Morphological, palynological, and anatomical investigations of Hieracium L. (Lactuceae, Asteraceae) in Pakistan.

Morphology, leaf anatomical features and pollen grain characteristics of the genus Hieracium (Asteraceae: Lactuceae) have been investigated and illustrated for the first time in Pakistan. Hieracium L. and Pilosella Hill, are recognized as separate genera. All Hieracium species are perennial rhizomatous herbs. In this study five species, i.e. Hieracium bichlorophyllum, H. diaphanoides, H. umbellatum, H. virosum, and H. vulgatum are described for Pakistan. The stem surface is glabrous in H. diaphanoides and H. umbellatum, while sparse echinulate and stellate hairs are also present in H. umbellatum. Hieracium bichlorophyllum has scabrous hairs, while stellate hairs are present in H. vulgatum. Basal leaves are sessile in all species but subsessile in H. vulgatum. Leaves are bifacial and stomata cells are staurocytic and amphianisocytic. The pollen type of the investigated species is trizonocolporate and tetrazonocolporate. [ABSTRACT FROM AUTHOR]