Aspects of the biology of Ehrharta erecta Lam.

Abstract

Field and laboratory studies of the South African grass Ehrharta erecta Lam. are presented. Seasonal growth and the soil seed bank were monitored at Mornington, Victoria, where E. erecta is naturalized beneath native Leptospermum laevigatum F. Muell. scrub. Adult plant growth commenced in late autumn, following a severe reduction in green shoot material resulting from drought damage. Seedlings emerged in autumn and winter and coincided with a significant decline in the soil seed bank. Germination trials indicated dormancy in fresh seed, which could readily be broken by a period of after‐ripening. Germination was also found to be inhibited by the presence of seed covering structures, but this effect diminished with time. A growth experiment conducted at different light intensities demonstrated a high level of shade tolerance in E. erecta with the compensation point ranging from 0·82 to 0·98% of full daylight. In view of the speciese’ shade tolerance and other evidence, it is hypothesized that the availability of water restricts the ability of E. erecta to grow under very dense canopies and controls its seasonal growth and regeneration pattern in the field.