Palms are abundant and diverse in tropical forests, but nowhere more conspicuous than in the Neotropical rainforests. There, they are structured in communities with up to 50 species and over 10,000 individuals per hectare. Palms. Are omnipresent and are found in both inundated and terra firme habitats. They are represented by a variety of life-forms from small acaulescent understory palms to large canopy species with massive trunks. Many palms produce fruits throughout the year and therefore serve as key-stone species that help feed many animals through the season when other plants produce few fruits.
Ferns and lycophytes are are vascular plants found in a variety of ecosystems, from deserts to tropical forests but most species are tropical (~75%). They are commonly found in Amazonian forests, from the canopy layer (as epiphytes) to the understory (as terrestrial, climbers or epiphytes). Ferns produces spores that are mainly wind dispersed and very small (0.05 mm in diameter), produced in great quantities (from a thousand to a billion per plant during each reproductive period).
Ferns are a very old lineage and the first fossils recognized are around 425 million years old, from the Middle Silurian period. Beginning with the Carboniferous (around 360 million years ago) the ferns radiated and became very diverse and dominated terrestrial ecosystems. The rise and spread of the angiosperms (flowering plants) during the Mesozoic is associated with the decline of the majority of ferns that make up the fossil records.
In Amazonia, the main use by natives is medicinal. They are used to cure diarrhea and stomach ache (Adiantum, Bolbitis, Selaginella), general aches and pains (Polybotrya), toothache (Cyathea), common cold, kidney problems (Equisetum), to aid healing of wounds (Campyloneuron, Lomariopsis), reduce swelling, as well as veterinary uses (Cyathea, Selaginella). While many species of ferns have ornamental potential, few are actually cultivated.
Most fern species are strongly associated to specific habitats, and thus, they are important indicators of environmental conditions. More over, ferns are relatively easy to find, collect and identify in the field and are diverse. Thus, since the 1970s, ferns have been used in inventories in Amazonia as biodiversity indicators and is a particularly interesting group to help understanding Amazonian biogeography.