Pollen Morphology and Taxonomy

Pollen morphology and taxonomyShape and structure of pollen are crucial taxonomic features to determine similarities and dissimilarities of plant species. Pollen morphological studies aim to establish evolutionary relationships between plants at various organizational levels, ranging from populations over species to genera and families.
The taxonomy of the Anacardiaceae family is a matter of studies for more than 100 years and still in controversial discussion. The common classification orders the Anacardiaceae Lindl. family into five tribes: the Anacardieae, Semecarpeae, Spondideae, Rhoeae, and Dobineae with 80 genera and over 700 species. They are widespread primarily throughout the tropics, but also found in warm temperate regions of Europe, eastern Asia, and the Americas. This family is well known for its high economic importance for edible fruits and seeds, medicinal compounds, valuable timbers or resin and essential oil. This study contributes to the taxonomy of this family by pollen morphological studies of 59 genera and 127 species from all five tribes.
The Anacardiaceae pollen is stenopalynous and 25 pollen types are established mainly on different ornamentation patterns. Two groups of phylogenetic pollen morphological trends are discovered. The first group encompasses mostly members from the tribe Anacardideae, Semecarpeae, Spondideae and Rhoeae which are characterized by tri-(tetra-)zonocolporate and iso-(hetero-)polar pollen grains with a P/E ratio ranges from 0.79 to 2.03. The shape varies from oblate spheroidal to prolate, the polar outline varies from circular to triangular or interhexagonal and the equatorial outline is circular to elliptical. The aperture consists mostly of three ectocolpi (rarely four) with endocolpi or endopori. The exine structure is mostly tectate, psilate, striate, rugulate, reticulate, suprastriate or microechinate.
Group two comprises the tribe Rhoae and the Dobinea-type from the tribe Dobineae. The Parishia- and Dobinea-type are characterized by trizonocolporate and isopolar grains with short colpi and indistinct endocingulus whereas Pistacia-type is characterized by pantoporate and apolar grains. The exine structure is semitectate in the Dobinea- and Pistacia-type, but intectate in Parishia-type. The reticulum is homobrochate.

Personnel involved
Klaus Oeggl

Tipsuda Tangtragoon, Maejo University, Chiang Mai