The seeds are extremely small and very numerous, in some species over a million per capsule. After ripening, they blow off like dust particles or spores. They lack the food reserve called endosperm, so must have symbiosis with fungi to get nutrients to germinate. All orchid species rely on fungi to complete their lifecycles. As the chance for a seed to meet a fitting fungus is very small, only a minute fraction of all the seeds released grow into adult plants.