Morphology and Structure Analysis of Stigma and Pollen of Illicium verum

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 15.45-25.01 μm, equatorial axis (E) length was 19.26-27.15 μm, P/E was 0.73-1.01, and the volume of pollen grain was 4 409.78-6 990.04 μm³, 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.