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Morphological Innovations in Poales

Re-evaluating morphological innovations in the economically important grass order (Poales), including reproductive structures.
Pharus latifolius (Poaceae), SEM developing spikelet. Scale bar = 100µm. Photo: M.G. Sajo.

The monocot order Poales, with c. 20 000 species, represents more than one third of all monocots and includes many economically highly significant crops. Research over the past two decades has broadened the circumscription of the order to include not only Poaceae (grasses) and Cyperaceae (sedges) and their respective allies, but also several smaller families such as Bromeliaceae, Rapateaceae, Typhaceae, Xyridaceae and Eriocaulaceae. It remains questionable whether the small and phylogenetically isolated family Dasypogonaceae should also be included in the order. The most species-rich lineages of Poales are associated with sunny, seasonally arid or generally dry (savanna and steppe grasslands and heathlands) or epiphytic habitats, and they often contain annual species, or species with CO2-concentrating mechanisms such as C4 photosynthesis and crassulacean acid metabolism (CAM).

The improved phylogenetic background for Poales allows us to address questions about the morphological innovations that promoted the considerable species richness of the larger families, especially Poaceae. Our current primary foci are (1) the evolution of silica bodies in grasses, in which these cell inclusions are correlated with the evolution of grazing animals, and (2) the evolution of floral and seed structures.

This is a long-term project that is based in the Jodrell Laboratory and involves both cross-departmental and international collaboration. Ongoing projected research output is one publication per year.

Key papers published since 2006.
1. Sajo, M.G., Longhi-Wagner, H. & Rudall, P.J. (2007). Floral development and embryology in the early-divergent grass Pharus. International Journal of Plant Sciences 168: 181–191.
2. Sajo, M.G., Longhi-Wagner, H. & Rudall,P.J. (2008). Reproductive morphology of the early-divergent grass Streptochaeta and its bearing on the homologies of the grass spikelet. Plant Systematics and Evolution 275: 245–255.
3. Sokoloff, D.D., Remizova, M.V., Linder, H.P. & Rudall, P.J. (2008). Morphological nature of reproductive units and interpretation of inflorescences in Centrolepidaceae (Poales). Bulletin Tver State University, Series Biology and Ecology 25 (9): 257–262.
4. Sokoloff, D.D., Remizowa, M.V. & Rudall, P.J. (2009). A new species of Centrolepis (Centrolepidaceae: Poales) from Northern Australia, with remarkable inflorescence architecture. Botanicheskii. Zhurnal. 1: 92–100.
5. Sajo, M.G., Furness, C.A. & Rudall, P.J. (2009). Microsporogenesis is simultaneous in the early-divergent grass Streptochaeta, but successive in the closest grass relative Ecdeiocolea. Grana 48: 27–37.
6. Smith, S.Y., Collinson, M.E., Simpson, D.A., Rudall, P.J., Marone, F. & Stampanoni, M. (2009). Elucidating the affinities and habitat of ancient, widespread Cyperaceae: Volkeria messelensis gen. et sp. nov., a fossil mapanioid sedge from the Eocene of Europe. American Journal of Botany 96: 1506–1518.
7. Sokoloff, D.D., Remizowa, M.V., Linder, H.P. & Rudall, P.J. (2009). Morphology and development of the gynoecium in Centrolepidaceae: the most remarkable range of variation in Poales. American Journal of Botany 96: 1925–1940.
8. Sokoloff, D.D., Remizowa M. V., Linder, H.P., Macfarlane, T.D. &  Rudall, P.J. (2010). Arrangement of reproductive units in Centrolepis (Centrolepidaceae, Poales): cincinnus or spikelet? Pages 425–436 in Diversity, phylogeny, and evolution in the monocotyledons. Eds. Barfod, A., Davis, J.I., Petersen, G. & Seberg, O. Aarhus University Press, Denmark.
9. Smith, S.Y., Collinson, M.E., Rudall, P.J. & Simpson, D.A. (2010) Cretaceous and Paleogene fossil record of Poales: review and current research. Pages 333–356 in Diversity, phylogeny, and evolution in the monocotyledons. Eds. Barfod, A., Davis, J.I., Petersen, G. & Seberg, O. Aarhus University Press, Denmark.

Project partners and collaborators


Briggs, B. (Sydney)
Macfarlane, T. (Western Australia)
Conran, J. (University of Adelaide)



 Graça, S.M. (UNESP)


Sokoloff, D. and Remizowa, M. (University of Moscow)


Linder, H.P. (University of Zurich)


Collinson, M. and Smith, S. (Royal Holloway)


Davis, J.I. (Cornell University)
Kellogg, E. (University of Missouri)

Project funders


Mostly core; also Bentham-Moxon Trust, Royal Society

Project team

Herbarium, Library, Art & Archives

David Simpson, Maria Vorontsova

Jodrell Laboratory

Carol Furness, Chrissie Prychid, Paula Rudall

Seed Conservation DepartmentWolfgang Stuppy
Science Teams: