Phenology and branching in eight selected species of the genus Cliffortia
Master Thesis
1999
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University of Cape Town
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Abstract
To date the peculiarities of the inflorescence structure in the wind-pollinated genus Cliffortia (Rosaceae), has gone unnoticed. In this study stereo microscope examination and sketching of fresh and dried specimens, combined with extensive field observations, were performed on eight species of the genus. In its simplest form the inflorescence is a reduced short shoot, bearing a lateral e-bracteate flower and a potentially viable apical bud. Variations in the basic structure can be in the number of flowers, the mix of the sexes of the flowers and the number and type of short shoots as primary, secondary and tertiary axes. A high incidence of structural plasticity of the inflorescence exists. Structural changes can take place throughout the development of the inflorescence or only at the onset of the vegetative stage. These changes occur in the short shoot(s) constituting the axes of the inflorescence, causing either an increase in the length of the internodes, apical proliferation of the axes or a combination of these two effects. A specific combination of changes is linked to a specific inflorescence type. The vegetative elements of the inflorescence thus modified, are retained as an integral part of the vegetative branching system, instead of being discarded after the shedding of the fruits. Thus the inflorescence disappears without being discarded, while the integration of the inflorescence matrix into the vegetative elements of the plant, has a marked effect on the vegetative branching pattern. In some species the structural changes in the inflorescence are linked to changes in the predominance of one sex over the other over time, so that an individual, initially of the one sex, can become one of the opposite sex by the end of the season. In the past the erroneous interpretation of a single point in the process of a sex change as if it is a permanent state of sexuality, led to the prevalent acceptance of dioecy as the norm for the genus, while in truth, it is monoecy with dichogamy in this genus, as in many other wind-pollinated taxa.
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Fellingham, A. 1999. Phenology and branching in eight selected species of the genus Cliffortia. University of Cape Town.