The Orchid Primer

Orchids belong to a very large family, the Orchidaceae, which includes between 15,000 and 20,000 species and over 100,000 hybrids: one of the largest plant families.

Contrary to popular belief, most orchids have small flowers and are often modest in color. By cross-breeding, hobbyists have succeeded in developing several lines with large, colorful flowers, but you’ll also discover orchids with flowers smaller than the nail on your little finger…

Another surprising fact is that not all orchids are tropical plants originating in faraway lands – they even exist in colder countries. In Quebec, for example, we have dozens of species.

Special Shape

If it’s not the size or color of the flower or its tropical exoticism that defines the orchid, how do the members of this vast family stand out? It’s the shape of the flower. Large or small, colorful or open, orchid flowers almost all share common characteristics that set them apart from any other plant.

First, orchids have three outer sepals and three middle petals. When the sepals of a flower resemble the petals, we speak of tepals: we can therefore say that orchids have six tepals.

So far, nothing unusual. But in the orchid, one of the tepals has changed. Rather than resembling the others, one of the tepals – usually the lower one – has developed and often takes on a different shape and color. This is the labellum.

Labellum

The labellum is unique to orchids. It serves a triple purpose: its shape and often its color attract the pollinating insects on which the orchid depends for fertilization. It also serves as an insect landing strip. Finally, once the insect lands on the labellum, it discovers markings that direct it to the nectar, so the labellum is also a kind of signpost.

But other flowers also have organs similar to the labellum. The real difference between orchids and the rest of the plant world lies in the center of the flower. In orchids, the male and female sexual organs are not separate. Instead, they are united in a single structure: the column (gynostem, if you’re a stickler). And pollen is not scattered copiously, in powder form, as in most other flowers, but gathered together in a mass called a pollinia.

Fertilisation

In orchids, everything is done to ensure successful cross-fertilization. When the insect enters the flower in search of nectar, it has no choice: the passage is narrow, it has to brush against the wall and the pollinia sticks to its body as it passes. As the insect leaves the flower, it takes the pollinia with it. When it flies to another plant of the same species and infiltrates the flower, the column, unique in shape for each species, first catches the pollinia before letting it in. In fact, the shape of the pollinia matches up precisely with the column of the other flower of the same species like a key in a lock: no other orchid species can carry out the pollination.

Curiously, once fertilization is assured, the sepals begin to wither. Within 24 hours, the orchid flower, which can often remain open for a month or more if not fertilized, wilts and begins an even more important task: it becomes a seed capsule, and it is these seeds that will ensure the plant’s succession.

Tiny Seeds

Another characteristic of orchids is their tiny seeds, finer than dust and only visible with a magnifying glass. Orchid seeds travel easily by air. But when they land, there’s a problem. Without a supply of food, the seed cannot germinate: it must come into contact with a fungus that will provide it with the nourishment it needs to germinate. The chances of an orchid seed finding exactly the right fungus in the conditions it needs to flourish must be around one in a million… but never fear, the tiny size of the seed means that each capsule can contain up to five million. So the orchid can multiply successfully.

Two Ways to Grow

Orchids have adopted two distinct ways of growing: they are either monopodial or sympodial.

Monopodials

Monopodial (single-stemmed) orchids produce a single stem that grows throughout the plant’s life. The stem can be very long, almost climbing, as in Vanda, or very compressed and almost invisible, as in Phalaenopsis. These orchids are placed in the middle of their pot and remain centred there. They cannot be divided. However, higher up the stem or on the flower stalk, they sometimes produce keikis, or babies, which can be separated.

Sympodials

From a short rhizome, sympodial orchids produce a series of stems called pseudobulbs, because they are often rounded and therefore bulb-shaped. Each pseudobulb normally flowers only once, but produces other pseudobulbs at its base, which in turn flower. So, after a few years, we see a whole family of pseudobulbs. A sympodial orchid, like Cattleya or Dendrobium, moves forward little by little, following its rhizome, just as a bearded iris does in the garden: even if you center it in its pot at first, it will eventually sway to one side or the other. As pseudobulbs multiply over time, sympodial orchids can be divided after a few years.

Epiphytes

Note that the majority of cultivated orchids are epiphytes, i.e. they grow not on the ground in nature, but on other vegetation, notably tree branches and trunks. To do this, they have had to develop unique roots that cling to rough surfaces and can easily capture the slightest drop of rainwater. However, these roots rot easily when surrounded by soil, as they require a high level of oxygenation. As a result, most orchids are not planted in potting soil, but in a much more aerated medium, generally composed of pieces of bark, sphagnum moss, polystyrene foam or other rather coarse particles. Many of the orchids you’ll see at shows will even be grown on a bark pad, just like in the wild.

Larry Hodgson published thousands of articles and 65 books over the course of his career, in both French and English. His son, Mathieu, has made it his mission to make his father’s writings accessible to the public. This text was originally published in Le Soleil on November 6, 2005.