|Xu, Suxia -|
|Huang, Qingyun -|
|Shu, Qingyan -|
|Chen, Chun -|
Submitted to: Scientia Horticulturae
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 6, 2008
Publication Date: January 1, 2009
Citation: Xu, S., Huang, Q., Shu, Q., Chen, C., Vick, B.A. 2009. Reproductive Organography of Bougainvillea spectabilis Willd. Scientia Horticultureae. 120:399-405. Interpretive Summary: Bougainvillea spectabilis Willd. is a popular ornamental shrub of prime importance for horticulture, as well as potentially for pharmaceutical industries, agriculture and environmental industries. However, its floral development is not yet well understood. The aim of this study was to characterize the developmental patterns of the floral organs of Bougainvillea at the anatomical level to better understand its unusual reproductive biology and to reveal factors underlying its poor sexual reproduction. Our results suggested that self-incompatibility, poor pollen viability, or ovule viability are the possible factors causing sterility of the species.
Technical Abstract: Bougainvillea spectabilis Willd. is of prime importance for horticulture, as well as potentially for pharmaceutical industries, agriculture and environmental industries. However, its floral development is not yet well understood. A detailed study on floral structure and floral organography in the species was first completed using microscopy of paraffin microtome sections of buds. The results were indicated as follows: First, the three trumped flowers in the cymose inflorescence develop asynchronously. Secondly, varieties with multi-whorl bracts do not develop any sexual organs, i.e., perianth, pistil and stamens. Thirdly, the wall of the two-loculus anther consists of two kinds of cells: the inner wall, consisting of thick-cytoplasmed cells and the outer wall, consisting of fibrous cells. Fourthly, the pollen grains, with three germination colpi, vary substantially in form and size in summer under the highest day temperature of 40 C. Fifthly, the pistil is characterized by a betalain-accumulating stylar brush. Following the developmental course, only one basal ovule is developed in the superior ovary. Finally, organs of one flower develop consecutively from the outer to the inner, i.e., from bracts, to calyx, stamen, and carpel while the three flowers bloomed one by one in one cymose inflorescence. It almost takes 1 week from first bud to the third flower blooming. Our research showed a series of special characteristics of reproduction organography of B. spectabilis which can be useful for understanding its reproduction biology and its sterility.