Pollen morphology in the Boragineae (Boraginaceae) in relation to the taxonomy of the tribe

The results of a comparative survey on pollen morphology in the Boraginene by means of light, scanning and transmission electron microscopy are presen ted and discussed in relation to the taxonomy of the tribe. Multivariate an alyses lead to the recognition of 15 pollen morphotypes for which a discrim inant key is proposed. The discriminatory characters concern mainly the ste reostructural and ultrastructural features of the grains, such as tectum sc ulpture and aperture morphology, while the number of apertures appears vari able within genera and even single species. Seven out of the 12 investigate d genera, as currently circumscribed, are matched by palynological data: An chusella, Borago, Brunnera, Elizaldia, Lithodora, Symphytum and Trachystemo n. On account of aperture shape, Lithodora is however closer to the Lithosp ermeae than to the Boragineae. Other genera, and in particular Nonea, show a wide variation in tectum ornamentation, shape of grains and number of ape rtures. Palynological data do not support a broad concept of the genus Anch usa, and point to the autonomy of the 'satellite' genera Hormuzakia, Gastro cotyle, Phyllocara, Pentaglottis and Cynoglottis.