SEED BIOLOGY OF 3 SPECIES OF MESEMBRYANTHEMA IN THE SOUTHERN SUCCULENT KAROO

The seed biology of three Mesembryanthema species, Brownanthus ciliatus (Ait.) Schwant., Rhinephyllum macradenium (L. Bol.) Schwant. and Drosanthemum montaguense L. Bol. was studied at the Tierberg Karoo Research Centre in the Prince Albert district of the southern Karoo. Variation in capsule and seed numbers was recorded over three sampling periods representing different seed production events. In addition, the soil seed bank was investigated, as well as capsule opening rates and seed germination behaviour. Generally, there was a decline in capsule and seed numbers with time, suggesting that the canopy-stored seed bank is limited to the current year's seed production. Large soil seed banks did not appear to be characteristic of the species studied. Our estimates of seed production were larger than estimates of other researchers, possibly due to time of data collection. Our findings are related to the community structure and dynamics of the vegetation on the study site.