Abstract:

Aims Gentiana lawrencei var. farreri (Gentianaceae), a late-autumn or early-winter flowering alpine perennial, is distributed mainly in the northeastern Qinghai-Tibetan Plateau (QTP). The environment of the QTP is harsh because temperature is low and insects are scarce. Our aim is to examine the pollination ecology of G. lawrencei and its adaptive relationship with the environment.
Methods The pollination ecology of G. lawrencei was documented for three consecutive years in northeastern QTP. The breeding system was tested and floral visitors were observed during the flower life span. Flower longevity was recorded and stigma receptivity was tested by the seed-set ratio of different days in which the stigma was presented.
Important findings The seed-set of G. lawrencei under natural conditions was extremely low because of pollen-limitation. Combined characters of herkogamy and incomplete dichogamy indicate that pollinators are needed for complete pollination. Some individuals of G. lawrencei could produce seeds under bagging without emasculation, and it may be from selfing caused by thrips and ants. Bombus kashmirensisand B. sushikini are effective pollinators of G. lawrencei, but the frequencies of visits are extremely low (0.006 and 0.005 time·flower^-1·h^-1, respectively). Floral longevity and stigma receptivity are relatively long compared with other Gentianaceae species, and these increase the probability of pollination chances under low temperature and low pollinator conditions. The combination of self- and cross-pollination, as well as the prolonged floral longevity and stigma receptivity, may be the main reason for the survivorship of G. lawrencei.

Key words: Gentiana lawrencei var. farreri, late-flowering plants, pollination ecology, prolonged floral longevity, reproductive strategies