GENERAL KNOWLEDGE

INTRODUCTION

Orchids form one of the largest families in the plant kingdom with more than 35,000 botanical species distributed in all latitudes, except for the desert regions and the poles. Their size varies from five millimeters to five meters. Most of cultivated orchids come from the tropics and subtropics around the globe.

GROWING MODES

The monopodial mode does not have a rhizome and is recognized by its vertical and indeterminate growth. The stem has a strong apical dominance which means that the flower spikes will appear in the axils of the leaves and not at the end of the terminal shoot. Some plants of the genus Vanda and others in this group will also produce aerial roots on their long stems allowing stem "cuttings". Otherwise, for the others (Phalaenopsis et cie) which produce little or no suckers, sowing and cloning in the laboratory will be the options to multiply them.

The sympodial mode is recognized by its growth from a horizontal rhizome from which shoots with determined growth, with or without pseudobulbs, emerge. The flower spikes will emerge from the end of these shoots or at the base of them (Cymbidium, Paphiopedilum, etc.) and which will form, over time, a growth in tiller. The plant can then be divided by severing the rhizome to obtain a division of at least 3 pseudobulbs to ensure good recovery.

PSEUDOBULB

In many sympodials there is a swelling at the base of the stem called pseudobulb, which serves as a reservoir by accumulating water and food in anticipation of periods of rest. The shape of pseudobulbs can vary according to genera and species, from ovoid to elongated.

EPIPHYTIC PLANTS

Most of orchids are epiphytic (grow on branches and trunks), lithophytic (on rocks) or terrestrial and semi-terrestrial (peat bogs) They are not parasitic plants: their roots have adapted to attach themselves to branches and trunks, in the case of epiphytes, according to their need for light in their natural environment in order to use the available resources optimally.

FLOWERING

Most orchid species flower once a year, with flowers that can vary in longevity between species and hybrids. The onset of flowering is linked to one or more combined factors (light intensity, temperature as well as the photoperiod).

Flowers use the most ingenious means to lure pollinators, by imitation, chemical or visual seduction, or by provocation. The flowers of the orchid are composed of three sepals and three petals, one of which is modified into a lip. This is often curled and colored to attract pollinators to the stamens and pistil, which are fused into an organ called a column. It is this structure that characterizes orchids.