Mating system of the endangered Haloxylon ammodendron (Amaranthaceae) in the Gurbantunggut desert (China)

In the arid region of northwest China, H. ammodendron has become the main pioneer species for the restoration of plant communities. However, the breeding system of the plant remains unknown. The floral dynamics and the breeding system characteristics of H. ammodendron were investigated in this study, using a bagging experiment. The results show that anthesis lasted about 22 d. The longevity of individual flowers was 14.1 d. Stigma receptivity lasted about 6 d and there were relatively long periods for the meeting between stamen and stigma. Anther height was slightly greater than that of the stigma. The outcrossing index was 2 and the pollen-ovule ratio was 64,815. The H. ammodendron mating system can be described as a mixed mating system with facultative apomixis; pollination is not necessary for reproduction. The mixed mating system with facultative apomixis could guarantee the reproductive success of H. ammodendron in severe desert conditions with sparse pollinators.

Elementary apomictic processes in Rubus L.

Two elementary apomictic processe were found in the examined <em>Rubus</em> species: <em>R. saxatilis</em> developed diplosporous and aposporous embryo sacs, <em>R. caesius</em> - displosporous, apart from meiotic ones. These result; confirmed the wide occurrence of facultative apomixis and intraspecific differentiation of the mode of reproduction within the taxa of the investigated genus.