八角柱头和花粉的形态结构分析

Morphology and Structure Analysis of Stigma and Pollen of Illicium verum

应用体视显微镜和扫描电镜,观察红花、淡红花、白花、黄花4个花色品种八角的柱头和花粉形态结构。结果表明:柱头颜色因花瓣颜色而异,表现为红花、淡红花类的柱头,颜色有红色、白色,其中白花、黄花类的柱头颜色均为米白色。不同花色品种的八角花柱及柱头均呈"J"型卷曲,品种间无明显差异。柱头上有密集分布的圆棒状或圆球状乳突,乳突表面有分泌物、内部近于空虚,易扁瘪或破损。乳突表面纹饰因不同花色品种存在明显差异,白花类乳突表面呈近圆形或不规则条形凸起,分泌物较多,而红花、淡红花、黄花类乳突表面呈细网状皱纹,分泌物较少。各花色品种花粉的形状、萌发沟、外壁纹饰结构基本相同,形状以扁圆形、扁球形为主,具3条萌发沟,沟长至两极,外壁具纹饰网状,网眼呈不规则的多边形。花粉粒极轴长15.45~25.01μm,赤道轴长19.26~27.15μm,极赤比0.73~1.01,体积4 409.78~6 990.04μm3,花色品种间差异显著,其中淡红花、白花的花粉体积较大,说明花粉粒大小一定程度上受不同花色品种的影响。所研究的八角品种虽然花瓣颜色各异,但其柱头和花粉外表形态结构基本相似。

The morphology of stigma and pollen of 4 Illicium verum varieties with different flower colors （red, reddish, white and yellow） were observed by stereomicroscope and scanning electron microscope （SEM）. Results showed that color of stigma varied according to the color of petals. Red or white stigmata were associated with red or reddish petals, while creamy white stigmata were found with only white or yellow petals. No obvious difference was found in morphological characters of style and stigma among varieties. All style and stigma exhibited a curly shape ＂J＂. Papillae with either a roundbar or spherical shape and abundant sticky secretion were found densely distributed on the stigma. These papillae closed to empty inside and largely found flat or broken. Significant differences exist on surface ornamentation of papillae with different colors of flowers. The surface of white flowers′ papillae was subcircular or had irregular protrusion, contained more sticky mucus; in comparison, red, reddish, yellow flowers′ papillae had small webshake wrinkles on surface and contain less mucus. The pollen grains of all observed star anise varieties were similar on shape, germinal furrow, and extine ornamentation. The primary shapes of pollen grains were oblate and suboblate, tricolpate （3 germinal furrow） almost extending to the both poles. The extine of pollen grains were marked with faint irregular lines, resembling a network of minute cells thate have irregular polygon shapes. The polar axis（P） length was 1545-2501μm, equatorial axis （E） length was 1926-2715μm, P/E was 073-101, and the volume of pollen grain was 440978-699004μm3, and there were obvious difference between varieties. Reddish and white flowers had larger pollens than red and yellow flowers. The pollen grain size was affected to some extent by different color of varieties. Despite their different flower colors, the four star anise varieties shared similar surface morphology and structure of stigma and pollen.