Morphoanatomy and leaf biomass in Espeletia standleyana A.C.Sm. and Espeletia santanderensis A.C.Sm. in a northeastern Colombian paramo

Abstract The adaptive responses of Espeletia standleyana and E. santanderensis populations in a paramo in Northeastern Colombia (3350 m a.s.l.), were studied to characterize their spatial segregation. Their anatomical, morphofunctional and leaf biomass characteristics were determined and compared. We found that many traits such as depth of the stomatal crypts, number of vascular bundles, leaf and peduncle xylem vessel diameters, thickness of the mesophyll, leaf area, rosette height and diameter, leaf water content, leaf area index, and leaf biomass were significantly higher in E. standleyana (P< 0.05). Meanwhile, the diameter of the vascular bundles, width of stomatal crypts, number of leaves, specific leaf area, and percentage of sclerophylly were higher in E. santanderensis (P<0.05). Multifactorial segregation indicated highly differential expressions in their morphofunctional and leaf biomass characteristics, evidencing adaptations to their microhabitats. E. standleyana showed xeromorphic characters in response to the greater ambient fluctuations typical of the paramo, while E. santanderensis responded with scleromorphic traits related to lower soil organic matter and water content, characteristic of the high Andean forest-paramo ecotone. The high spatial heterogeneity of the paramos allows the development of microclimatic and edaphic mosaics that determine population segregation of these growth forms.