Morphology and anatomy of the exine in Saxifraga (Saxifragaceae)

Details of exine morphology (SEM studies of 132 species) and anatomy (TEM studies of 25 species) of Saxifraga are reported. The variation observed was compared with that found in an earlier survey. We suggest modifications to known types and subtypes and the addition of new ones, making a total of nine exine types and subtypes in Saxifraga. Taxonomic conclusions include the following. A novel exine type (Type 2.3), in which the single tectum has numerous microchannels, is a putative synapomorphy for sects. Heterisia and Irregulares. At least three species from sect. Ciliatae, viz., S. lychnitis, S. oresbia from ser. Lychnitidae, and S. nigroglandulifera from ser. Nutantes, have a novel type with a perforate-reticulate or perforate-rugulate tectum. Species from the rest of the section are uniformly finely striate. Section Saxifraga has Type 2.1, with a single tectum, Type 4.3, with a double tectum, and Type 2.2, which is intermediate to various extents. The origin of Types 2.1 and 2.2 from Type 4.3 is suggested. Within sect. Saxifraga subsect. Triplinervium, S. wahlenbergii is unique in possessing pollen with a secondary tectum (Type 4.3), resembling the exine of S. androsacea in subsect. Holophyllae. On this and other grounds, we support the transference of S. wahlenbergii to the latter subsection. Himalayan species with opposite rather than alternate leaves that were formerly assigned to sect. Porphyrion subsect. Oppositifoliae, have exines with supratectal ornamentation similar to that in subsect. Kabschia; in this respect they are unlike the European species with opposite leaves, which lack this ornamentation. Among the species with chalk-glands, exines lacking supratectal ornamentation are restricted to European species, viz. those in sect. Porphyrion subsects. Engleria and Oppositifoliae, and S. florulenta, offering morphological support for the transfer of the latter species to sect. Porphyrion. Saxifragella is recognised as a new section of the genus.

Palynology of the Genus Stachytarpheta Vahl. (Verbenaceae)

The exine morphology of pollen grains of Stachytarpheta indica (Linn.) Vahl, Stachytarpheta cayennensis (Rich.) Vahl and Stachytarpheta angustifolia (Mill.) Vahl is reported. This study was carried out with a light microscope. Pollen grains from fresh anthers were collected and aceolysed. Statistical analysis used to analyse the data collected include cluster analysis, correlation analysis, similarity and distance indices. The pollen grains are spheroidal to oblate to sub-oblate in shape. They are aperturate, both colpate and porate. Tricolpate types occur most frequently, acolpate, monocolpate, bicolpate and tetracolpate types less frequently. The multicolpate and multiporate attributes in all the species indicate that the genus is not primitive in evolutionary history and this species probably, evolved around in the same time. According to the size, the pollen grains of the genus falls into groups permagna (pollen diameter 100-200 μm) and giganta (pollen diameter greater than 200 μm). S. cayennensis and S. anguistifolia belong to group permagna and S. indica only in the group giganta. This separates S. indica from the other two species. The large pollen grain size in the genus clearly supports the fact that the flowers in the genus are more insect-and-bird pollinated than wind pollinated. The similarity and distance indices of the species showed that S. cayennensis and S. angustifolia are the closest. S. indica is closer to S. angustifolia but farther from S. cayennensis.

Pollen morphology of North American species of Antennaria (Asteraceae: Inuleae)

The pollen of 90 individuals representing 28 species and subspecies in the genus Antennaria is described through the use of light and scanning electron microscopy. Two morphological groupings separated on the basis of exine morphology are evident from cluster analysis. One group consists of those species and subspecies in which the exine is perforate and the other group consists of those individuals in which the exine is not perforate (perforate-reticulate or striate-perforate-reticulate). These two pollen morphological groups do not correspond with previously defined groupings based on morphology or cytogenetics. Both large (> 19 μm in diameter) and small pollen grains occur in each of the cluster groups. Similarly, both long- (> 2 μm) and short-spined individuals occur in each of the cluster groups. Used in combination, these characters do however exhibit some sectional affinities. Section Alpinae is characterized by pollen grains with long spines. Section Dioicae is characterized by small pollen grains. Section Plantaginifoliae is characterized by large pollen grains with long spines. Species included in sections other than these are not consistent in their pollen morphology. The pollen groups recognized in this preliminary study form a basis for future studies at the geographic or population level.