Late glacial and Holocene vegetation, Indian monsoon and westerly circulation in the Trans-Himalaya recorded in the lacustrine pollen sequence from Tso Kar, Ladakh, NW India

The Polygonaceae (40-50 genera and approximately 1,100 species) are characterized by the presence of an ocrea, an hyaline or membranous tubular sheath, derived from the fusion of the stipules. Their classifi cation is based principally on macromorphological characters. The broad Poly- gonum s.l. is a much debated genus which has been variously interpreted in the literature: its relation to associated genera is not clear and moreover, it has been subdivided into numerous more natural taxa considered at the rank of genus, subgenus or section. In the present study, using analysis of the rbcL sequence the monophyly of the various taxa that Polygonum s.l. has been subdivided are investigated by focusing on the species present in Europe in order to reach a classifi cation more in line with the molecular data. The phylogenetic tree obtained with the maximum parsimony method confi rms that Polygona- ceae is monophyletic, however, the subfamily Polygonoideae seems to be paraphyletic as it includes the Eriogonoideae. On the basis of the principal clades identifi ed the restriction of the Polygonoideae to only those taxa with an herbaceous habit is confi rmed and a new classifi cation articulated in 4 tribes is proposed: 1) Polygoneae, subdivided into Polygoninae (Atraphaxis, Polygonum -incl. Polygonella- and, probably, Calligonum, Oxygonum, Parapteropyrum and Pteropyrum) and Reynoutriinae (Fal- lopia, Homalocladium, Muehlenbeckia, ×Reyllopia, Reynoutria) as well as an incertae sedis genus (Knorringia); 2) Persicarieae, subdivided into Persicariinae subtrib. nov. (Persicaria) and Koenigii- nae (Aconogonum, Bistorta, Koenigia, Rubrivena); 3) Fagopyreae (Fagopyrum, Harpagocarpus and, probably, Eskemukerjea and Pteroxygonum); 4) Rumiceae (Emex, Oxyria, Rheum, Rumex). Lastly new combinations and/or new names are proposed in the genus ×Reyllopia, Persicaria and Rubrivena.

Molecular phylogeny of Polygonum L. s.l. (Polygonoideae, Polygonaceae), focusing on European taxa: preliminary results and systematic considerations based on rbcL plastidial sequence data

Molecular phylogeny of Koenigia L. (Polygonaceae: Persicarieae): implications for classification, character evolution and biogeography.

Pollen morphology of 12 species belonging to the genus Polygonum L., (Polygonaceae) from Pakistan has been investigated by light and scanning electron microscopy. Polygonum L., is an eurypalynous genus and four types of surface ornamentation (granulate, granulate-coarsely reticulate, dimorphic exine and variable pattern of ornamentation in polar and equatorial view) have been observed under scanning electron microscope. The variation in exine ultrastructure makes it possible to distinguish four pollen types (Patulum type, Plebijum type, Cognatum type and Avicularia type). Pollen morphology within the genus proved to be useful for the specific delimitation.

Pollen morphology of selected Polygonum L. species (Polygonaceae) from Pakistan and its taxonomic significance.

This study, the fifth in a series investigating palynological characters in angiosperms, aims to explore the distribution of states for 19 pollen characters on five early diverging orders of Superasteridae (Berberidopsidales, Caryophyllales, Cornales, Ericales, and Santalales) plus Dilleniales. To illustrate the character states found in the pollen of this group, we examined pollen grains of 15 species exemplifying 15 families across all studied orders using light, scanning, and transmission electron microscopy. We reconstructed the phylogeny of the early diverging Superasteridae and related taxa with eight genetic markers for 172 genera, using maximum likelihood (ML) analysis. Nineteen pollen characters were coded for the genera used in this phylogeny and compiled into two morphological matrices using two coding strategies. The characters were then optimized on the newly generated ML tree plus two constrained trees differing in the position of Dilleniales, using three methods of inference. Taxa in this grade show a striking diversity of pollen morphologies, particularly in certain characters such as size, tectum sculpture, and aperture number. The plesiomorphic condition for the early diverging Superasteridae is unambiguously and consistently inferred to comprise monad-dispersed, isopolar, spheroidal, circular in outline, equatorially arranged, tricolpate pollen grains with granular aperture membranes, a smooth tectum, and endexine present. We identify diagnostic character states and synapomorphies for several monophyletic groups, and explore the palynological evidence that may shed light on some unresolved relationships. For example, the hypothesis that Dilleniales is sister to Superrosidae is better supported than alternative hypotheses, being consistent with a number of shared palynological state changes including transitions to presence of costae, reticulate tectum, and columellar infratectum structure. Across this part of the angiosperm phylogeny, most state transitions occur repeatedly, and their frequency varies among both clades and characters. We discuss the impact of optimization method, tree topology, and coding strategy upon ancestral state reconstruction.

https://bioone.org/journals/annals-of-the-missouri-botanical-garden/volume-103/issue-1/2017017/Evolution-of-Angiosperm-Pollen-5-Early-Diverging-Superasteridae-Berberidopsidales-Caryophyllales/10.3417/2017017.pdf

Evolution of Angiosperm Pollen. 5. Early Diverging Superasteridae (Berberidopsidales, Caryophyllales, Cornales, Ericales, and Santalales) plus Dilleniales

Tao Han-Lin

Papers

Pollen morphology of Polygonum section Aconogonon Meisn. in China