity in nearby rhizomes. Autoradiograms showed support of damaged rhizome branches by carbohydrate from attached, undamaged branches and the presence of carbohydrate fixed in 1988 throughout all structures of the developing 1989 shoot. No differences were seen in this study in the allocation patterns of systems with sexual or vegetative shoots. Mayapples exhibit high levels of physiological integration for carbohydrate compared to other, similar clonal perennials. This translocation may serve several functions, including storage and remobilization to support new growth, maintenance of an extensive root system and maintenance of a bud bank.