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Abstract Detail


Lema-Suárez, Irene [1], Sahuquillo, Elvira [1], Loureiro, Joao [2], Castro, Silvia [3], Pimentel, Manuel [1].

The holy grasses in South America (Hierochloë R.Br. sect. Monoecia; Poaceae; Pooideae). Diversity and evolution of an isolated lineage.

The holy grasses (Hierochloë R.Br.) in South America are characterised by a monoecious floral structure that deviates from the andromonoecism common to all other Hierochloë. This morphological differentiation led to their inclusion in section Monoecia Connor, which forms a clearly defined clade within the otherwise poorly supported Hierochloë phylogeny. Section Monoecia comprises between 5 and 9 species, some of which are taxonomically dubious. We aim at clarifying the taxonomy and evolution of Hierochloë section Monoecia. More particular aims were: (i) to analyse morphological variation in the section; (ii) to unravel the phylogeny of the different species in sect. Monoecia and (iii) to assess the variation in DNA content in the section. Morphological and micro-anatomical traits were analysed. Numerical taxonomy tests including exploratory, clustering and multivariate analyses were conducted to ascertain if morphological variation is consistent with the taxonomy of the section. Parsimony and Bayesian analyses were run on nuclear and plastid DNA sequences obtained from 6 species of sect. Monoecia and 15 specimens obtained from non American Hierochloë taxa. Genome size was assessed using flow cytometry. The morphological variation observed is not entirely consistent with the current taxonomy of the section. Only the ecologically divergent species H. pusilla, H. juncifolia and H. quebrada could be characterized using the selected traits, whereas H. redolens, H. utriculata, H. altissima and H. gunckelii, whose ecology and distribution are partially overlapping, could not be differentiated based on the selected characters. The phylogenies built are consistent with the morphological results, and only H. pussilla, H. juncifolia and H. quebrada occupied supported independent positions in the trees. The geographically widespread H. redolens was recovered as non monophyletic, whereas H. utriculata, H. gunckelii and H. altissima joined the Chilean H. redolens populations in a polytomic clade. Genome size estimates revealed cytogenetic diversity within the section, with very similar values being obtained in H. redolens (Chilean populations), H. altissima (one population), H. utriculata, H. gunckelii and H. quebrada (17.9 - 20.42 pg), corresponding to the same ploidy level (hexaploidy). However, most H. altissima plants present a higher DNA content value (26.65-27.91 pg, duodecaploidy), indicating ploidy level diversity within this species. Hierochloë pusilla, H. juncifolia and H. spicata showed a rather lower DNA content value (12.9-14.9 pg), being tetraploid. These results contribute significantly to the taxonomy of sect. Monoecia, supporting some of the species but also highlighting the need for a more detailed taxonomic review of the others.

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1 - University of A Coruña, Plant Biology, Animal Biology and Ecology, Faculty of Sciences, Campus da Zapateira sn, A Coruña, E15008, Spain
2 - University of Coimbra, Centre for Functional Ecology, Calçada Martin de Freitas sn, Coimbra, 3000-456, Portugal
3 - Department Of Life Sciences, Faculty Of Science And Technology, Univer, PO Box 3046, Coimbra, N/A, 3001-401, Portugal

Hierochloƫ sect. Monoecia
South America
Numerical Taxonomy
Genome Size.

Presentation Type: Poster
Session: P, Systematics Section/ASPT Posters
Location: Exhibit Hall/Savannah International Trade and Convention Center
Date: Monday, August 1st, 2016
Time: 5:30 PM This poster will be presented at 6:15 pm. The Poster Session runs from 5:30 pm to 7:00 pm. Posters with odd poster numbers are presented at 5:30 pm, and posters with even poster numbers are presented at 6:15 pm.
Number: PSY020
Abstract ID:143
Candidate for Awards:None

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