Chung, Kuo-Fang , Tsai, Yong-Hsin , Lin, Shu-Tzong , Liu, Hsiao-Lei .
Asynchronous dichogamy in Sassafras randaiense.
Sassafras randaiense (Lauraceae), an ecologically and economically important tree noted as the sole host plant of the highly endangered broad-tailed swallowtail butterfly (Agehana maraho), is a rare and vulnerable endemic species with scattered and isolated populations in the mid elevation forest of Taiwan. Although considerable efforts had been invested to conserve this precious species, silviculture of S. randaiense remains challenging due to its low and variable seed production, deep seed dormancy, and high mortality of seedlings. Recently Chung et al. (Ann. Missouri Bot. Gard. 97: 1-10. 2010) reported that S. randaiense is hermaphroditic and protogynous with a possible sexual system of synchronous dichogamy, rejecting previous accounts claiming polygamy for the species. To test this proposition that may partially explain its unpredictable seed yield, the reproductive biology of S. randaiense was investigated during its flowering seasons in 2009 and 2010. With the aid of three scaffold observatories in Chilanshan areas, the sexual phases of 165 inflorescence buds of four trees were recorded and tracked for their entire flowering periods. Photographs were also taken at a one hour interval for selected inflorescences to record the changes of sexual phase and flower visitors. Surprisingly, although our observations confirm the protogyny in S. randaiense, flowers within an individual tree did not change their sexual phase synchronously. Instead the bright and flesh white stigma, signifying the female phase of each flower, lasted for less than 4 days and then became brown and wilted, following by the male phase. For each tree, female phase flowers were present for 8 to 13 days, and at the 7th day, portion of male phase flowers exceeded those of female phase. Based on field observations and interval timing shooting, diptera were the most frequent visitors, with moths also being recorded by camera at night time. Our data clearly show that asynchronous dichogamy better characterizes the sexual system of S. randaiense and geitonogamy is possible with an individual tree.
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1 - National Taiwan University, School of Forestry and Resource Conservation, No. 1, Sec. 4, Roosevelt Road, Taipei, 10617, Taiwan
2 - National Ilan University, Department of Forestry and Natural Resources, No.1, Sec. 1, Shennong Rd., , Yilan City, Yilan County, 26047, Taiwan
plant reproductive ecology.
Presentation Type: Poster:Posters for Topics
Location: Hall A/Convention Center
Date: Monday, August 2nd, 2010
Time: 5:30 PM