Orchids in nature are almost cosmopolitan, although they are mostly represented in the tropical or sub-tropical areas of Asia, Central America and South America; only 15% of them grow spontaneously in temperate and cold areas. Most tropical species grow on tree trunks or on rocks, meaning that they have aerial roots capable of absorbing the necessary substances for their survival.
The family is represented by over 20,000 species, belonging to about 800 genera, of which 100 are present in Italy. The collection of the Botanical Garden occupies an area of about 25 m2, mainly located between the deciduous forest area in which it is partly included, and the adjacent grassy escarpment with travertine outcrop on the edge of the Palm collection. It consists of 23 species, belonging to 8 genera, and it was created in collaboration with the Germplasm Bank of Tuscia and the “Southern Etruria” section of the GIROS association (Italian Group for Research on Spontaneous Orchids).
The different ecological conditions of the area have allowed the cultivation of both species that favour shady environments, such as Dactylorhiza maculata (L.) Soó, Cephalanthera longifolia (L.) Fritsch, Platanthera chlorantha (Custer) Rchb., Orchis mascula L. and Orchis purpurea Huds., and species related to the grasslands on calcareous soils such as Anacamptis pyramidalis (L.) Rich., A. papilionacea (L.) R.M. Bateman, Pridgeon & M.W. Chase, A. morio (L.) R.M. Bateman, Pridgeon & M.W. Chasee and several species of Orchis L., Serapias L. and Ophrys L..
Some species are naturally present inside the garden, such as Ophrys sphegodes Miller subsp. passionis (Sennen) Sanz & Nuet, which is particularly abundant, O. bertolonii Moretti subsp. bertolonii and their spontaneous hybrid O. × grottagliensis P. & C. Delforge, growing near the entrance. Finally, a specific humid cultivation environment was set up for the growth of some Anacamptis palustris (Jacq.) R.M. Bateman, Pridgeon & M.W. Chase specimens, which is seriously threatened in Lazio, and of A. laxiflora (Lam.) R.M.Bateman, Pridgeon & M.W.Chase.
Finally, specimens of exotic species are present in the tropical greenhouse, such as the epiphytes Angraecum longicalcar (Bosser) Senghas and some hybrids of Phalaenopsis Blume.
