What are orchids? Characteristics and significance

In Mexico, as in many countries, there is a widespread idea that orchids are plants with magnificent flowers, of invariable shape and restricted colors, which is far from corresponding to the characteristics of these plants. This has determined their ignorance as an important element of the flora of the country.

The approximate number of 25,000 species worldwide makes it possible to contemplate a seemingly endless series of sizes, colorations, and strange shapes. In addition to constituting, in many cases, an ornament of economic importance, other values of their possible practical application are now beginning to be glimpsed.

Orchids are the most numerous family of plants, only comparable in number with the plants of a different family, that of the composites. With such a large number of individuals, with a wide distribution, it is understandable that they show a variety of equivalent adaptations and are found not only in warm regions but also in temperate and cold regions, inhabiting ecosystems and regions of very different orography.

The colorations of orchids cover the whole range, except black. The presence of some spots or floral segments of intense purple color in some species has extended the idea of the existence of "black" orchids. Two such species are Encycha cochleata from Tropical America and Coelogyne pandurata from Borneo.

Uses of orchids

There are references to the use of orchids in China since before Christ. However, the evolution of the exploitation of these plants from a hobby to commercial production was very slow. It was not until 1821 that commercial cultivation began in greenhouses near London. By 1913, the Sun Kee greenhouse was opened in Singapore to produce orchids for cut flower sales and is still in production.

Currently, in the United States, England, France, Japan, China, Thailand, Australia, Hawaii, and Singapore there is greater interest in the cultivation and exploitation of orchids. Mexico can and should take part in this branch of floriculture, protecting, propagating, hybridizing, and exporting Mexican orchids, because of the great diversity in the country, where more than a thousand species have been reported, most of which coexist in tropical climate regions.

Traditionally orchids have been used by various peoples for ornamental and medicinal purposes. The Chinese were the first to cultivate them since approximately 500 B.C. Later, in the 5th century, the Greeks increased their medicinal use. The name orchid derives from the Greek word orchis, applied to the testicular aspect of the tubers.

In America, it was the Aztecs who mutilated the medicinal, aromatic, edible, artisanal, and ornamental use of these plants. One of them, known worldwide, is the tlilxóchitl or vanilla (Vanilla plamfolia) that was taken to Europe and from there to tropical regions such as the island of Madagascar, which has become the first producer in the world.

The first orchids arrived in Europe from the New World in 1731. Since that time, the cultivation and propagation of the specimens was faced as a challenge that contains interesting historical situations.

Distinguishing characteristics of orchids

To become familiar with these plants it is necessary to know their morphological characteristics, which are important for collecting and crossbreeding them. There are certain characteristics that separate orchids from all other flowers.

Zygomorphic flowers. They can be cut only in one plane and will divide into two equal halves, if cut in any other plane, they result in two different parts.

Sex organs are united in a single waxy structure (column or gynandrous). If the front part of this is pulled, a sheath containing pollen (the shiny surface of the pollen column) is detached.

Pollen grouped in sacs of 2 to 8, depending on the species, is called a polymath. Primitive orchids do not have pollinia and the pollen is loose. The pollinia are joined at the top by a sticky substance.

Rostellum. It is the dividing area between anthers and pistil, which prevents self-pollination; in addition, it disperses a viscous substance on the back of any insect in contact with it.

Seeds. The number of seeds in a capsule (fruit) varies from thousands to millions. They have no reserve substance or storage tissues.

Habitats of orchids

Orchids are distributed from Alaska to the tropics; in the tropics, they are commonly found on native trees, preferably deciduous. According to where they grow, orchids are classified as follows:

Terrestrial.

Epiphytes (non-parasitic). They use the tree as a support for growth; most tropical orchids fall into this category.

Lithophytes. They grow on rocks.

Orchids are monocotyledonous, herbaceous, perennial or annual, terrestrial, epiphytic, rupicolous, saprophytic, or even semi-aquatic plants. Commonly, epiphytes, from warm and temperate regions, group the showiest ones. As a result of this adaptation (which is why they can often be found several tens of meters above the ground), they have developed a widening of the stem - called pseudobulb - with the capacity to store water, and aerial roots provided with an outer layer of dead cells that allow the absorption of water and establish an access route for fungal filaments that provide the plant with food substances.

Types of orchid growth

Monopodial - A single erect stem, with axillary flowers. Roots appear increasingly upward (vane-like).

Sympodial - horizontal rhizome, with vertical growths (pseudobulbs) and flowering at the terminal apex or on the sides. New roots appear at the front and expand horizontally. Therefore, this type of plant should be placed in the margins of the pots, to use 100% of them.

Propagation of orchids

There are two methods for orchid propagation: macro propagation and micropropagation.

Macro propagation includes a number of traditional methods for multiplying plants, such as stem and flower scape cuttings, division of mother plants, and aerial hypotrophy. These methods are slow and ineffective for commercial propagation.

Plant division. It is done with plants of sympodial growth, which have six or more pseudobulbs, cutting the rhizome between the third and fourth pseudobulb, and planting both plants in individual pots, taking care that the youngest part is oriented towards the center of the container and the oldest part towards the edges, as well as the division after flowering. Most plants are divided every three years.

Vegetative cuttings. This method is successfully practiced with monopodial growing species. Cuttings are usually 75 cm (2 ft) long, with up to twelve leaves and few aerial roots, which are planted in pots.

Micropropagation. This method can be divided into two groups, based on the objective of the work and the explant. The first group is sexual micropropagation (seed germination) and the second corresponds to asexual propagation by tissue culture.

Economic importance of orchids

At present, orchids are an important commercial item in two main lines. One is the export of cut flowers from cultivated native plants, which is a good source of foreign exchange in countries such as Venezuela, Colombia, and Thailand. The other is the sale of cultivated plants of different sizes, including flowering.