中国水韭属植物的孢子形态特征

Spore morphology of Isoёtes (Isoёtaceae) from China

利用扫描电镜观察了中国现存5种水韭属Iso?tes植物孢子的表面纹饰,并统计分析了孢子的大小(n=30)。结果显示:高寒水韭I.hypsophila大孢子表面光滑无突起纹饰,平均极面直径358μm,小孢子具脑回状纹饰,平均长度22μm;云贵水韭I.yunguiensis大孢子表面具脊条-网络状纹饰,纹饰突起较低,近极面较稀疏且不连成完全的网络,平均极面直径390μm,小孢子具疣状小颗粒至近于光滑的表面纹饰,平均长度22μm;台湾水韭I.taiwanensis大孢子表面具瘤状突起,平均极面直径312μm,小孢子表面具刺棘状突起,平均长度24μm;中华水韭I.sinensis大孢子表面具脊条状突起,平均极面直径409μm,小孢子表面具刺棘状突起,平均长度28μm;东方水韭I.orientalis大孢子表面具脊条-网络状纹饰,纹饰突起较高,近极面的网络较完整,平均极面直径420μm,小孢子表面具矮刺状-瘤状突起,平均长度34μm。比较类群间的孢子形态特征与染色体数目表明:5个类群的孢子表面纹饰区别明显,同时,孢子的大小可反映类群的倍性,孢子较小的高寒水韭、云贵水韭和台湾水韭是二倍体(2n=22),孢子较大的中华水韭(2n=44)和东方水韭(2n=66)为多倍体。孢子的形态特征在中国水韭属植物物种的鉴定与分类中具有重要意义。

Micromorphological characters of mega- and microspores of five Isoětes species from China were observed under scanning electron microscope （SEM）. Megaspores of I. hypsophila have a levigate ornamentation, and are 358 μm in diameter （mean, n=30）, microspores of this species have a gyrus ornamentation, and are 22 μm in length （mean, n=30）; megaspores of I. yunguiensis have a cristate-reticulate ornamentation, with a size of 390 μm in diameter （mean, n=30）, while microspores nearly smooth with some fine granulates, and with a size of 22 μm in length （mean, n=30）; megaspores of I. taiwanensis are tuberculate and 312 μm in diameter （mean, n=30）, echinate microspores are 24 μm in length （mean, n=30）; cristate megaspores of I. sinensis are 409 μm in diameter （mean, n=30）, and echinate microspores are 28 μm in length （mean, n=30）; megaspores of I. orientalis have a cristate-reticulate ornamentation, with diameter of 420 μm （mean, n=30）, microspores of this species have an echinate-tuberculate ornamentation with a size of 34 μm in length （mean, n=30）. Based on the morphological characters of spores and chromosome numbers among taxa, it was found that mean spore size in each species of Isoětes generally reflected the ploidy level. I. hypsophila, I. yunguiensis and I. taiwanensis, with smaller mean spore size, are diploidy with 2n=22; L sinensis （2n=44） and I. orientalis （2n=66）, with larger mean spore size, are polyploidy. The spore morphology of Isoětes still plays an important role in identification and classification of Isoětes from China.