Orchids are beautiful and fascinating flowers that have long held a grip on the human imagination; many theorize that this is perhaps due to their sexual appearance. Orchid lovers find that the bloom of an orchid plant is so gorgeous and distinctive that they can be referred to as living jewels. These amazing plants have adapted to almost every environment on earth, and this has led to a great diversity in orchids. There are between 25,000 to 30,000 different kinds of orchids throughout the world, and many species are still being discovered and cataloged. In addition there are also approximately 60,000 known types of orchid hybrids that have been created by orchid growers, thus making orchids the largest flowering plant family on earth.
Orchids are also widely considered to be the most highly evolved of all flowering plants. So you may want to ask: What makes a plant an orchid? Technically, an orchid is a flowering plant that exhibits a unique reproductive strategy. All orchids have both the male and female reproductive structures fused into a single structure that is commonly called a “column”. This tends to lay opposite of the lip. They also share some other floral characteristics. This may include (usually) a highly modified petal called a lip, or labellum. This can be thought of as a landing pad for bugs. These items are easy to identify in most of the common orchids, although some orchid flowers are so small (or different) that it can be difficult to tell. It is also important to note that even though the reproductive parts are contained in the same structure, orchids have evolved a highly efficient system of insuring that self pollination never takes place.
One of the fascinating characteristics of orchids is the fact that they are distinguished from other orders of flowering plants by a combination of floral characteristics rather than just by a single characteristic that would be unique just to them. Orchid flowers are borne on stalks called pedicels. During the growth and development of the flower, the pedicel rotates 180 degrees, so that the mature orchid flower is borne upside down. The orchid is made up of three sepals (floral whorls). Within the flower’s three sepals (outer whorls) and three petals (inner whorls), all the sepals and the two lateral petals are usually similar to one another in color and shape. The remaining petal is always distinct from the other ones and is called the labellum, or lip; since it is usually larger and different in color and shape, often being lobed or cupped. The labellum acts as a landing platform for the orchid pollinator, and it is theorized that it may attract the pollinator to the flower through particular color patterns and shapes to which the pollinator responds in particular ways.
Orchids also have only one stamen (male floral organ), and in most orchids it bears only one anther (pollen-producing structure); in a few orchids, there are two anthers that are produced. The pollen is not granular, as it is found in most flowering plants, but is brought together in a number of masses, or sacs, that can vary in texture from mealy to horny. There are also three stigmatic lobes (pollen-receptive areas) that are usually present and located near the anther, although usually only two are functional.
The ovary is below the other flower parts and is surrounded by pedicel (column) tissue. It is divided into several sections that each contains numerous ovules (egg-bearing structures) that mature into seeds. The seeds are small, with only a single undifferentiated embryo. As many as two million seeds can be produced from a single orchid seedpod. It is also interesting to note that unlike most other flowering plants; orchids have no food-storage tissue.
Orchids do not vary as much in what they need as they do in floral structure, but a great variety of forms exists, reflecting the wide range of habitats they occupy. About half of the orchid family is epiphytic, which means they grow on other plants for the support they provide, but some are parasitic and others live on decaying vegetation. A few Australian species even complete their life cycles entirely underground.