MORPHOLOGY, FLOWERING AND SEED PRODUCTION OF ZOSTERA-CAPRICORNI ASCHERS IN SUBTROPICAL AUSTRALIA

The vegetative morphology, flowering characteristics, seed production, and seed distribution in the sediment of the seagrass Zostera caprico rni Aschers. were studied for 18 months by monthly sampling. Three sea grass zones were studied. In each of these zones there was a different morphological type of Z. capricorni: small, dense plants in the midsh ore zone; large, sparse plants in the offshore zone; medium size and m edium density plants in the inshore zone. The distribution of seeds in the sediment was also studied in bare areas adjacent to these vegetat ed zones. Flowering lasted for 8 months, from September to April, with the highest percentage of shoots flowering in September and November. Flowering lasted longest in the midshore zone (7 months), compared wi th the inshore (3 months) and offshore (4 months) zones. The density o f flowering shoots was also higher in the midshore zone (341+/-14.0 fl owering shoots m(-2)) than in the inshore (4+/-1.0) or offshore (12+/- 4.0) zones. Both the mean number of spathes per shoot (3.1+/-0.07), an d the number of female flowers per spathe (4.8+/-0.20) did not vary si gnificantly between zones. However, there were more male flowers per s pathe in the offshore (10.5+/-1.55) than in the inshore (5.6+/-1.60) o r midshore (5.4+/-0.88) zones. Although most seeds were found in the m idshore zone during the flowering season (177m(-2)+/-28.4), some seeds remained in the Sediment for 4 months after seed production had cease d. Few seeds were found outside the seagrass beds, of these most were in bare areas long-shore of the seagrass.