Pollen morphology of the Sapotaceae from Thailand and its taxonomic implications

The external pollen morphology of the family Sapotaceae in Thailand was examined using the acetolysis method to determine its taxonomic significance. Pollen of 39 specimens belonging to 32 species was investigated by means of light and scanning electron microscopy. Pollen grains are found to be monads, isopolar, colporate, lalongate, and variable in size, shape, aperture number, colpus length and exine thickness. Exine ornamentation is also variable, showing more than one pattern on a single pollen grain. Principal component analysis based on 13 pollen characters identified three pollen groups: Chrysophyllum, Madhuca and Pouteria types based on pollen shape, size, the ratio of colpus length to the polar axis and exine sculpturing. Pollen morphology is taxonomically useful in the classification of the Thai Sapotaceae, especially in the taxonomic status of Planchonella and Pouteria species.