Epiphytic plants
Epiphytic plants Epiphytic plants are plants that evolved by growing on trees, therefore they have no contact with the ground, and feed on humidity, rainwater and nutrients taken from decomposing leaves.
Tree species in humid tropical forests are often covered with epiphytes.
Contrary to popular belief, they are not parasitic plants, in fact they do not absorb nutrients from the host plant but only use it as a support.
More than 2,000 epiphytes can be found on a single tree. They make up a third of the total tree weight and 40% of the leaf biomass in some forests.
89% of terrestrial epiphytic species (about 24,000) are flowering plants such as orchids.
The second largest group are the leptosporangiate ferns, with about 2800 species (10% of the epiphytes). In fact, about a third of all ferns are epiphytes. The third largest group is Lycopodiaceae, with 180 species, followed by a handful of species in each of the Selaginellaceae, other ferns, gnetophytes, and cycads.
They are not parasites because they do not absorb nutrients
-High up in the canopy, epiphytes are better able to access strong tropical sunlight
-Designed for airborne living
Bromeliads can hold over eight liters of water in the basins formed in their stiff, upturned funnel-shaped leaves
-These waterholes act as nurseries for frog tadpoles and insect larvae specifically adapted to life in this small niche
Where do epiphytic plants live?
Numerous epiphytic species are found in the tropical forests, particularly in the hyper-humid areas between 1,000 and 2,000 m. In temperate zones, outside those regions with humid summers such as in eastern Asia, epiphytes are very rare and represented only by a few individuals of species usually found on rocks.
The reason generally given for the lack of epiphytes in temperate zones is the severe winter cold, and dry summers experienced by most temperate zones.
There is, however, an immense amount of activity among the invisible epiphylls like bacteria and fungi that coat the branches and foliage in the canopy.
Where are most epiphytic plants found?
Large epiphyte assemblages occur most abundantly in moist tropical forests. Mosses and lichens can be found in almost all biomes. In Europe there are no dedicated epiphytic plants that use roots, but rich assemblages of mosses and lichens. They grow on trees in wetlands, and some ferns grow epiphytes along branches and on rocks.
Epiphytic plants produce nutrients
Epiphytic plants are responsible for the production of many nutrients. As a result, the rainwater that reaches the undergrowth is no longer pure. It is enriched in nitrogen, phosphorus, potassium, calcium and magnesium, to name only the most important elements that plants absorb. According to recent studies, it seems that 30 percent of the nitrogen circulating in the forest is produced by epiphytes in two ways: by direct fixation by cyanobacteria (blue algae) and by decomposition of all the epiphytic flora.
The minerals are absorbed directly by the leaves and branches, through the thin cuticle which covers the epidermis, and probably also through the hairs which often abound on the small herbaceous plants of the undergrowth.
The minerals are absorbed directly by the leaves and branches, through the thin cuticle which covers the epidermis, and probably also through the hairs which often abound on the small herbaceous plants of the undergrowth.
Where do epiphytic plants get their water from?
Epiphytes are not connected to the soil, and consequently they must obtain nutrients from other sources, such as fog, dew, rain and mist, or from nutrients released by plants rooted in the soil by decomposition or leaching and nitrogen fixation.
Epiphytic plants attached to their hosts high in the canopy have an advantage over soil-restricted grasses where there is less light and herbivores can be more active. Epiphytic plants are also important for some animals that can live in their water tanks, such as some types of frogs and arthropods.
Epiphytes can have a significant effect on their host’s microenvironment and the ecosystems in which they are abundant, as they retain water in the canopy and reduce water supply to the soil. Some non-vascular epiphytes such as lichens and mosses are well known for their ability to rapidly absorb water. Epiphytes create a significantly cooler and wetter environment in the canopy of the host plant, potentially greatly reducing water loss by the host through transpiration.
Recent increases in epiphyte abundance have been linked to excess nitrogen released into the environment from farm runoff and rainwater. The high abundance of epiphytes is considered to be detrimental to the plants they grow on often causing damage or death, particularly in seagrasses. This is because too many epiphytes can block access to sunlight or nutrients.
In the forests
Under the upper canopy of the forests, the cobweb of large oblique branches of the trees is found. On tall trees in tropical forests, the average trunk height measures 60 to 70 m and the crown 20 to 25 m. In the latter portion, the branches are covered with angiosperms (flowering plants), ferns, mosses, liver plants and lichens, as well as unicellular algae, fungi and bacteria. It is along these branches, often among the mosses, that better known epiphytes such as ferns, orchids and many Bromeliads and Araceae can be found.
Where the larger branches diverge from the trunk, the accumulation of humus and mechanical resistance allow larger epiphytes to take hold, such as Philodendron, Platycerium, Asplenium and Grammatophyllum species. In addition to the herbaceous species, there are numerous shrubby epiphytes of the Melastomataceae family, with the enormous genus Medinilla.
Epiphytic Cactaceae are abundant, mainly in the genera Rhipsalis, Epiphyllum and Schlumbergera, Aeschynanthus.
The Asplenium nidus ferns can be found on trunks and branches, usually a few meters from the ground. Its funnel shape allows humus to accumulate. This funnel created by the foliage of A. nidus reaches a diameter of one meter. The plants of the undergrowth: The final layer that descends from the crown to the undergrowth is represented by the herbaceous epiphytes that colonize the first meters of the tree trunks. These species are numerous, especially in America where the Bromeliaceae of the undergrowth and middle forest areas include various species of the genera Guzmania, Vriesea, Aechmea and Neoregelia. Among the Araceae, epiphytic species such as Philodendron and Anthurium species ( this genus includes over 800 species) tend to grow in these areas at mid-height. Also along the base of the trunk are various Peperomias and some species of Begonias. The important thing for our crops is to understand how high they live in nature. The lower the plant is, close to the subsoil, the more the plant will need less intense light. An integrated ecosystem, symbiosis between living beings
There are various collaborations between epiphytic plants and animals, an example is that of myrmecodia plants with some ants. Inside the core of the epiphytic plant there is a network of chambers that house ants, which in exchange provide nutrients for the plant.
Epiphytes obtain water from rain and water vapor in the air; most absorb water with their roots although many have specialized with leaves that also absorb humidity. While some minerals are obtained directly from rain, the nutrients are generally absorbed by the debris that accumulates on the supporting plants. Given their restricted habitat requirements, many epiphytes rely on wind for seed dispersal and have feathery or powdery seeds. Animal dispersal is also common, and a number of species have edible fruits with seeds that are dispersed by birds and other tree-dwelling animals.
