Seed and seedling morphology : convergence of conditioning characters for plant survival in páramos

Abstract

ABSTRACT: Páramos are crucial ecosystems present in the Andean mountain forest. This ecosystem has a high diversity of plant species, dominated by grasslands, shrubs, rosettes, and various herbs, including Angiosperms, ferns, and Lycopodiophyta. Plants thriving in páramos face extreme conditions, including high-altitude air, low temperatures, and intense ultraviolet radiation. These plants have different traits that allow them to survive within this ecosystem. However, few studies have investigated about morphology and germination traits of seeds and seedlings from páramos. Our objective was to characterize the anatomy and histochemistry of the seeds, the dormancy class, and the morphology of the seedlings in 15 species of Colombian páramos. The anatomy of seeds of 15 species was described using microtome sections and light microscopy. Dormancy classes were determined using anatomical traits and Median Length of Germination (MLG). Also, we applied different treatments to break seed dormancy and analyzed seedlings' morphological development. Our findings reveal a higher prevalence of underdeveloped embryos within seeds of plants thriving in páramos. Among the species analyzed, underdeveloped embryos exhibit a wide range of morphological plasticity. Also, nine of the 15 analyzed species feature embryos or endosperms rich in protein storage. Seeds of 80% of the species analyzed exhibited dormancy, eight (53.3%) with Morphophysiological Dormancy (MPD), two (13.3%) have Physiophysical Dormancy (PY+PD), and two (13.3%) with Physiological Dormancy (PD). GA3 and punctured allow dormancy to be broken in some seeds. Our study sheds light on enigmatic anatomical, histochemical, and seed dormancy traits, contributing to understanding the reproductive biology and successional processes of páramos plants. Seeds of analyzed species have wide anatomical plasticity but with the presence of parallel traits such as an underdeveloped embryo and protein storing, which can be related to the survival of this species in drastic weather conditions and the development of morphophysiological dormancy.