Reproductive phenology in three Genisteae (Fabaceae) shrub species of the W Mediterranean Region

Nordic Journal of Botany (Impact Factor: 0.6). 06/1999; 19(3):345 - 354. DOI: 10.1111/j.1756-1051.1999.tb01126.x

ABSTRACT We studied the flower duration, the phenology of flowering and fruiting, and flower, fruit, and seed production in three Genisteae shrub species of the W Mediterranean Region: Cytisus multiflorus, C. striatus, and Retama sphaerocarpa. Flower duration was negatively correlated with temperature, and in the case of C. striatus it was also influenced by pollination. In Cytisus multiflorus, which flowers during winter in the population studied, two floral morphs were recognized differentiated by flower size, phenological pattern, and production of the reproductive organs: morph LF (large flowers) and morph SF (small flowers). The former is earlier in phenology but its reproductive success is less than the second since it not only produces significantly fewer flowers/plant, but also a smaller crop of fruit and seeds. The flowering of the LF morph lasted some three months and of the SF morph 11 weeks. The winter-spring flowering C. striatus, with a four month duration of flowering time, is sympatric with C. multiflorus and their flowering periods overlap, but the former is more successful reproductively. Retama sphaerocarpa is clearly spring flowering, with an extremely short duration of flowering (c. 6.5 weeks), but, unlike the other two species which disperse their seeds in the same season in which they are produced, it staggers the dispersal of its diaspores over more than one year. Despite the great flower per plant production, especially in Retama sphaerocarpa, and of the number of fruit initiated, the final crop of fruit and seed/plant is low in the three species (C. multiflorus: fruit 8.40% and seeds 1.96%; C. striatus: fruit 13.09% and seeds 4.12%; Retama sphaerocarpa: fruit 5.65% and seeds 1.33%).

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