Orchid Habitat

Orchids are herbaceous plants, perennial (rarely annual), terrestrial or epiphytic, sometimes climbing, and sometimes saprophytic or, rarely, mycoparasitic. With respect to epiphytic orchids, they are said to become eternal. In fact, in nature, their survival is tied to the tree of life that sustains them. Collected plants known to be from the mid-nineteenth century are still growing and flourishing in many collections.

The stems are rhizomes or corms in terrestrial species. In the epiphytic species, however, stems are thickened at the base forming pseudobulbs that can store water and nutrients and, in general, are covered by membranous leaf sheaths that dry out with age.

There are two basic types of growth within the family: the sympodial type, which produces multiple stems; and the monopodial type, which produces a single stem. The sympodial type of growth is more common within the family.

Most of these orchids have pseudobulbs which function as reservoirs for water and nutrients. The plant holds the pseudobulbs almost vertically, and growth and further development of new shoots occurs horizontally between the pre-existing pseudobulbs.

Each new pseudobulb originates on the basis of a past pseudobulb and, with its growth, causes new leaves and roots. The leaves originated in each pseudobulb can last many years, providing nutrients for the entire plant until they turn brown and die.

Even without leaves, each continues to maintain pseudobulb growth and supply the energy required for growth and flowering in the rest of the plant. Examples of this type of orchid growth are the genera Cattleya, Dendrobium and Oncidium.

With monopodial growth, unlike sympodial, the orchid shows a single main stem that grows upright and indefinitely from the center of the plant. Normally, the stem grows upward and roots originate at the nodes, which grow downward. The plant, as it grows, loses its lower leaves as new leaves are formed at the upper end. Some species of orchids with such growth are those belonging to the genera Ascocentrum, Phalaenopsis and Vanda.