WATER SHARING AMONG RAMETS IN A DESERT POPULATION OF DISTICHLIS-SPICATA (POACEAE)

Clonal growth enables plants to transport resources among separately rooted but connected ramets, a potential advantage in patchy or unpredictable habitats. Nevertheless, clonal plants are relatively scarce in deserts. To test whether clonal integration of water relations can increase plant performance under natural conditions in a desert species, water movement was traced and connection among ramets was manipulated in the rhizomatous grass Distichlis spicata in Death Valley, California. To examine potential costs of clonal growth form, connections were mapped and analyzed for dry mass and nitrogen content. Movement of dye showed potential transport of water among five ramets up to 1.4 m apart. Severance of connecting rhizomes increased mortality and decreased water potential of individual ramets within 36 hr, indicating that water sharing among ramets could be of significant benefit. However, plants had a high investment of mass and nitrogen in underground organs, which might be a cost of clonal growth associated with desert environments.