The seeds are generally almost microscopic and very numerous, in some species over a million per capsule. After ripening, they blow off like dust particles or spores. They lack endosperm and must enter symbiotic relationships with various mycorrhizal basidiomyceteous fungi that provide them the necessary nutrients to germinate, so all orchid species are mycoheterotrophic during germination and reliant upon fungi to complete their lifecycles.
Using the molecular clock method, it was possible to determine the age of the major branches of the orchid family. This also confirmed that the subfamily Vanilloideae is a branch at the basal dichotomy of the monandrous orchids, and must have evolved very early in the evolution of the family. Since this subfamily occurs worldwide in tropical and subtropical regions, from tropical America to tropical Asia, New Guinea and West Africa, and the continents began to split about 100 million years ago, significant biotic exchange must have occurred after this split (since the age of Vanilla is estimated at 60 to 70 million years).
The goal is to get each mix particle to absorb as much water as possible. To give the potting mix enough time to absorb water, place the entire pot in a bowl of water for 10 to 15 minutes, then lift it out and let the excess water drain before putting the pot back in place. This technique works well for orchids potted in clay. Since clay is porous, water penetrates the walls of the pot and is absorbed by the bark.
Horticultural techniques have been devised for germinating orchid seeds on an artificial nutrient medium, eliminating the requirement of the fungus for germination and greatly aiding the propagation of ornamental orchids. The usual medium for the sowing of orchids in artificial conditions is agar agar gel combined with a carbohydrate energy source. The carbohydrate source can be combinations of discrete sugars or can be derived from other sources such as banana, pineapple, peach, or even tomato puree or coconut water. After the preparation of the agar agar medium, it is poured into test tubes or jars which are then autoclaved (or cooked in a pressure cooker) to sterilize the medium. After cooking, the medium begins to gel as it cools.
Cymbidium carry tall stems with many flowers that have a more typical orchid shape. They are easily identified by their grassy leaves, and they readily form large clumps. Most common are the cool-flowering types, which need to experience a cooler winter (nights in the 40s for some time in the fall) in order to initiate flowering. Once the flowers open, they can last for up to two months or more, especially in a cool environment. These are very showy and rewarding plants, and a plant in a six-inch pot can carry three stems with 15 or more flowers each, depending on the type.