Floral Biology, Pollination, Pistil Receptivity, and Pollen Tube Growth of Teak (Tectona grandisLinn f.)

Teak flowers are weakly protandrous and pollen is shed within a few hours of flower opening. Pollen is tricolpate and 29 μm in diameter. The papillate stigma is of the wet type and is receptive from 1100–1300h. The style is hollow throughout its length. Nectar and pollen are the major floral rewards for pollinators. The major pollinators are Ceratina sp. which carry teak pollen on most parts of their bodies, especially the specialized hair structures (scopal brushes) on the tibia. The most effective pollination period in terms of flowers pollinated and pollen per flower is between 0900 and 1300h. At 1300h the number of pollen per flower is the highest, ranging from 1–36 (average 7). Pollen tubes grow very fast. Within 2 h after pollination 8% of the pollen tubes have reached the micropylar end of the ovule and pollen tubes first enter the embryo sac at 8 h. Only one to two pollen tubes enter the micropyles of a flower. Although 78% of flowers were pollinated in open-pollination, the low fruit set (3.5%) suggests that there are factors other than pollination limiting fruit set. The main factor appears to be a high amount of selfing, and self-incompatibility occurs when pollen tubes are arrested at the lower portion of the ovary.