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The effect of water stress on the phenology of Namaqualand species was determined for five ephemeral species which were sown on four dates (April, May, June and July). Water stress shortened the life-span and flowering period of all five ephemeral species. Plants subjected to water stress were smaller and produced fewer flowers/inflorescences at peak flowering and fewer reproductive organs during their flowering period than control plants. Water stress had no significant effect on the number of leaves on the main stem at the time of flower/inflorescence initiation. There was, however, a tendency for water stress to delay the time to anthesis in April plants, while the flowering date was accelerated in June and July plants, increasing the probability of seed set before the end of the season. (C) 1996 Academic Press Limited