The Flowers of orchids

The Flowers of orchids
‘The flowers of orchids, however highly modified, are all built on a common plan, with 3 sepals, 3 petals, one of which is highly modified as the lip, 1 or 2 stamens borne on a complex structure, the column which consist of the stamens united to the styles and stigmas of the inferior, 3-carpellary ovary.

Though this plan is generally easy to see, the variations on it are very numerous, and include such featuring as fusion of various parts (especially of the sepals), the occurrence of spurs (sometime formed by the uppermost sepal, on other occasions by the base of the lip), and great variations in the relative sizes of the various parts.

In all the keys and descriptions the flowers are considered to be resupinate unless the contrary is stated.

In species is hanging or arching inflorescences the degree of resupination of the flower may vary, those flowers towards the hanging apex being non resupinate , while those at the more erects base may be properly resupinate.

However, in some genera with hanging inflorescene, the flowers are all strictly resupinate.
The Flowers of orchids