Abstract
Information on flowering seasons in the tropical rain forest is meagre and rather indefinite, although there appears in Nigeria to be a maximum flowering season at the beginning of the wet season and perhaps another at the end (Richards 1952). Much of the available knowledge concerns the striking gregarious flowering of many tropical species, and the effects of a weather-stimulus on buds which have developed to a certain size and then remained dormant, are well known. Observations on a number of flowering plants in the tropics have indicated a relationship between rainfall and flowering. The gregarious flowering of species of Coffea occurs a fixed number of days after rain, seven for C. arabica (Mes 1957) and three for C. rupestris (Rees 1964), whilst the flowering of two Zephyranthes and two Pancratium species was found by Holdsworth (1961) in Ghana to be related to rainfall respectively 4, 5, 3 and 3 days earlier. In Nigeria the liane Prevostea heudelotii (Convolvulaceae) also flowers gregariously in March and April, 5-8 days after rain. Coster (1926) described the flowering behaviour of Dendrobium crumenatum and other Malayan epiphytic orchids which follows 8-11 days, depending upon species, after a thunder-shower following a dry spell. Experimental work indicated that the effect of the showers is not directly that of rain but is due to the sudden temperature fall. In Bromheadiafinlaysoniana flowering occurs in mass 7 days after a markedly cool day (Holttum 1949). In Southern Nigeria, Clerodendrum incisum Baker, which is frequently grown as an ornamental shrub, produces, at somewhat irregular intervals throughout the year, large numbers of flowers, massed together in terminal clusters. Anthesis occurs over 2 or 3 days and the flowers are short-lived, the attractive long white corolla tubes becoming detached and forming a white carpet on the ground.
Published Version
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