Pollen tube through wind, water or pollinators. The last step before fertilization is the growth of the pollen tube to transfer non-motile sperm to the protected egg. Pollen tubes are unique to plants and their structure had evolved over plant history. The pollen tube formation is complex and the mechanism is not fully understood, but is of great interest to scientists. Pollen is produced by the stamen, the male reproductive organ of the flower. Each pollen grain contains a vegetative cell, and a generative cell that divides to form two sperm cells. The pollen is delivered by the opening of anthers for
Minuartia groenlandica it does flower anywhere between June to August. In this period pollen grains are transported from flower to flower by insects. The most effective insect to transport pollen grains is the bumblebee "Bombus terricola". This is due to tiny hairs on the bee that collect pollen, and the bee's habit of crawling all over the flower in low temperatures when it is too cold to fly. Greenland stitchwort is found in areas of high elevation where bedrock is exposed. The plant grows on rocky ledges and in fine gravel on slopes. The soil in this area has a pH of