Pollen morphology of the tribes Eritrichieae and Cynoglosseae (Boraginaceae) in the Iberian Peninsula and its taxonomic significance

DÍEZ, M. J. & VALDÉS, B., 1991. Pollen morphology of the tribes Eritrichieae and Cynoglosseae (Boraginaceae) in the Iberian Peninsula and its taxonomic significance.
The pollen morphology of 33 species of Boraginaceae from the Iberian Peninsula belonging to the tribes Eritrichieae and Cynoglosseae has been studied by light and scanning electron microscopy. The results confirm the eurypalinous character of this family, in which a large number of species can be recognized by their pollen characters.
The pollen of these two tribes is basically heterocolpate, a type which is very uncommon in the angiosperms, with 6, 8 or 10 apertures, sometimes with ectoapertures anastomosed at the equator (ectocingulum), or diorate, minute or small in size, outline elliptic or rectangular-elliptic in equatorial view, with or without a constriction at the equator, exine 0.5-1.0 urn thick and the tectum psilate with granules around the colpi. The similarity in shape and apertural system found in several genera such as Asperugo, Gyrocarion and Omphalodes, and some species of Myosotis, does not permit the two tribes to be distinguished on pollen characters. The generic limits of Cynoglossum and the infrageneric classification of Myosotis are discussed.