Biological characteristics of flowering and pollination of Iris sanguinea

A field investigation about the floral syndrome, the flowering dynamics, pollen activity and stigma receptivity,out-crossing index,pollen-ovule ratio,fruit set and seed-set and pollinators of Iris sanguinea was carried out. The I.sanguinea population in Harbin started to bloom in early June, and reached full bloom in the middle of June which lasted about one week. The blooming ended in late June. The flowering season of this population was about 20 days and the life span of a single flower was about 2 days. The extrorse anther was closed to the lateral side of the petaloid style. The distance between the anther and the stigma was about 1 mm and the relative position between them was constant during the whole blooming period. The out-crossing index (OCI) was 4 and the ratio between pollen and ovule (P/O) was 276.26 which indicated a breeding system of out-crossing,part self-compatibility,and insect pollinator-dependence. The highly specialized floral structure was adapted to the behavior of the pollinators,Apis mellifera etc. Artificial cross-pollination improved reproductive success,suggesting that sexual reproduction may be influenced by pollen limitation and less pollinators in nature.