Although it is the largest flowering plant family, the group as awhole show less vegetative and floral diversity than many smaller families. There are, however several characteristics that distinguish orchids. Their seeds are minute and dustlike and are produced inside, in a capsule.
The seeds may take up to 18 months to germinate and a further 18 months to mature into flowering plants. Unlike other seeds they have no endosperm (part of the seed where food is stored) and therefore depend on an external food source for nutrients throughout germination. For successful growth in the wild orchid plants almost always maintain a symbiotic relationship with various species of fungi.
This is a relationship of mutual benefit to the species concerned-the fungi providing nutrients during germination and until the orchi is established, and the fungi benefiting from sugars from the orchid when it is able to photosynthesize.