The structure of the flora is based upon the systematic categories, which include the following groups of organisms of less or more closely relations: division, class, family, genus, species, subspecies and forma. This sounds good organised and easy to handle. In reality, the differentiation of the relationships between the different categories and the different species sometimes is difficult. Please look at the chapter "hybrids".

Long times ago, the plant family of the orchids splits up into three main categories. Each of them took their own way during evolution. Theses tree main categories different by the number of stamens per flower. The botanists don't agree, if these categories are subfamilies of one single family or three different families. The tree main categories are:

• The tropical Apostasiaceae, which have three stamens per flower. World-wide two genus and 15 species are known.
• The Cypripediaceae with two stamens each flower, four genus and about 100 species.
• The Orchidaceae with only one stamen per flower. With about 730 genus and more than 20.000 species most of the orchids of the world belongs to this category.

In Europe only two of the three main categories can be found. First the Cypripediaceae with the one and only genus Cypripedium (lady slipper) and three different species. 35 genus and all the other European orchid species belongs to the main category of the Orchidaceae.

The following pictures show the different genus considered at orchis.de. Looking at the pictures you can see how different orchid flowers are. And yet all of them belong to the same family. The sequence of the pictures follows the system of orchids seen below.

Main group Cypripediaceae
Cypripedium
Cypripedium calceolus
Main group Orchidaceae
Sub-family Neottioideae
Cephalanthera	Epipactis	Goodyera	Limodorum
Cephalanthera rubra	Epipactis helleborine	Goodyera repens	Limodorum abortivum
Listera	Neottia	Spiranthes
Listera ovata	Neottia nidus-avis	Spiranthes spiralis
Sub-family Orchidoideae
Aceras	Anacamptis	Barlia	Chamorchis
Aceras anthropophorum	Anacamptis pyramidalis	Barlia robertiana	Chamorchis alpina
Coeloglossum	Comperia	Dactylorhiza	Gennaria
Coeloglossum viride	Comperia comperiana	Dactylorhiza insularis	Gennaria diphylla
Gymnadenia	Habenaria	Herminium	Himantoglossum
Gymnadenia conopsea	Habenaria tridactylites	Herminium monorchis	Himantoglossum hircinum
Leucorchis	Neotinea	Neottianthe	Nigritella
		no photo
Leucorchis albida	Neotinea maculata	no example	Nigritella corneliana
Ophrys	Orchis	Platanthera	Serapias
Ophrys cilicica	Orchis ovalis	Platanthera chlorantha	Serapias vomeracea
Steveniella	Traunsteinera
no photo
no example	Traunsteinera globosa
Sub-family Epidendroideae
Calypso	Epipogium	Hammarbya	Liparis
Calypso bulbosa	Epipogium aphyllum	Hammarbia paludosa	Liparis loeselii
Malaxis
Malaxis monophyllos
Sub-family Vandoideae
Corallorrhiza
Corallorrhiza trifida