The interaction between parasitic plants and their hosts is an important topic in both agriculture and ecology. Little, however, is known about that of the hemiparasite Pedicularis. It is essential to understand the host dependence and preference of Pedicularis for successful cultivation of plants in this genus and for understanding the roles they play in natural communities. We tested the effects of two herbaceous host species (Trifolium repens and Polypogon monspeliensis) on the survival and growth performance of Pedicularis cephalantha. Five P. cephalantha seedlings and two host plants were planted in each pot. In the control, no host plants were planted (treatment 1). Host plants were planted in three combinations: only T. repens (treatment 2) or P. monspeliensis (treatment 3) or a mixture of both (treatment 4). The results showed that P. cephalantha performed better in the presence of host plants, and host plants are more essential to P. cephalantha for proper development than for survival. The grass host P. monspeliensis proved to be a better host plant for P. cephalantha than the legume host T. repens. The high dependence of P. cephalantha on host plants and its host preference were demonstrated in this study. This is the first report of the performance of Chinese Pedicularis species in cultivation throughout all life stages (from seeds to seeds).

Self-pollination has been hypothesized to be beneficial in environments where pollinators are rare as it can provide reproductive assurance. This study presents evidence for an autonomous self-fertilization mechanism in the winter flowering plant, Brandisia hancei. To determine changes in the spatial separation of stigma and anthers, the length of style and stamens was recorded. Additionally, pollination treatments were carried out to test fruit-set and seed production. Brandisia hancei is herkogamic in the early flowering stages. However, different growth rates of the filament and style lead to contact of stigma and anthers in the later stages, thereby facilitating self-pollination. The highest seeds number is produced under an out-crossing scenario but plants produce a considerable number of seeds even when purely selfed. Although pollinators are scarce, autonomous selfing alleviates the pollen limitation in B. hancei. Self-fertilization in B. hancei seems to be an adaptive strategy to ensure reproduction when pollinators are scarce.

Brandisia hancei (Paulowniaceae) is a widely distributed shrub in karst regions in southwestern China. Its seeds have a membranous wing, and they mature just before the rainy season begins. To assess the effect of the wing on seed dispersal and germination of B. hancei , we measured the dispersal distance at varying wind speeds and release heights, falling duration from different release heights, floating duration on still water, rates of imbibition of water, and drying and soil adherence to seeds. Germination experiments were conducted on intact and de-winged seeds immediately after harvest. The wing increased the falling duration in still air and the floating ability on water. Dispersal distance of winged and de-winged seeds did not differ at a wind speed of 2.8 m s −1 , but at 3.6 and 4.0 m s −1 dispersal distances were greater for de-winged than for winged seeds. Seed wing had little effect of absorption and retention of water, but significantly increased soil adherence to the seeds. Mature seeds were non-dormant and germinated to over 90% with a mean germination time of about 10 days. By combining the environmental conditions in karst habitat with the seed traits of B. hancei , we conclude that dispersal and germination of winged seeds are adapted to the precipitation seasonality in heterogeneous habitats absence of soil.

No abstract

Didynamous stamens are separated into two pairs of different length, and the implication of this arrangement has not been well understood. The functional advantages of didynamous stamens were investigated in Brandisia hancei. Change of stamens during floral aging was recorded; the quantity, viability, and siring ability of pollen grains were tested; the anther arrangement was manipulated into four types based on stamen category and number, and fruit set and number of seeds per fruit were measured. Didynamous stamens exhibited staggered anther arrangement, and pollen sacs dehisced gradually. There was no difference for quantity, viability, and siring ability of pollen grains between the two pairs of anthers. Seed production after the removal of one long and one short stamen was higher than that of two long or two short stamens. Through prolonging pollen presentation and promoting delayed selfpollination, staggered arrangement and sequential dehiscence of anthers in didynamous stamens facilitate reproductive fitness of B. hancei.