疣花三角兰（Trias verrucosa）的生殖策略

首次报道了中国兰科新记录属三角兰属(Trias),并对该属及该属新种疣花三角兰(T.verrucosa Z.J.Liu,L.J.Chen et S.P.Lei)进行了描述与讨论。三角兰属含19种,分布于自印度的阿萨姆经缅甸向东南扩展至印度尼西亚与澳大利亚,向西南延伸至印度德干高原。它在云南西部的发现进一步表明了该地区与热带亚洲在植物地理学上的亲密关系。新种生于林下较阴蔽的石上,对其物候学与开花生物学特征的观察,发现该物种有大量世代重叠的克隆分株,未见结实的植株,克隆繁殖的发生与分株是否开花无关。花期自4月初至5月初,花在植株或花序上的开放毫无规律,而且单花的花期较短,仅有4～5d,未发现有结实的花。交配系统检测,人工自花传粉和异花传粉的花未见有结实。由于该植物的花期常处于雨季来临之前,此时干燥,风力大,低温和弱光的生态条件对于植物的开花、传粉、结实显然是不利的。缩短开花时间和不结实可避免植株的能量在不利环境的无效消耗,将有限的能量用于其较为有效的无性繁殖,增加了在不可预测环境中繁衍的机会,以保障繁殖的成功。它的P/O(花粉/胚珠)值为187.4±22.4,显然是与它的花粉粘合成坚硬块状可在传粉中的高效利用有关,表明该物种仍然保留有性繁殖的特性。该种植物所采取强化无性繁殖,弱化有性繁殖生殖策略是对该地区较为恶劣生态条件的适应,可能正是由于这个原因,疣花三角兰能够在远离其同属近亲的地方生存下来。

The reproduction strategy of Trias verrucosa from China

Trias, an orchid genus, is reported from China as a newly recorded genus for the first time. The genus and its new species, T. verrucosa Z. J. Liu, L. J. Chen et S. P. Lei, are described and discussed. Trias consists of 19 species ranging from Assam of India via Myanmar to Indonesia and Australia in the southeast and to Decan of India in the southwest. Its occurrence in West Yunnan of China is a further indication of phytogeographical relations between this region and tropical Asia. This new species grows on shady rocks in forests. By observations of its biological characteristics such as phenology and blooming biology, lots of cloned ramets of generation overlap were found, but there were no fruited plants, clonal reproduction could repeat with no relations to whether the ramet blooms or not. The flowering season of this species is from early April to early May. The opening of flowers on plant or inflorescence was irregular and the florescence of single flower was rather short, only lasting 4-5d, and no fruited flowers were found. Based on the detection of mating system, no flowers of artificial self-pollination and artificial cross-pollination have fruited. Since the flowering period is just before the rainy season of this region, the ecological conditions of dryness, strong wind, low temperature and weak light during that time are evidently unfavorable to plant blooming, pollinating and fruiting. Apparently the short duration and sterility of each flower would avoid the invalid energy waste in unfavorable circumstance and save the limited energy for more valid asexual reproduction, so that the opportunity of multiplication in uncertain environment would be increased to ensure the progenitive success. The P/O value of T. verrucosa is 187.4±22.4 which is obviously related with the high valid usage of its conglutinated and hard tuberous pollinarium during pollination, indicating that this species could hold the characteristic of sexual reproduction. This is an adaptation of this plant to the rather atrocious ecological circumstance there by its reproduction strategy of strengthening asexual reproduction and weakening sexual reproduction and probably for this it enabled the plants to survive in this region, long-distanced from the places where its relatives dwell.