Floral phenology and compatibility of sawgrass, Cladium jamaicense (Cyperaceae)

Abstract

Sawgrass, Cladium jamaicense, is the dominant macrophyte in the Florida Everglades. We examined sawgrass flowering phenology and compatibility reactions in ex situ and in situ populations over 2 yr. Sawgrass flowers in May in southern Florida. Flower maturation was relatively synchronous within an inflorescence. Along the entire inflorescence, functionally male flowers emerged initially, followed by stigmas, then anthers of hermaphroditic flowers. Flowers of each sex expanded over 2 d with less than 1 d in between, totaling 6- 7 d for an inflorescence to complete flowering. Hand pollinations showed that sawgrass was self-compatible and not pollen-limited, because open pollinations produced fruit set similar to self- and cross-pollinations. Fruit set was low in autogamy and manipulation treatments. Manipulation treatments were used to study the effect of exposure to airborne pollen during hand pollinations. This treatment thus provides a useful technique for studies on the in situ compatibility of wind-pollinated graminoids. Sawgrass was able to self-fertilize, but the timing of flower maturation on an inflorescence promoted outcrossing. Actual outcrossing rates in sawgrass thus depend on clonal architecture and the timing of floral maturation on other inflorescences within a clone rather than on inflorescences of other genets in a population.

Trends and missing parts in the study of movement ecology

“…In an evolutionary sense, however, plants can affect the direction and distance of dispersed seeds, and even their specific deposition site (18,19). For example, some wind-dispersed species release seeds during turbulent winds (14,20,21), when they are more likely to ride updrafts and reach distant sites (14). Some terrestrial plant seeds also have adaptations to facilitate movement along the ground and settlement in crevices (14).…”

Implications of discontinuous elevation gradients on fragmentation and restoration in patterned wetlands

“…Our analysis for the southern section suggests fragmentation via a loss of cohesion of sawgrass ridges and consolidation of sloughs, but not a total disappearance of sawgrass. The sympodial growth form of sawgrass allows it to persist in less than ideal conditions for an extended period (Snyder and Richards 2005) by growing up, forming tussocks-or fragmenting at a local scale-instead of growing in continuous strands. This appears to be the pattern reflected in the southern portion of WCA3AS.…”

Seed Dispersal and Reproduction Patterns Among Everglades Plants

“…Daehler and Strong (1994) suggested that inbreeding depression was a possible factor contributing to the large variability of reproductive output in a study of clones of Spartina alterniflora. Snyder and Richards (2005) also noted that sawgrass can self-fertilize, although the sexes within an inflorescence are usually temporally separated. Ivey and Richards (2001) have found a rather uniform genetic structure in sawgrass throughout the Everglades water conservation areas.…”

“…Both crossing and selfing may occur in sawgrass populations in response to such factors as clone size, number of ramets, and timing of flowering (Snyder and Richards 2005). Variations in seed mass for selfed and out-crossed seeds of sawgrass are unknown for sawgrass, but seed mass of selfed seed is known to be smaller in some native species (Pinto-Torres and Koptur 2009).…”

“…Ripe fruits are primarily released during August (Snyder and Richards 2005). By August, the rain and winds of seasonal storms-coupled with high water levels-provide an optimal environment for hydrochorous sawgrass fruit dispersal (personal observation).…”