Unique aperture stratification in Carex (Cyperaceae) pollen

Abstract

Mature pollen usually has a conspicuously thick intine in the aperture regions, whereas in the interapertural area(s) the intine is thin. In Carex (and in other Cyperaceae with pseudomonads), usually five to six circular or elongated apertures (poroids) are present, one situated distally and the others equatorially. In the species studied here the situation is opposite: the apertures (poroids) are characterised by a very thin intine, whereas in the interapertural area(s) the intine is conspicu- ously thickened. A similar condition is only known for Vinca (Apocynaceae). A second unusual sporoderm feature in Carex relates to the foot layer. In the interapertural area(s) the foot layer is thin and discontinuous. The equatorial poroids exhibit a compact, thick and homogeneous foot layer, whereas the distal poroid is distinguished by an elaborated foot layer, structurally similar to a transfer-cell wall labyrinth. This unique elaborated foot layer in the distal poroid probably functions as a nutrimental passage between the tapetum and the maturing pollen. The pseudomonads are usually pear-shaped, sometimes spherical. Ornamenting elements are microechini, granules, and perforations, all sometimes placed on verrucae. © 2010 Collegium Palynologicum Scandinavicum.