利用腊叶标本初探豹子花属植物的性表达及其与个体大小的关系

Male Flowers and Relationship between Plant Size and Sex Expression in Herbaria of Nomocharis Species(Liliaceae)

植物性系统进化过程中很少有植物通过雌性败育的方式实现性系统由联合走向分离,然而雄花在百合科植物中大量存在,引起了研究者的关注。本研究利用百合科豹子花属植物的腊叶标本,获取它们的花性别表型、花大小、株高以及分布海拔等信息探讨豹子花属植物的性表达样式,并对样本量较多的开瓣豹子花、云南豹子花、多斑豹子花和豹子花四个种的性表达及其与个体大小的关系进行分析。研究结果表明:1)六种豹子花属植物标本中都有雄花存在;根据雄性花和两性花的不同组合,形成雄性个体、两性花个体,和雄花两性花同株个体三种植株类型;2)个体大小(株高)和分布海拔之间不存在相关关系,和植株性别类型相关,即雄性个体一般显著小于具有雌性功能的两性花个体和雄花两性花同株个体;3)个体大小与花大小、每个个体开花总数和雌花数量成显著的正相关关系,而与每个个体的雄花数量无显著的相关关系。本研究更正了一直以来对豹子花属植物性系统的错误认识,首次报道雄花在豹子花属植物中普遍存在,并指出雄花和雄性个体的出现是大小依赖性分配的结果。同时,以研究实例证明了利用腊叶标本开展植物性系统多样性的可行性。

Despite the general rarity of female-sterile reproductive systems, male flowers are widespread in Liliaceae. Nomocharis （Liliaceae） consists of ca. seven species which have been traditionally classified as hermaphrodite. How- ever, our preliminary investigation suggested that male flowers may occur frequently in this genus. We got data of the flower sex phenotypes, flower size, plant height and altitude by observing and measuring specimens of Nomocharis from several herbaria （PE, KUN, HITBC CDBI） in China, and then used them to determine the sex distribution and to analyze the relationships between plant size and flower size, sex expression. We found that male flowers occurred in all six studied Nomocharis species and different combinations of hermaphroditic and male flowers at plant level resulted in complex sex expression. Of four further studied species, male plants were significantly smaller thanplants with hermaphroditic flowers in three species. Plant height, which was not related to altitude, but not sex phe- notype has significant effects on flower size. The number of total flowers and hermaphroditic flowers per plant increased with plant size. However, the number of male flowers was independently of size. Our study suggested resources availability （i. e. plant size） determined the sex phenotypes of individuals. We highlighted the occurrence of male flowers in genus Nomocharis and suggested further field studies are absolutely necessary. Furthermore, this study provides a case study to better use herbarium specimens as prerequisites for field researches of floral sexual diversity.