The Other Slipper

Our magnificent Phragmipedium caudatum would have attracted far more admirers were it not for the raspberry kovachii flowering simultaneously on the waterfall. The lucky visitors who managed to tear themselves away and explore the back of the High Elevation House found this beauty overlooking the Sun Pitchers (Heliamphora) and bromeliads.

The markings on the oversized drooping sepals of Phragmipedium caudatum remind me of fenestrations, the translucent 'windows' characteristic of the pitchers of Nepenthes aristolochiodes, Sarracenia psittacina, and the flowers of Bulbophyllum grandiflorum. Fenestrations are thin parts of the leaf or flower that allow light to be seen by an insect trapped in the interior, but aren't actual exits. In carnivorous plants, the insect flies into the 'windows' in the leaves over and over until it tires and slides into the liquid below. Fenestrations in a flower direct the pollinator toward the anther and stigma, but I don't know if the markings on Phragmipedium caudatum function in this way.

Phragmipedium caudatum grows on rocky seepage slopes at 1,500 to 2,000 meters elevation from southern Mexico to Peru. Our plant is embedded in live sphagnum on a large granite rock in the High Elevation House where it receives a 75º daytime maximum temperature and a 52º nighttime minimum. This week, it has three flowers open simultaneously.

There's Something About Slippers

Phragmipedium Don Wimber

The pollen masses (pollinia) are hidden behind the shield-shaped staminode in the center of the flower.

Phragmipedium Cape Sunset flowering at the Fuqua Orchid Center. The yellow pollinia are just barely visible over the top of the staminode.

How do you explain the appeal of slipper orchids? What is it about slippers that makes them irresistible?

I think it's the pouch, or toe cap, of the slipper that is the lure. Very few of our visitors can resist the urge to get closer and peer inside. What's inside that pouch? What's it for?

It's a trap, actually, for the insect that pollinates the slipper orchid. For an insect what's inside that pouch is a convoluted and probably exasperating journey in search of an exit. Once underneath the tightly inrolled lip the insect is forced behind the shield-shaped staminode where it collects or leaves behind the pollinia, and finally escapes. The pouch is a trap to ensure fertilization. No insectivory is involved.

If you love slippers you won't want to miss our spring Orchid Daze 2013 display opening February 9! Our display will feature slippers of all sizes, shapes and colors.

How to Grow Andean Slipper Orchids

Phragmipedium schlimii

Bright, moist and cool(ish) just about sums it up. That may sound like a strange combination for a tropical orchid, but it isn't really. Not for an orchid that grows along mountain springs near the Equator.

When I first started growing orchids I grew the Andean Phragmipediums (Phrags) right alongside the Asian tropical slippers, the Paphiopedilums. Same greenhouse, same treatment. They're both tropical slippers, right? Same requirements!

Wrong!

Picture the lovely Andean slippers growing on a steep granite embankment at 4,000 ft in the mountains of Peru. The rocks glisten with moisture from an underground seepage. Before noon the entire hillside is flooded with sunlight. In afternoon the area is bathed in mist.
Now picture Paphiopedilum stonei growing on the island of Borneo, wedged in the crevices of limestone cliffs and shaded by the crowns of trees growing at the base of the cliffs. The air is warm and humid and the microhabitat is drier and shadier.

No wonder my Phrags wouldn't flower!

Phragmipedium besseae

Cheat Sheet for Andean Slipper Orchids 

Phragmipedium schlimii and Phragmipedium besseae

PRONUNCIATION: frag-mih-PEA-dee-um...SHLIM-ee-eye....BESS-ee-ay
ORIGIN: Colombia, Peru, Ecuador
CLIMATE/ECOLOGY: As terrestrials on continuously wet embankments exposed to morning sun in lower montane (~2,000-6,000 ft) tropical forest.
GROWTH HABIT: Fan-shaped growths without pseudobulbs
GROWTH CYCLE/REST PERIOD: No rest period
LIGHT: bright (schlimii) to moderate (besseae)
TEMPERATURE: 58 degree night minimum; 78 degree daytime maximum
POTTING MEDIUM: premium sphagnum
HUMIDITY: very high, 80%
MOISTURE: constantly moist; water with low mineral content
TIPS: Because of their requirement for high humidity these are difficult to grow well on the windowsill. Reasonably easy for greenhouse growers who can adapt their methods to the plants' needs. A bit more challenging in areas with hot summers.Want to grow them in an Atlanta greenhouse? Invest in a max-min thermometer and an evaporative cooler.

Slipper Orchid Season

Phragmipedium schlimii

Now is a great time to see Andean Slipper Orchids in full bloom in the Tropical High Elevation House.

Phragmipedium schlimii & P. bessseae grow on mossy rocks of the waterfall

The Andean Slippers Phragmipedium schlimii and P. besseae are two of the tropical counterparts of the familiar north temperate slipper, Cypripedium. (The other tropical slipper genera are Paphiopedilum, Mexipedium and Selenipedium.) In total there are about 20 species of Phragmipedium (pronounced frag-mih-PEE-dee-um) ranging from Mexico through northern South America.

Andean Slippers grow in the splash zones around waterfalls, along flowing streams and in rocky seepage areas on cool slopes in Peru, Ecuador and Colombia. We created the waterfall and the flowing stream in the Tropical High Elevation House in order to provide suitable growing conditions for these orchids. They are wonderful!