Versatile Modes of Propagation in Cladium jamaicense in the Florida Everglades

The Florida Everglades is a subtropical wetland dominated by Cladium jamaicense (sawgrass), a native sedge that forms extensive, monospecific stands. Sawgrass exhibits several modes of reproduction, including sexual (seed production) and asexual (rhizome propagation) types. In this study, the occurrence of vegetative proliferation on the reproductive organs of sawgrass, a phenomenon otherwise known in arctic-alpine habitats, was observed. This is the first time that vegetative proliferation has been reported in Cladium. Vegetative plantlets developed in the spikelets of the inflorescence but also commonly at the lower nodes on the inflorescence. The number of plantlets per inflorescence ranged from 400 to 4000. The plantlets differed in size from a few leaves to eight to ten leaves of up to 70 mm in length. Although the nutrient concentration of the seeds were greater than those of the plantlets, the total content of P, N and C of the plantlets was twice that of the seeds owing to the greater weight of the plantlets. In spikes with vegetative proliferation, the leafy shoot developed beside the ovary, and seed formation did not occur. Usually, only one plantlet developed in each flower, although more buds did form occasionally within a single flower. The simultaneous occurrence of diverse modes of propagation in sawgrass populations may be an adaptation to typical Everglades habitats with extreme interannual wet-dry cycles.