Department of Botany, Miami University, Oxford, Ohio 45056 USA.
Am J Bot. 2002 Sep;89(9):1373-87. doi: 10.3732/ajb.89.9.1373.
The breeding system and the embryology of Consolea spinosissima, a tree-like opuntioid endemic to Jamaica, were investigated. Morphological and embryological studies revealed that the species is subdioecious, with three sexual morphs present in the 150 × 120 m plot studied at Hellshire Hills, Jamaica. The female morph has pistillate flowers with open stigma lobes, no pollen grains, and sets fruit. The male morph has cryptic staminate flowers with closed stigma lobes, viable pollen grains, and a nonfunctional gynoecium that does not set seed. The weak hermaphrodite morph has low fruit set and "perfect" flowers that superficially resemble the functionally staminate flowers of the male morph. These perfect flowers reach anthesis with viable pollen grains, with no or only a few functional ovules, and with the style supporting pollen tube growth. Embryological studies showed that the critical stage for sex determination occurs earlier in pistillate than in staminate and perfect flowers. Anthers of pistillate flowers abort prior to microspore tetrad formation, whereas ovules of the staminate and perfect flowers degenerate after the complete maturation of the embryo sac. Based on flower structure and embryological data, we hypothesize that the ancestor of C. spinosissima is/was hermaphroditic.
对牙买加特有树状仙人掌属 Consolea spinosissima 的繁殖系统和胚胎学进行了研究。形态学和胚胎学研究表明，该物种是雌雄异株的，在牙买加赫尔斯希尔山研究的 150×120m 样地中存在三种性形态。雌性形态具有柱头裂片张开的雌花，没有花粉粒，结出果实。雄性形态具有隐蔽的雄花，柱头裂片闭合，有活力的花粉粒，以及没有功能的雌蕊，不能结籽。弱两性花形态的结实率较低，其“完全”花在外观上类似于雄性形态的功能雄花。这些完全花在有活力的花粉粒存在下开花，很少或没有功能的胚珠，花柱支持花粉管生长。胚胎学研究表明，在雌雄同体花中，性别决定的关键阶段比雄花和完全花更早发生。雌花的花药在小孢子四分体形成之前就退化了，而雄花和完全花的胚珠在胚囊完全成熟后退化。基于花结构和胚胎学数据，我们假设 C. spinosissima 的祖先为两性花。
