Paphiopedilum, often called the Venus slipper, is a genus of the Lady slipper orchid subfamily Cypripedioideae of the flowering plant family Orchidaceae. The genus comprises some 80 accepted taxa including several natural hybrids. The genus is native to Southeast Asia, the Indian Subcontinent, southern China, New Guinea and the Solomon and Bismarck Islands.
The species and their hybrids are extensively cultivated, and are known as either paphiopedilums, or by the abbreviationpaphs in horticulture.
The type species of this genus is Paphiopedilum insigne.
Paphiopedilum species naturally occur among humus layers as terrestrials on the forest floor, while a few are true epiphytes and some are lithophytes. Thesesympodial orchids lack pseudobulbs. Instead, they grow robust shoots, each with several leaves; some are hemicryptophytes. The leaves can be short and rounded or long and narrow, and typically have a mottled pattern. When older shoots die, newer ones take over. Each new shoot only blooms once when it is fully grown, producing a raceme between the fleshy, succulent leaves. The roots are thick and fleshy. Potted plants form a tight lump of roots that, when untangled, can be up to 1 m long.
Members of this genus are considered highly collectible by orchid fanciers due to the curious and unusual form of their flowers. Along with Cypripedium, Mexipedium,Phragmipedium and Selenipedium, the genus is a member of the subfamilyCypripedioideae, commonly referred to as the "lady's-slippers" or "slipper orchids" due to the unusual shape of the pouch-like labellum of the flower. The pouch traps insects seeking nectar, and to leave again they have to climb up past thestaminode, behind which they collect or deposit pollinia. The orchid, despite several attempts to clone by tissue culture, has never been successfully cloned, for unknown reasons. This means every plant is unique.
Members of this genus have unusual stomata. Whereas most land plants' stomata have guard cells with chloroplasts in theircytoplasm (including those of closely related Phragmipedium slipper orchids), Paphiopedilum stomata do not. This difference results in simpler, but weaker control of stomatal function. For example, most plants close their stomata in response to either blue or red light, but Paphiopedilum guard cells only respond to blue light. The fact that they lack chloroplasts has made them valuable to researchers investigating stomatal function. For example, it enabled the discovery of intracellular events that precede stomatal closure.
The paphiopedilums are among the most widely cultivated and hybridized of orchid genera. Spectacular new species are being discovered every now and then; for example the Golden Slipper Orchid (P. armeniacum), discovered in 1979 and described in 1982, amazed growers of orchids by the extraordinary beauty of its golden flowers. In addition, growers have bred thousands of interspecific hybrids and registered them with the Royal Horticultural Society in London over the years.
These orchids are relatively easy to grow indoors, as long as conditions that mimic their natural habitats are created. Most species thrive in moderate to high humidity (50-70%), moderate temperatures ranging from 13 to 35 degrees Celsius and low light of 12,000 to 20,000 lux. Modern hybrids are typically easier to grow in artificial conditions than their parent species