Developmental Constraints: Effect on Population Growth and Patterns of Resource Allocation in a Clonal Plant

A comparison of ramet population growth rates in a flowering and a nonflowering population of Eichhornia crassipes Solms., the water hyacinth, indicates that inflorescence production is inversely correlated with ramet population growth rate. The differences in patterns of resource allocation exhibited by the two populations are explained in terms of developmental constraints acting on the differentiation and growth of a limited meristem population. The meristem population is limited in size by the developmental morphology of the ramets. This interpretation contrasts with more traditional ones in which fixed carbon, measured as dry weight, is viewed as the limiting currency. The inadequacy of fixed carbon as a limiting currency for plant resource allocation studies is discussed in relation to the origins of its use in the zoological literature. While most animals must acquire all usable carbon through a single mouth and then apportion it among competing needs, herbaceous plants generate new "mouths" (= carbon acquiring organs) as they build aboveground structure.