Paphiopedilum wardii

Paphiopedilum wardii

Paphiopedilum wardii is a gorgeous olive green Asian Slipper Orchid native to Myanmar and southern China. I have always admired its coloration. But what's the story with the glistening bumps above the flower's pouch?

Several species of slipper orchids in the genera Paphiopedilum and Phragmipedium are visited by female hoverflies (Syrphidae). Female hoverflies select aphid colonies as brood sites for egg laying and their larvae eventually devour the aphids. John Atwood has observed hoverflies laying eggs on Paphiopedilum rothschildianum's staminode, which has raised glandular hairs. He concluded that the glandular hairs appear to the hoverflies to resemble the bodies of aphids. Atwood also observed the female hoverflies pollinating the orchid. This phenomenon--the attraction of female insects to false egg-laying sites in flowers --is called brood deception pollination.

Recently, Robert Pemberton has made several observations of hoverflies picking up pollina from Phragmipedium pearcei. Calaway Dodson also noted pollination of Phragmipedium longifolium by a hoverfly. Like most species of Phragmipedium, these two species have spots above the lip. It seems likely that the spots on Phragmipedium flowers attract hoverflies and facilitate brood deception pollination.

Is Paphiopedilum wardii pollinated by hoverflies? Is it pollinated through brood site deception? I don't know, but those glistening bumps would seem to suggest so.

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.

Polka Dots Are Back

Paphiopedilum bellatulum in the Fuqua Orchid Center

Of course they are. The slipper orchids in the Fuqua Orchid Center were rocking the dots weeks before polka dots made a big splash at September Fashion Week in New York.

Scary spotted slippers in London. Photo by Mark Leibowitz

Paphiopedilum bellatulum (top) scores extra points with us for having gorgeous spotted flowers and leaves. We love the downy texture of the flowers and flower spike. It grows natively in the crevices of limestone outcrops in Myanmar, Thailand and southwest China. 

Autumn is a great time to see a cool-weather flush of flowers on the slipper orchids (with and without spots) in the Orchid Display House and the Tropical High Elevation House.

Mimicry & Slipper Orchids

Paphiopedilum glanduliferum, a tropical slipper orchid that grows on limestone cliffs  in New Guinea

I'm often asked if our slipper orchids are carnivorous. They are not. The pouch of the slipper orchid is instead involved in a fairly gruesome pollination mechanism.

Many tropical Asiatic slipper orchids are pollinated by flies. The spots, bumps, hairs, carrion colors and foul odors produced by the flower attract flies seeking a food source. 
Paphiopedilum glanduliferum is pollinated by hoverflies (Syrphidae) which normally lay their eggs on aphid colonies. Aphids are the food source for the larval hoverflies. The glandular hairs in the center of the flower may mimic an aphid colony.

Pollination takes place when the hoverfly becomes trapped in the pouch of the flower. The escape route forces the hoverfly in close contact with the pollen masses. As a result the fly often departs for another flower with the pollen attached to its body.

We don't have hoverflies in the Fuqua Orchid Center. Even if we did we would prefer to hand pollinate our orchids (using a pencil, very low tech) so that we know which plant contributed the pollen and on what date. A "controlled cross," in other words.

There are always Paphiopedilum orchids in flower in the Fuqua Orchid Center. We will be happy to point them out to you.

Our Kennel of Bulldog Paphs

"Bulldog" Paphiopedilum hybrids displayed on the Cube in the Orchid Atrium

Probably the most popular orchids on the hanging Cube in the Orchid Atrium are the Asian Slipper Orchids, the paphiopedilums, or "Paphs." These particular Paphiopedilum hybrids are colloquially known as "bulldog Paphs" on account of their broad-faced flowers and drooping petals. Among the most famous of the bulldogs is Paphiopedilum Winston Churchill. You can read more about this famous hybrid here.

The bulldog Paphs make outstanding display orchids. Their enormous shiny flowers are mesmerizing when viewed at eye level and they are extraordinarily long lasting (for Paphs, anyway)--eight weeks if you can keep the daytime temperatures at or below 72º.

Paphiopedilum species in nature are usually, but not always, terrestrial. They often grow as understory plants, or wedged into crevices in rocky limestone or granite outcrops. Adapted to an environment where there is a fairly dependable reservoir of moisture surrounding their roots, Paphs are not as drought tolerant as their epiphytic relatives, like Cattleya and Laelia, which often possess thickened leaves to resist moisture loss and pseudobulbs to store water.

Thus, in cultivation, Paphiopedilum orchids enjoy more subdued light, a more moisture retentive medium, and more frequent watering than Cattleya orchids.  They do well under lights or on an east facing windowsill. On a windowsill they will need a few hours of mild morning sun in order to flower. Most growers pot their Paphs in a mixture of fine grade bark, charcoal and perlite, often with some additional peat or milled sphagnum.

You won't want to miss these extraordinary orchids. And don't forget your camera!

The Garden is now open every night until 7 pm. The Orchid Daze display runs through April 15.

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!