Carbon translocation between parents and ramets of a desert perennial

Agave deserti, a semelparous, Crassulacean acid metabolism perennial occurring in the northwestern Sonoran Desert, propagates primarily vegetatively by ramets produced on rhizomes that extend less than 10 cm from the base of a parent plant. Carbon translocation from parents to ramets, measured after exposing leaves to ¹⁴CO₂, was essentially complete in 7 d, with parents exporting 3·3% of their assimilated carbon to ramets. Shading ramets below light compensation for 6 weeks more than doubled the amount of carbon exported from the parent to shaded ramets, compared with unshaded ramets. The total amount of carbon imported by a ramet from its parent was independent of the mass of the ramet. Although the net movement of carbon is expected to be towards the ramets, parents also received carbon from labelled ramets, indicating bidirectional translocation. The physiological integration of parents and ramets allows ramets to draw upon the reserves of the parent for up to 14 years, a longer period than for most other reported clonal species, thereby facilitating ramet growth and establishment in a resource-limited environment.