长角凤仙花（凤仙花科）的花器官发生和发育

以不同发育时期的长角凤仙花Impatiens longicornuta Y.L.Chen（凤仙花科Balsaminaceae）为材料，利用扫描电镜技术观察了其花器官的分化及其发育过程。长角凤仙花为两侧对称花，具2枚侧生萼片，唇瓣囊状，旗瓣具鸡冠状突起，雄蕊5枚，子房上位，5心皮5室。其花器官分化顺序为向心式，萼片—花瓣—雄蕊—雌蕊原基。2枚侧生萼片先发生，然后近轴萼片（即唇瓣）原基和2枚前外侧萼片原基近同时发生；但是这3枚萼片原基的发育不同步，远轴的2枚前外侧萼片原基的发育渐渐滞后，然后停止发育，最后渐渐为周围组织所吸收，直至消失不见。花瓣原基中，旗瓣原基最先发生，4个侧生花瓣原基相继成对发生，且之后在基部成对愈合形成翼瓣；5枚雄蕊原基几乎同时发生，5个心皮原基轮状同时发生。本文结果支持凤仙花属植物为5基数的花，并进一步证实了唇瓣的萼片来源；此外，研究结果表明花器官早期发育资料对植物系统与进化研究具有重要参考价值。

Floral Organogenesis and Development of Impatiens longicornuta(Balsaminaceae)

In the present study, the floral morphology and development patterns of Impatiens longicornuta Y. L. Chen (Balsaminaceae) has been examined under the scanning electron microscope (SEM) for a better understanding of floral evolution in the genus. I.longicornuta is zygomorphic flower; lateral sepals 2; lower sepal deeply saccate, abruptly constricted into an incurved spur, mouth oblique, tip acuminate; upper petal cucullate, crista apically with a long cornu; stamens 5; ovary superior; gynoecium 5-carpellate, syncarpous. Initiation of five sepal primordial is not consistent in order. The order of initiation is from two lateral sepals to adaxial primordium and two anterolateral sepals. Their development is not synchronous also. The two anterolateral sepals stay rudimentary and disappear in later stages. The anterior petal arises firstly, and then the four lateral petal primordia are initiated in two successive pairs and fused at the base in later stages. Five stamen primordia initiate nearly at the same time. Five carpel primordia arise simultaneously in whorl. The perianth of Impatiens is pentamerous and the standard is not petal but sepal actually. The floral organogenesis data of I.longicornuta shows the important systematic and evolutional significance.