Pollination Ecology, Breeding System, and Conservation of Caldesia grandis (Alismataceae), an Endangered Marsh Plant in China

瀕危植物寬葉澤苔草(Caldesia grandis, Samuelsson)的繁育系統、傅粉生態學和保護生物學研究

Wahiti Robert Gituru ； 王青鋒(Qing-Feng Wang) ； 王勇(Yong Wang) ； 郭友好(You-Hao Guo)

《Botanical Bulletin of Academia Sinica》 43卷3期 (2002/07) Pp. 231-240

https://doi.org/10.7016/BBAS.200207.0231

摘要

中國是世界上生物多樣性最豐富的地區之一，擁有世界上近1/8的維管植物物種。本文通過野外調查和實驗，封瀕危植物寬葉澤苔草在中國大陸目前僅存的三個自然居群的傅粉生態學和繁育系統進行了研究，並進行了生存力分析。寬葉澤苔草的花期爲七月上旬至九月下旬，八月爲其高峰期。單花的開放始於上午10點鍾，持續約四小時15分鍾。該種自交親和，但自花授粉的結實率輿自由傅粉相似，低於同株和異株異花授粉的結實率，在同一地點進行的開放式傅粉控制試驗顯示花粉活力和結實率均較高，分別焉65.44％和71.78％。寬葉澤苔草主要通過發生在花序上的珠芽進行繁殖。花期最頻繁的訪花者爲蠅頰，但有效傅粉的主體則爲蜂類。生存力分析顯示寬葉澤苔草死亡率的高峰出現在五月中旬，這輿此時的環境篩還有關，在此之俊倖存的幼苗開始定居。對該物種的威脅主要來自於災難性事件，尤其是人類活動的幹擾（如農業生崖、植物愛好者的採集和基礎設施建設等）。本文認爲建立有效的監網絡以及就地和遷地保護是保護寬葉澤苔草和其他瀕危水生植物的有效途徑。

關鍵字

澤瀉科 ； 寬葉澤苔草 ； 瀕危 ； 傅粉

並列摘要

Caldesia grandis Samuelsson is an endangered wetland herb on the brink of extinction in the vast area of Mainland China, which holds close to one eighth of the world’s vascular plant species. The pollination ecology and breeding system of C. grandis were investigated from three natural populations occurring in two wetlands near the top of Mangshan Mountain in Hunan Province, central China. The species is in flower from early July to late September with a peak in August. The process of flower anthesis in C. grandis begins at about 10.00 am and lasts about four-and-one-quarter h. The flowers lasted ca. 5.5 h. Caldesia grandis is self-compatible; however, autogamy resulted in lower seed set than geitonogamy and xenogamy as well as free pollination. Both pollen viability and the seed set in open-pollinated controls at the same site were typically high (65.44% and 71.78% respectively). Mean pollen: ovule ratios in the three populations ranged from 901.75 to 931.354. No seed germination was observed, either in the field or in laboratory experiments. Propagation is achieved through turions, which commonly occur in the inflorescences. Flies (Insecta; Diptera) were the most frequent visitors to the flowers of C. grandis; however, bees (Insecta; Hymenoptera) composed a larger proportion of effective pollinators. Existence analysis revealed a peak of mortality density in mid-May corresponding to an environmental sieve in the period following the establishment of plantlets. An updated diagnostic of the conservation status of C. grandis in China was formulated. The main threats to this species are catastrophic events, especially human impact activities (agriculture, hobbyists' collections, and infrastructure construction). Establishment of a monitoring program is proposed, and both in-situ and ex-situ strategies are recommended for effective conservation of C. grandis.

並列關鍵字

Alismataceae ； Breeding system ； Caldesia grandis ； Conservation ； Endangered ； Pollination ； Rare endemic