Abstract:

Weather patterns in desert environments (e.g., dry heat, strong winds, dust storms, and temperature fluctuations) can be highly unpredictable and can have deleterious effects on sexual reproduction of flowering plants. The herb Limonium otolepis is a dominant species in desert areas of Xinjiang, northwest China; however, reproductive strategies in unfavorable environments remain to be explored. Overall, we addressed flowering pattern and pollination modes, flowering process, floral traits, pollinators, and fruiting characteristics of L. otolepsis in Junggar Basin region. We employed scanning electron microscopy to examine the morphology of pistil stigmas and pollen grains. The flowering period of L. otolepis was from early June to mid-July, with extended flowering due to unsynchronized flowering phenology among individuals in the same population. During a given day, it showed a concentrated flowering and pollen release, with anthesis lasting for about 6-8 h. Petals unfolded at about 8:00 and reached the peak of flowering at about 9:00, with no more flowers opening after 11:00. One flower produced 752 pollen grains with a small amount of nectar. The pollen exine ornamentation was reticulate. Insects, including bees and hoverflies, were primary pollinators. Highest visiting frequencies occurred between 9:00 and 14:00. L. otolepsis was mainly outcrossing given that automatic selfing yielded a few seeds. Overall, fruit sets of open-pollinated flowers were 36.1%. Within inflorescences, fruit sets on basal flowers (45.7%) were significantly higher than those on neighboring flowers (3.3%). Mast flowering in L. otolepis reported here may facilitate pollination in unpredictable weather conditions. The reproductive strategy may also dispense reproductive risk by maintaining flowering asynchrony to prolong overall flowering period.

Key words: Limonium otolepis, floral display, pollination pattern, reproductive strategies, desert plant