Biodiversity Science ›› 2009, Vol. 17 ›› Issue (5): 468-475.doi: 10.3724/SP.J.1003.2009.09036

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Breeding system and pollination biology of Crocus alatavicus (Iridaceae), a geocarpic subalpine plant of the western Tianshan Mountains

Yang Zhang, Dunyan Tan*   

  1. Xinjiang Key Laboratory of Grassland Resources and Ecology, College of Grassland and Environment Sciences, Xinji-ang Agricultural University, Urümqi 830052
  • Received:2009-02-12 Online:2009-09-20
  • Dunyan Tan

Crocus alatavicus, a geophytic-geocarpic plant, is an early spring ephemeral species that grows in subalpine areas of the western Tianshan Mountains. To understand the ecological significance of geocarpy in plants, we studied the breeding system and pollination biology of C. alatavicus, with special reference to its adaptive strategies for a subalpine existence. We found that C. alatavicus is hysteranthous and its flowering pattern was explosive at the population level. It began to flower in early- to mid-April, and the white flowers had neither nectar nor scent. The inferior ovary was below ground at anthesis, while the other floral parts were aboveground. The flowers were open during the day and closed at night, and individual flower duration was 6–9 days. Pollen viability was 75.39±5.69% at the end of anthesis, and stigma receptivity lasted eight days. Results of artificial pollination experiments suggested that the breeding system of C. alatavicus is facultative xenogamy with the ability to self-pollinate spontaneously. Crocus alatavicus has a generalist pollination system, with Bombus lucorum, Anthophora senilis and Andrena capillosa being effective pollinators. These insects initiated pollination while foraging for pollen, and their visitation frequencies were 0.50±0.27, 0.18±0.08 and 0.13±0.05 per flower per hour, respectively. Thus, C. alatavicus not only has evolved unique flowering pattern and generalist pollination system, but also utilizes an otherwise vacant niche in the early spring to improve the effectiveness of pollination. Furthermore, characteristics of its breeding system, such as self-compatibility and spontaneous self-pollination, ensure reproductive success even when pollinators are scarce and pollinator visitation frequencies are low in early spring.

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