FLORAL MORPHOLOGY AND REPRODUCTIVE BIOLOGY OF FOUR SPECIES OF CYANELLA (TECOPHILAEACEAE)

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Summary

In the South African Cyanella alba, C. lutea, C. hyacinthoides and C. orchidiformis the androe-cium consists of an upper group of five or three stamens and one or three low stamens. Anthers of the upper and lower stamens differ in size and shape, and lower anthers produce much more pollen than upper ones. Pollen is released only when the poricidal anthers are forcibly beaten. The configuration of the androecium suggests that ‘feeding’ and ‘pollinating’ stamens are present; the manner of pollen discharge suggests vibratile pollination by heavy-bodied bees. According to the direction in which the style is deflected, C. alba and C. lutea have right-handed and left-handed flowers. In these two species, the lower stamen is deflected in a direction opposite to that of the style. Artificial pollinations were carried out with plants sampled from various field populations of the four species. The seed set data obtained indicate the presence of physiological self-incompatibility. No significant differences have been found in fertility of pollen from lower and upper anthers. In C. alba and C. lutea, the floral dimorphism together with a low number of flowers open at any time may be effective in promoting outbreeding. The ratio of pollen grains per flower to the number of seeds produced is much smaller in C. alba and C. lutea than in the other two species. It is possible that smaller numbers of pollen grains are required here, because the floral dimorphism enhances pollinations between flowers of different types.

Ancillary