The earth-dwelling orchids are even more dependent than the epiphytes on the extent and density of the total vegetation. This already applies to our native orchids, whose location conditions are easily accessible to our degree program. In subtropical-tropical areas very few grow in the densely shaded subsoil of the forests. Their number increases under sparse trees and increases even more in savannah landscapes, which it e.g.. in Africa and Australia there. In our homeland we also find many species as inhabitants of meadows or slopes interspersed with bushes and sparse trees. The Asian Paphiopedilum are generally considered to be earth dwellers. However, they are only conditionally so, since rocks are often or exclusively populated, while other species prefer clay soil interspersed with deciduous humus and are less lime-loving. In South Africa we find, roughly equal to the species on the coasts of the Baltic Sea, Orchids growing in almost sterile sandy soil. The one in the south- and Central America, on the other hand, grow in periodically dry swamps in an area-wise massiveness like our reeds. The ability, to grow on rocks or on almost vertical rock walls, also have cattleya. This is what orchid hunters report, that Cattleya per-civalliana shows almost exclusively this growth form in its home country Venezuela; in the Himalayas it is Coelogyne cristata and in Eastern Australia it is Dendrobium speciosum.
In some orchids one can still find the transitions from soil-dwelling to epiphytic way of life. They begin their existence in the ground, climb up the trunks of the jungle trees, lose the connection downwards and continue to live epiphytically. This is the case with vanilla, of which genus certain species provide the aromatic fruits known as vanilla pods. Vanda teres and other monopodial orchids also develop in this way. Pronounced epiphytes are highly dependent on the density and extent of the total vegetation, which is essentially a regulator of light enjoyment for epiphytes. It is of course important, the height of the trees at which the plants grow; because upwards the strength of the light increases. Phalaenopsis love the shade; their soft fleshed ones, broad leaves do not tolerate strong sunlight. In their homeland they are found preferentially on the lower parts of the tree trunks of ever-moist low-lying forests. The counterpart to this are Vanda species in back India. Their leaves, which are often only furrowed or almost stalk-round, can withstand the strongest exposure to light. According to their shape, they are adjusted to skylight and find this on the gnarled oaks with light foliage that they inhabit. Within these two opposites mentioned, the epiphytic orchids of very different sizes and shapes grow. Often they live together with the abundance of other epiphytes, like Bromeliaceen, Araceen, Peperomien, Farnen u.a., which are subject to the same living conditions. Due to the close interweaving of their roots, they often form a unified whole and become clumps of considerable size, like it often does, is especially the case with small species. This finding is an indication of the maintenance of such species. They should remain undivided for years if possible. Then they can develop into beautiful pieces under other favorable conditions. The genus Pleurothallis is an example.
According to reports from orchid collectors, some species prefer certain trees. To what extent there is a bond or dependency here, is still unclear. Probable is the assumption, that certain properties of the tree species – such as the structure of the bark or the density of the foliage, possibly also possible excretions of the same – are decisive for a preferred settlement.