Thursday, July 5, 2007
Orchids: Classification [ Monopodial & Sympodial]
All orchids belong to the Orchid Family, Orchidaceae (or-Kid-ACE-ee-ee). Orchids are divided into two basic growth types :
 Monopodial and
I. Monopodial [Latin for single foot] ...
In this type of growth pattern there is one main stem which grows indefinitely from the center of the plant. Normally, the stem grows straight up and aerial roots sprout from where the stem and leaves meet. The plant will lose its leaves from the ground up, continually growing new leaves from the tip and making new roots along the stem.
Examples of monopodial orchids are Phalaenopsis, Vanda and Angraecum.
Inflorescences rise from the stem at the base in the case of Phalaenopsis or from between leaves in the case of Vanda.
II. Sympodial [Latin for many footed] ... This growth type is more common among orchids. Sympodial orchids, possess a rhizome which sends out a shoot. This develops into a stem and leaves and eventually produces flowers. In time, from the base of this growth, a new shoot develops and so on in a continuous cycle. The buds are often, though not always, protected by a sheath.
The mid section of stems of sympodial orchids are often expanded into water-storage organs called pseudobulbs . These vary greatly in size and shape, ranging from tall and pencil-thin to bulbous and onion-like. The pseudobulbs function as storage reservoirs for food and water. They function very much like rhizomes on terrestrial plants. Many times more than one growth at a time will be present. The growth begins at the base of the pseudobulb and is called a “lead.” Both the shoot and roots will grow from this lead. Leaves can last for several years and provide nourishment to the plant until they turn brown and die. Even without a leaf, the pseudobulb will continue to support the plant.
Examples of sympodial orchids are Cattleya, Cymbidium, Dendrobium, Miltonia, Odontoglossum, Oncidium, and Paphiopedilum ...