Pollen cell. In flowering plants the vegetative tube cell produces the pollen tube, and the generative cell divides to form the two sperm cells. Pollen is produced in the microsporangia in the male cone of a conifer or other gymnosperm or in the anthers of an angiosperm flower. Pollen grains come in a wide variety of shapes, sizes, and surface markings characteristic of the species (see electron micrograph, right). Pollen grains of pines, firs, and spruces are winged. The smallest pollen grain, that of the forget-me-not ("Myosotis" spp.), is around 6 µm (0.006 mm) in diameter. Wind-borne pollen grains can be
Thalassia testudinum flowers open. There are two methods of pollination: hydrophily and biotic pollination. Through hydrophily, the pollen grains are carried through the water column by tides or currents and deposited upon an open pistillateflower. More recent investigation however, has uncovered active biotic pollination.Underwater video cameras have revealed that Crustacean, Polychaete, and Amphipoda swam towards open male flowers. These creatures were attracted to the seagrass’s nutritious mucilage—a carbohydrate-rich substance that houses pollen. As the invertebrates feeds on the mucilage, excess pollen grains stick to their bodies. They move from flower to flower feeding and spreading the pollen from male to female. Seeds