STM Article Repository

The pollen grains of 22 species covering 11 genera are investigated. These selected species are represented by the two subfamilies Heliotropioideae and Boraginoideae with 7 tribes. Light and scanning electron microscopic techniques are followed. This work aims to introduce a well-developed identifying constant and valuable features of pollen grains. General pollen morphological characters are examined: the size, shape, polarity, apertures types & features, colpi characters, endoapertures and tectum characters. Two patterns of grains are observed; hetero- and homoaperturate. Results are significantly variant; grains are monads, mostly minute- or small-sized and prolate or subprolate. Endoapertures shape is lo- or lalongate. Eight pollen types and 2 subtypes are derived from the apertures types & features, and tectum characters. These results are consumed to describe different taxa. A palynological studying of the Boraginaceae is, however, of great taxonomic significance.