The páramos of the northern South American Andes are characterized by extensive grasslands and the dominance of strange plants with stemmed rosettes, commonly known as frailejones. These plants are widely distributed and abundant in the high Andean forest and páramos of Colombia, Venezuela and, to a lesser extent, Ecuador, and the preservation of the páramo ecosystem depends largely on them. Almost every páramo harbors endemic species of frailejones, with only a few species occurring in multiple páramo localities.
In 1976 Don José Cuatrecasas, eminent Spanish botanist, classified all the frailejones species as the subtribe Espeletiinae Cuatrec. (Asteraceae: Millerieae). The subtribe has numerous synapomorphies, such as spiral leaf phyllotaxis; obpyramidal to prismatic shape of the achenes, which also are epappose; fertile female ray flowers and functionally male
disc flowers; pluriseriate
involucre and persistent pales of the
receptacle; thick and woody stems; xeromorphic structure; specialized life-forms; and a static chromosome number (n=19). Recent molecular evidence support the monophyly of this group.
Frailejones are distributed from 1,800 m in elevation up to the lower limit of the glaciers (4,700 m). Most of the species are dominant in various páramos, sometimes representing more than 40% of the plant cover. Local endemism at the specific level in Espeletiinae is extremely high (ca. 90%), possibly as a result of island-like radiation on a continental scale. Speciation of the group occurred very recently, most likely during the late Pliocene or early Pleistocene (2-4 my BP). Due to this remarkable diversity which appears to have evolved over a relatively short period of time, the group has been considered a classic example of rapid radiation in the tropics.
The more than 142 named species of the subtribe are grouped into eight genera: Carramboa, Coespeletia, Espeletia, Espeletiopsis, Libanothamnus, Paramiflos, Ruilopezia and Tamania. For the most updated list of species please check the nomenclator (Diazgranados, 2012), but don't forget to include the latest new species.
Bees (principally species of Bombus, Colletes and Apis) are the most frequent pollinators of Espeletiinae. Cypselae lack a
pappus and other disseminating devices, which limits long-distance dispersal. Wind or animals may disperse the achenes short distances but never more than 1-3 m from the parent plant, although light rains and small streams may disperse them longer distances. Hence, both pollination and seed dispersal suggest that there is a strong isolation by distance among different páramos, which are normally separated by several kilometers of areas unsuitable for frailejones species.
Most Espeletiinae species are of critical ecological importance because they contribute to regulating the hydrologic cycle, produce most of the biomass in these ecosystems, prevent soil erosion, and have key associations with more than 125 animal species. However, several species are in risk. Only in Colombia, where the extinction risk of these species has been evaluated, 36 species (46%) are listed as threatened, 16 are endangered and seven critically endangered.