An epiphyte is a non-parasitic plant that does not have direct contact with the ground surface, and that grows on other plants, usually woody plants, feeding on its own and using the branches and trunks of trees and shrubs only for attachment. Trees on which epiphytes grow are called phorophytes. 

Fungi, algae, lichens and about 10% of vascular plants (Tracheophyta) grow this way. The latter number more than 28,000 species in 876 genera belonging to 84 families. The most abundant epiphytes are found in the Orchidaceae, with 13 950 species in 876 genera, the Araceae, with 1349 species in 13 genera, and the Bromeliaceae, with 1144 species in 26 genera.

Most of these species are found in moist tropical forests in the Neotropics - South and Central America and the lowlands of Mexico. Fewer in Asia and Africa. Some epiphytes are found in dry areas in the forests of Mexico and Peru. Distribution and abundance are determined by humidity, tree size and bark texture. Epiphyte habitats are in the tree canopy.

Classification based on occurrence, mode of development and life form.

Accidental epiphytes (ephemeral or pseudo). These are individuals of spp. that are normally terrestrial but have a dispersal method which enables disseminules to be deposited in non-terrestrial sites (usually humus accumulations) which afford at least temporary conditions suitable fur germination and early growth. Such plants most often die before maturity owing to their lack of adaptation to epiphytic conditions, especially in regard to water relations.

Casual epiphytes (occasional or facultative) are similar to the above except that they are better adapted to a deficiency of water and nutrients. They therefore more effectively survive and mature and are more common as epiphytes than those in the accidental class. At the same time, most individuals of these spp., are typical terrestrials. 

Typical (true or holoepiphytes) are autotrophic spp. that normally pass their whole life cycle perched on another plant, the immediate source of all mineral nutrients being non terrestrial. 

Hemi-epiphytes (also lian-epiphytes): 

Primary hemi-epiphytes – germinate and establish as epiphytes but send roots to the ground whence most nutrients are subsequently derived, enabling full growth and maturation as a terrestrial plant. 

Secondary hemi-epiphytes – are plants that germinate and establish terrestrially, climb and presumably absorb water and nutrients via adventitious roots and eventually lose connection with the ground but continue growth epiphytically. 

Semi-epiphytic climbers – vines or vine-like plants that begin life as typical terrestrials but climb by adventitious roots, some of these functioning in water and mineral uptake roles as well as anchorage. These are like secondary hemi-epiphytes but do not become detached from the ground

Lithophytes (rupicoles, saxicoles, epiliths, rupestral plants) as for typical, but growing on a rock substrate; they are usually more tolerant of terrestrial conditions. Typical epiphytes will, under certain conditions, occasionally grow lithophytically, and rarely vice versa also. 

Classification based on physiognomy or growth form; groupings are not necessarily mutually exclusive. 

Woody Plants 

Shrub epiphytes (dendroepiphyta) – woody plants under 5 m tall, either branching from a single, basal, or multi-stemmed from the base and often layering (rooting where stems contactsuitable substrate). 

Herbs

Creeping epiphytes (mobiligenuui-epiphyta) have primary stems, growing appressed, or close and parallel to the substrate and attached to it by creeping adventitious roots. 

Long-creeping epiphytes (reptata remota) – vine-like, travelling relatively rapidly and far re position on substrate and in the microhabitat.

Medium-creeping epiphytes have leaves or secondary stems clearly spaced but not to the extent of being vine-like.

Short-creeping epiphytes (reptata densa, caespitosa) – those with primary stems contracted such that adjacent leaf stalks or secondary stem bases are in contact (very short-creeping).

Sedentary epiphytes – those which establish at a given point with the primary stem and main perennating buds growing into the air and not along the substrate and hence are of fixed position. 

Fruticose herb epiphytes have the general growth habit of shrubs but are non-woody to semi-woody. 

Rosette epiphytes (fascicularis, rosulate plants) have vertical stems with very short internodes. 

Fanplants also have very contracted stems but leaves are in two ranks.  

Tangle epiphytes are those which grow away from the substrate after establishing on it and thence most roots become aerial, such that the mature plant becomes a tangle of roots, stems, leaves and inflorescences.

Catchment epiphytes are those specialised to catch water and litter from a relatively large area and channel this to a central holding container. Nest-forming epiphytes (bracket epiphytes) catch leaf, twig, in florescence etc. debris and concentrate and compact this between successive leaves which also eventually die and add to the mass. 

Tankplant epiphytes (cistern epiphytes) – rosettes with leaf bases forming· a waterproof receptacle which holds free water, as well as debris. 

Atmospheric (aerial) epiphytes – many epiphytes appear to use the phorophyte for little more than anchorage since most of their absorbing organs, i.e. roots in orchids, or, in many bromeliads, foliar trichomes, are not in contact with the substrate and apparently derive their mineral nutrientsfrom rainwater and canopy throughfall. pseudobulbous or fleshy-caned. 

Epiphytes are adapted to collect and hold water. The encrusted leaves of some bromeliads form a dense scrotum with a tightly packed reservoir in the centre, where water is collected and retained for long periods. Other leaves are covered with hairs and scales (Tillandsia spp.) that absorb moisture from the air. The aerial roots do the same, as the humidity of the ambient air is 99 per cent.

Epiphytes are difficult to study because of their unusual habitats in the tree canopy. In the 19th century, the botanist Andreas Franz Wilhelm Schimper was interested in these plants in Central America, and in 1940 – Rembo, a clergyman living in southern Brazil. In 1966 they were studied in the forests of Micronesia by T. Hosokawa. The most intensive work has been carried out since 1980, when climbing equipment was introduced. 

The vision of the VU Botanic Garden is to assemble a collection of epiphytic plants that reflects their systematic, life form and geographical diversity.

In the extant plant lists of the VU Garden, we find that the orchid Epidendrum secundum Jack was introduced in 1810. Several species of facultative epiphytes, such as the Davallia canariensis (L.) Sm. and the Hoya carnosa (L.fil.) R.Br.), were cultivated in the greenhouses of the garden in 1840. The 1929 lists include the Monstera sdeliciosa Liebm. Epiphytic cacti have been cultivated since 1953: the Schlumbergera truncata (Haw.) Moran, various species of Rhipsalis spp.

		Plants of the Bromeliaceae family Many bromeliads are found on the branches of trees in humid tropical forests. They occur naturally in Central America. Their leaves are linear or linear-lanceolate, forming dense fronds with a central receptacle for water storage. They are monocarpic and flower once in their lifetime. The flowers are small, short-lived and concentrated in the form of a few or heads. They contain leaf-like bracts which remain coloured for several months. Once the flowers have set, these plants produce stem suckers that live until they flower.
		Platycerium bifurcatum (Cav.) C.Chr. This fern is common in tropical and subtropical forests in Australia. It has a branched rhizome. The leaves are twofold: the sterile ones are circular, encircling the rhizome and the branch of the tree on which they attach, and the others produce sporangia. The latter are bluish-green, leathery, fan-shaped, and resemble antlers. The sterile leaves are short-lived and dry out quite quickly. As the new leaves grow, they cover the old ones and take the remaining nutrients from them. Water is drawn from the ambient air by the fuzz on the leaves and stored in the shriveled old leaves.
		Rhipsalis pilocarpa Loefgr. Grows in Brazilian tropical rainforests on tree branches. The dark green, cylindrical stems, 6 mm in diameter, start out erect, then branch and bend to form a bush. They are covered with grey or white hairs growing in the areoles. The flowers are white, fragrant, 2 cm across. Fruits are red berries about 12 mm across.
		Tillandsia usneoides (L.) L.  This species of Tillandsia resembles the lichen Usnea in appearance and this is reflected in the species epithet. However, it is one of the hooded plant species which has stems, 1-6 cm long leaves, blue flowers, and dry fruits.  Only it does not grow roots. In American tropical and subtropical rainforests, dense, beard-like thickets of 6 m long hang from the branches of trees.  Water and minerals are taken up by scales attached to the leaves, giving the plants their gray color.