Orchids Paphiopedilum callosum
It has already been reported, that the orchid flower is in the same way as the tulip, Märzenbecher and Krokus has a six-fold flower envelope. At Venus- and we only ever discover lady's slipper species 5 Petals. The numerical reduction is due to the fused together of two Sepala (outer bracts) to a uniform leaf organ (synsepalum), which in our illustration of Paphiopedilum callosum lies directly behind the labellum and therefore remains hidden from our eyes.
The most noticeable section of the flower is the lip, which looks like a delicate shoe or slipper (Paphia is a nickname for Venus, pedilon griech. means shoe, Venus shoe). Within this family group, however, the labellum is not just an exposed organ, but it also functions as an insect trap at the same time. The winged flower visitor gets into the "shoe" without difficulty, but then can no longer climb its elevated walls. After some back and forth, the insect that desires to exit crawls up the “sole of the shoe” to the “heel area” and can exit the dungeon through two extremely small openings. These little holes are flanked by a stamen each (the Cypripedioideae still possess 2 Stamens!) and from sections of the scar, so that the insect inevitably smears itself with pollen when it is forced through, which it dumps on the stigma at one of the next blossoms. There is an interesting technical term for this extremely sensible and highly specialized pollination facility: Kettle trap flower.
Even if we mentioned earlier that there was only a five-leaved cypripedioid flower envelope, here, too, exceptions confirm the rule: in the Pacific-North American common Cypripedium arietinum, the two lateral sepals are not fused to form a synsepalum.