POLLINATION CHARACTERISTICS OF EPHEMEROID PLANT EREMURUS ANISOPTERUS

Abstract

Background and Aims This study was conducted to examine the pollination characteristics of Eremurus anisopterus, an ephemeroid plant in Gurbantunggut Desert in Xinjiang, China. Methords An integratve approach combining investigation in field with analysis in lab was adopted. Pollen traps were used to measure air_borne pollen loads, and artificial isolation experiments were applied to test the potentiality of cross_pollination or apomixes. Key Results Duration of flowering of Eremurus anisopterus varied from late April to middle May. Anthesis of a single flower often lasted for 1 d. However, if the daily maximum air temperature was under 20 ℃, the anthesis of a single flower could be prolonged to 2 d. Pollen_dispersion period of single flower could last for 4 to 5 h from 10∶30 to 15∶00 local time with the duration of pollen dispersion for single anther approximately 40 min. The heterotypical maturation of stamina could significantly prolonged the pollen_dispersion period of a single flower, suggesting an adaptation to the habitat of E. anisopterus in the desert where the pollinators were not reliable. The timing of blossom of the ephemeroid plant showed close correlations with wind velocity, habit and characteristics of the pollinators in the desert. Pollens of the plant might spread over 70 m by wind with approximately 60% of the pollens fallen within 20 m away from the plant. Insects, especially bee, hover fly, flesh fly, mason bee and Halictus sp. were very important pollination medium. Visitors, such as bee and hover fly, usually landed at the yellowish green spot on the tepal, and then entered the flower along the purple vein on the pink tepals. The yellowish green spot might be a mimetic structure to nectar that could attract insects to visit, which was also the result of the long_period adaptation of the plant to its sandy desert habitat. Higher visiting frequency was reached between 10∶30 and 13∶30. The P/O of E. anisopterus (6 164) suggested the species was of cross_pollination characteristic according to Cruden's criterion. However, artificial isolation experiment showed that E. anisopterus was self_compatible, which might act as a compensation mechanism for the inadequate outbreeding chances in the desert habitat. The fact that there was no seed set in bagged emasculated flowers indicated that there was no apomixes occur. Conclusions This study suggests that E. anisopterus might adapt the not_reliable pollinator habitat by self_compatible and lengthening pollen_dispersion period of single flower.