The emergence of core eudicots: new floral evidence from the earliest Late Cretaceous.

Eudicots, the most diverse of the three major clades of living angiosperms, are first recognized in the latest Barremian-earliest Aptian. All Early Cretaceous forms appear to be related to species-poor lineages that diverged before the rise of core eudicots, which today comprise more than 70% of angiosperm species. Here, we report the discovery of a well-preserved flower, Caliciflora mauldinensis, from the earliest Late Cretaceous, with unequivocal core eudicot features, including five sepals, five petals and two whorls of stamens borne on the rim of a floral cup containing three free carpels. Pollen is tricolporate. Carpels mature into follicular fruitlets. This character combination suggests a phylogenetic position among rosids, but more specific assignment is precluded by complex patterns of character evolution among the very large number of potentially relevant extant taxa. The whorled floral organization is consistent with ideas that this stable pattern evolved early and was a prerequisite for more integrated patterns of floral architecture that evolved later. However, limited floral synorganization in Caliciflora and all earlier eudicot flowers recognized so far, calls into question hypotheses that substantial diversification of core eudicots had already occurred by the end of the Early Cretaceous.

Rungiafangdingiana (Acanthaceae), a new species from Guangxi, China.

Rungiafangdingiana, a new species of Acanthaceae from Guangxi, China is described and illustrated. This new species belongs to Rungiasect.Rungia, and resembles R.sinothailandica and R.burmanica in the erect perennial herbaceous habit, elliptic leaves and inflorescence form, but differs mainly by the indumentum and the morphology of the bracts and corolla. The pollen and seed micromorphology of this new species are studied, with photographs and a line drawing provided.

Pollen morphology of the genera Hidalgoa and Dahlia (Coreopsideae, Asteraceae): implications for taxonomy.

Hidalgoa and Dahlia are two closely related genera in Asteraceae, tribe Coreopsideae whose limits need to be clarified. Pollen morphology has been useful for delimitation at the genus level in this family. To better define these genera, the morphology of pollen grains was observed and measured using light and scanning electron microscopy. The pollen grains of 25 species of Dahlia and Hidalgoa were acetolyzed and analyzed. Pollen is tricorporate in most of the species studied, although in a few species in Dahlia, grains were found to be hexacolporate. The most outstanding differentiating characters among species of Dahlia and Hidalgoa are colpus length (greater in Hidalgoa) and shape of spines (conical in Hidalgoa). In addition, lalongate ora are larger in Hidalgoa than in Dahlia. A PCA analysis of thirteen pollen characters, identified species of Hidalgoa in a discrete group and Dahliacuspidata as an outlier. These distinctive attributes in pollen morphology support the idea that pollen morphology is useful for delimitation at the generic level in the Dahlia clade. Further evidence from other sources, genetic or anatomical, might contribute to demarcating Dahlia and Hidalgoa, and provide insight into the family's evolutionary history.

Use of scanning electron microscopy to analyze sculpturing pattern and internal features of pollen grain wall in some members of Astragaleae (subfamily: Papilionoidae).

Palynological features of tribe Astagaleae L. have been observed with scanning electron microscopy (SEM), to assess features that can be used to re-examine the placement and taxonomic position of tribe. The palynomorph attributes of 10 species included in three genera of Astragaleae (Astragalus L., Glycyrrhiza L., and Oxytropis DC.) are investigated. The assignment of genus Oxytropis in tribe Astragaleae was also reevaluated based on pollen characters. Pollen appear to be prolate, prolate-spheroidal, and subprolate. Polar axis size (P) varies from 31.3 µm ±1 to 17.5 µm ±1.4 and equatorial axis size (E) varies from 22.2 µm ±1.8 to 13.1 µm ±0.9. Prominent apertures found consistently dispersed along the surface of pollen. Three kinds of ornamentation pattern were recorded, that is, reticulate or reticulate-perforate and perforate. The studied species display variation in equatorial and polar diameter, aperturation and sculpturing pattern, exine thickness, and pollen shape. On the basis of descriptive pollen features, a dichotomous taxonomic key and UPGMA analysis has been made for effortless and quick identification. The study concluded that disparities of the entire features are typically unrelenting and concerned with the species and shows potential systematic significance. The combination of palynological attributes in association with additional traits has prospective for systematic identification at species and genus level.