costa rica orchids plants botantical gardens

costa rica orchids plants botantical gardensl
In the amusing words of one British biologist, "As we delight in the strange and exotic beauty of orchid flowers it is salutary to reflect, that we are, in essence looking at their genitalia."

Humor aside, in most people the word orchid conjures up images of extravagant, multihued, exotic blossoms. In some cases this is actually the case and reality does one better than our own imaginations. However orchid flowers are so numerous that many might go unnoticed even if they were right in front of us. The orchids belong to one of the largest plant families in the world. There are approximately 25,000 species of orchids in the wild and close to another 25,000 varieties of hybrids that have been catalogued. The actual blossoms can range in size from one millimeter (Platystele sp.) to twenty five centimeters across. If one were to include the pendant petals of a species known as Phragmipedium, it would measure about half a meter, or one and a half feet in total length. Orchids occur throughout the globe, with the exception of Antarctica, and have been encountered at elevations of 14,000 feet. These plants have evolved an array of different lifestyles-from terrestrial to epiphytic (canopy dwellers) to saprophytic (non-photosynthetic, consuming organic nutrients in the substrate).

The attempt to become an orchid expert is a formidable challenge. Although the scientific name of the family, Orchidaceae, is rather easy to recollect; the family is so huge that taxonomists unfortunately have had to break down the classification even further into subfamilies such as Epidendriodeae, tribes (Maxillareae), and subtribes (Maxillariinae). To make matters worse, wild orchids have a rather strong inclination to hybridize. Scientists suggest that the family is genetically in a fluid state. Evolutionarily speaking, this is considered to be a very young plant group, just recently formed. At this stage in their evolution the boundaries between species don't seem to have solidified and genes seem to flow between species with startling ease. This means that individual plants within the same species might show considerable variation in their appearance.

With a little practice the three sepal/ three petal arrangement becomes more easy to recognize. The lip or labellum is particularly noticeable on the larger specimens. In Costa Rica about 88% of the family is epiphytic which means many of them have special adaptations for life in the canopy. Water storage mechanisms such as fleshy leaves and pseudobulbs (a thickened stem) make many orchids stand out among fellow epiphytes.

Once you have delved into the world of orchids for a while you eventually come to appreciate the more intriguing aspects of their ecology. One unexpected relationship that has been established is a symbiosis between orchid roots and fungi. To this date not a single species of orchid is known to grow in the wild without the benefit of this mycorrhiza, as this symbiosis is called. The fungus is particularly critical for germination, when the tiny seed of the orchid has virtually no food source of its own. At this stage the fungus provides nourishment for the growing plantlet Generally, in nature, one genus of orchid occurs with one genus of fungus.

Orchid pollination occurs through the action of five main classes of organisms: bees, flies, moths, butterflies, and birds. Although the reward for pollinators tends to be nectar, there are other lures by which the orchids attract these organisms. Certain bees feed an orchid produced oil to their larvae while others actually harvest an unusual form of pollen called pseudopollen. Male euglossine bees, which are a brilliant metallic green, visit orchids that provide them with a type of perfume that they store in special organs on their hind legs. In contrast to this sweet scent, other orchids emanate a foul odor that is reminiscent of rotting meat in order to attract carrion flies. Some orchids offer nothing at all and simply try to trick insects into visiting them by exhibiting vivid colors. One of the most elaborate attractants has evolved in an orchid found in Europe known as the bee orchid. This species has flower parts that resemble a female bee which serves to lure in male bees that would like to copulate with the impostor. In truth many of the pollinators of orchids are still not known. This huge plant family still holds back many secrets that are to be unraveled by amateur and specialist alike.

Most researchers believe the family began evolving primarily as terrestrial plants. However, over the eons the vast majority of species have become adapted to life in the canopy. A few of the major arguments explaining why this might have occurred point out the benefits of an epiphytic existence. First of all comes the theory of niche ecology. This essentially states that when a new organism comes into an ecosystem it must compete with preexisting species (to the point where one or the other is displaced or eradicated) or find a vacancy within the system that has not been fully exploited. What this has meant for orchids is that they had less competition in the upper tiers of the forest than on the ground. This realm also receives more sunlight than the forest floor, and is not as susceptible to being waterlogged or leached by heavy rains. This adaptation to life in the canopy has become so vital to the great majority of orchids that most species that fall to the ground perish. The most significant drawback to life as an epiphyte is the greater potential for desiccation when exposed to sun and dry winds.

Albeit the greatest diversity of orchids is to be found in Colombia and Ecuador, Costa Rica possesses a formidable 1200 species (data from 1993). Its misty cloud forests are particularly ideal habitats for the many epiphytic species. To a great extent the flowers are not as big and gaudy as the ones that are produced commercially, but display an amazing diversity of form, color, and shape. The nation's national flower, the Guaria Morada (Cattleya skinneri) is bold, large and violet, and also happens to be an orchid. Two of the best locations to indulge in orchids are Lankaster Gardens, on the outskirts of Cartago, and the Orchid Project, found in Monteverde.

Written by Marc Egger