薹草属少花薹草组(莎草科)的果囊形态及其系统学意义

Utricle morphology of the species in Carex sect. Paniceae(Cyperaceae) and its systematic significance

用扫描电镜观察了少花薹草组Carex sect. Paniceae (莎草科) 26种3变种的果囊形态和微形态特征。结果表明:(1)果囊形状(喙除外)为倒卵球形、椭球形或卵球形,均为钝三棱状,果囊长度为1.99~7.27 mm,喙多弯曲(仅1种C. striatula果囊的喙直立),喙急缩或渐缩,喙长与果囊长度的比值为1/8~1/2,表皮细胞多明显隆起,极少数隆起不明显,且多数性状种内保持稳定;(2)喙口形态分斜截、平截、微二齿和二齿4类,且在种内有变异,如C. arakiana、线柄薹草C. filipes、丝柄薹草C. rouyana、C. purpurifera;(3)可根据果囊长度和喙的收缩情况区分部分近缘种,如线柄薹草与少囊薹草C. egena、浙江薹草C. zhejiangensis与显舌薹草C. macroglossa;(4)果囊长度、喙长与果囊长度的比值在sect. Paniceae s.s.与sect. Laxiflorae 2组间有显著差异,对两组的界定有一定价值;(5)被视为组或亚属重要分类性状的果囊横切形状(三棱状或双凸状)在界定少囊薹草组与相关组时无意义,果囊形态对界定少花薹草组有重要的系统学意义。

The utricle morphological and micromorphological characters of 26 species and 3 varieties of Carex sect.Paniceae were investigated under scanning electron microscopy(SEM). The results reveal that(1) the shapes of utricle bodies(beak excluded) are obovoid, ellipsoid or ovoid, obtusely trigonous, the lengths of utricle ranged from 1.99 to7.27 mm, and beaks are almost bent(only C. striatula erect), abruptly or gradually contracted. The ratios of beak lengths and utricle bodies range from 1/8 to 1/2, and the epidermal cells are generally distinctly elevated, the cases that indistinctly elevated are rare. These characters remain stable within species;(2) beak orifices are obliquely truncated,truncated, 2-minute-lobed or bidentate, which are variable within species, e.g. in C. arakiana, C. filipes, C. rouyana,C. purpurifera;(3) the characters of utricle length and beak apical contraction can be used to distinguish the close species, such as C. filipes and C. egena, C. zhejiangensis and C. macroglossa;(4) the characters of utricle length and the ratio of utricle length to beak are valuable for distinguishing sect. Paniceae s. s. and sect. Laxiflorae;(5) the utricle cross-sectional shape(trigonous or biconvex) may be not work for defining the related sections of sect. Paniceae,although it is always considered as an important trait in subgeneric classification. The present study shows that the utricle morphology is of systematic significance in sect. Paniceae.