From Plant Press, Vol. 20, No. 4, October 2017.
By Pedro Jiménez-Mejías
The Neotropic harbors one of the most striking biotas of the World. It has attracted the attention of researchers since the establishment of modern biology. Indeed, the understanding of Neotropical organisms has played a major role in the development of some of the most significant works in evolutionary biology, such as Humboldt’s basis of modern biogeography, the understanding of the Great American Interchange of fauna between North and South America during the Cenozoic Era, or the building of Darwin’s Theory of Evolution itself. In addition, the Neotropic harbors amazingly diverse biomes, including one of the most biodiverse communities on Earth, the Amazon rainforest. Moreover, it is extensively known that the formation of the Andes promoted diversification and speciation, not only by the creation of new environments on its slopes, but also as a result of the diverse influence the mountain range had on the surrounding territories.
Under such an overwhelming presence, some discrete organisms remain mostly unnoticed and poorly understood. Among them there are many Neotropical graminoids, i.e. grass-like plants. Graminoids are the main components of non-tree dominated ecosystems, such as prairies, savannahs, or wetlands, which cover a significant portion of South America. Despite the lack of showiness seen in other flowering plants, graminoids are extremely important in terms of biomass, serving as shelter and aliment to many creatures, as well as serving as resource foundations for human communities.
The genus Carex is one of these graminoids. Carex are sedges belonging to the family Cyperaceae, unlike true grasses which belong to family Poaceae. Under its current delimitation, Carex ranks as the third largest genus of flowering plants, containing close to 2,000 species, with new species discovered every year. Sedges of the genus Carex are cold-adapted, which is clearly depicted by its almost cosmopolitan distribution but total absence from tropical deserts and rainforest basins. The genus is known to have originated during the early Cenozoic probably in southeastern Asia. It spread and diversified through the northern hemisphere entering the southern hemisphere in South America, Africa, and Australasia by diverse colonization events. During its radiation Carex has always remained as a temperate element.