The name of the genus is derived from the Greek words phragma, which means "division", in reference to the unique three-chambered ovary (trilocular) and pedium, which means "slipper" - referring to the shape of the pouch-like lip petal. Some 24 species of Phragmipedium are distributed from southern Mexico, through Central America and down the spine of the Andes to Bolivia. They also occur eastward from Colombia into Venezuela and the Guianas, with one species only native to Brazil. Phragmipediums often grow in the splash zones of waterfalls or on rock cliffs where moisture is readily available. Some are found as terrestrials on roadsides or in pastures, with several living on the trunks of trees in wet, montane tropical forests.
Phragmipedium plants are known as the New World slipper orchids for their distribution across parts of Mexico, Central and South America, and the deeply pouched slipper-like lip of their flowers. Plants develop tall inflorescences arising from leaf bases, each bearing several flowers. The unique characteristics of the Phragmipedium flowers are their trilocular ovary and shield-like staminode.
The Phragmipedium genus itself is divided into five sections based on their floral characteristics and three of these sections are widely seen in the ongoing Orchids of Machu Picchu display.
1. Micropetalum – small flowers that are quite pubescent (hairy), wide petals, flowers open sequentially. An example is the Peruvian species- Phragmipedium besseae.
2. Phragmipedium – a “moustache” composed of two long, thin twisting petals more than four times the length of the labellum or “lip” petal), sheaths below floral bracts are generally absent, and flowers open all at once. An example is Phragmipedium caudatum.
3. Schluckebieria – large flowers, dominant petals that are much larger than sepals and almost round, flowers that open sequentially. Phragmipedium kovachii is the only member of this section.
So how does the Phragmipedium New World slipper orchid genus differ from the Paphiopedilum Asian slipper orchids? Floral characteristics are the primary visual indicators used to generally distinguish Phragmipedium from Paphiopedilum.
1. The terminal inflorescence is often branched in Phragmipedium and unbranched in Paphiopedilum.
2. All Phragmipediums have an infolded lip and a claw face. The claw face is the area of the labellum (pouch) that forms the tube between the opening of the pouch and the escape hatch for pollinators at the back, close to the stigma and pollinia. Most Paphiopedilum species, apart from those like Paphiopedilum micranthum, do not have an infolded lip.
3. All species of Phragmipediums have inflorescences with multiple flowers that either open simultaneously or sequentially, depending on the species. In contrast, inflorescences of Paphiopedilum species are either single-flowered or multi-flowered.
4. Phragmipedium leaves are generally longer and narrower than those of Paphiopedilum, which are shorter and rounder.
Like in most orchids, Phragmipedium has developed special anatomy to attract their pollinators in the wild, namely trap flowers that capture bees and flies and force them to carry their pollen in the form of pollinia by providing them with only one exit by passing through the plant’s reproductive parts. Pollinators, primarily gravid female hoverflies are attracted to the spots on the orchid’s lip that resemble aphid colonies in which they lay their eggs. The flies slip on the in-rolled lip, plummeting into the pouch from which the waxy interior walls and cupped shape prevent easy escape. The pollinator must climb up a stripe of bristles that act as a ladder, up the back of the pouch. The lip's lateral lobes partly block the exit, forcing them to ascend through a tiny opening beneath the column. There, the pollinator touches the orchid’s pollinia, which sticks to its back and finally escapes to carrying the pollinia on its back to another flower.
Visual cues attract pollinators to the flowers as well. Bee eyes are sensitive to shapes with a lot of edge, like the thin, twisting petals of Phragmipedium. In some species or hybrids of Phragmipedium, scent glands on the petal tips also provide olfactory enticement.
The unique forms and colours of slipper orchids not only attract insect pollinators, but also captivated uniquely extreme human collectors, who traditionally have been collecting brightly coloured Asian species, but whose attention has more recently turned to Phragmipediums as well. Their irrepressible, if not irresponsible passion and devotion to accumulating as many rare and unique species as possible, regardless of the welfare of wild populations, has propelled all slipper orchids onto the international endangered species list and restricted their trade via the Convention on International Trade in Endangered Species (CITES).
Currently, these species are used for breeding efforts worldwide resulting in long-lasting, robust, Phragmipedium hybrids which are now available on the horticultural market in myriads of colours, shapes, and sizes. Spot some of these beautiful Phragmipedium species and hybrids in our Orchids of Machu Picchu display!
Written by: Ziana Yacob, Manager (Research and Horticulture)
Ziana's fascination with the many wonders of plants led her to study Horticulture. She has been involved in propagating plants and nurturing our in-house orchid collections. Keeping plants alive is a challenge and she's constantly learning about what she should or shouldn't be doing!