Seed-set by experimental crosses

To estimate the potential ability to produce seeds at each site (ridge, slope, and valley), we conducted artificial pollination experiments within and nearby the quadrats over 2 years (2010 and 2011). The total numbers of pin and thrum plants pollinated were 78 and 77 during 2010 and 59 and 81 during 2011, respectively. The plants were covered with fine-meshed nylon nets to exclude insect visitors. For each plant, one target flower bud was emasculated just before opening, and other flowers were removed. After opening of the target flowers, hand pollination was conducted by legitimate pollen grains collected from a single pollen donor growing at least 5 m away from the recipient plant. All fruits derived from the pollination treatments were harvested just before dehiscence, and the number of seeds and undeveloped seeds or ovules were counted using a microscope.