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.

Pescatoria lehmannii

The phrase 'beautiful orchid' invariably conjures in my mind an image of this particular species.

It's not just the blue-violet perianth or the creamy citrus scent. On top of everything else, it's that lip, thickly carpeted with hairs, that makes Pescatoria* lehmannii extraordinary to me. That combination of beauty and quirkiness is irresistible.

So what's up with that lip, anyway?  Let's remove the petals and sepals and have a closer look.

Dorsal view. Pointing directly at us is the column and below it is that impressively hairy lip.

Turning the flower on its side, you can see that the lip has a distinctive raised thickening, or callus, at its base. The callus has ribs, called keels.

Dorsal view again, this time with the column removed. With the column removed you can get a better look at the base of the lip and the callus. The base of the lip has a deep opening outlined by the callus. In Pescatoria lehmannii the interior outline of the callus is an inverted M.

Turning the lip over to view its ventral surface, you can see that the lip actually has two side lobes rolled backward. At the base of the lip is the narrow claw, which joins the lip to the base of the column.

Here's the column in ventral view. Some pescatorias (the former Bollea species) have a column with lateral wings. Pescatoria lehmannii has a wingless column.

We grow Pescatoria lehmannii in a greenhouse with intermediate temperatures, 85% relative humidity and 80 % shade. It does well for us in a mixture of premium sphagnum and coarse shredded tree fern fiber. Since pescatorias (all Zygopetalinae, actually) hate root disturbance, I prefer to grow them in cedar baskets rather than plastic containers. After about three years, the basket disintegrates and becomes easy to remove with minimal root disturbance.

*I've updated the spelling of this genus to make it consistent with the International Plant Names Index.

Bucket Orchid Season

Our Bucket Orchids (Coryanthes) are producing a lovely autumnal flush of growth. Some pretty incredible flowers will follow in a couple of months. Here's one of the earliest, Coryanthes mastersiana.

Coryanthes mastersiana produces two to three flowers on each inflorescence. It somewhat resembles the Brazilian species Coryanthes speciosa, but the fragrance is very different. According to Günter Gerlach's website, Coryanthes mastersiana grows together with Coryanthes flava and Coryanthes elegantium in western Colombia and Ecuador.

Above is a diagram to help you make sense of the peculiar anatomy of Coryanthes flowers. The lip, often the most elaborate of an orchid's three petals, is modified in Coryanthes to facilitate pollination. The bucket, or epichile, fills with liquid from two glands protruding from sides of the column. At the rear of the bucket, and just visible in the photo, is an opening where the bucket meets the anther cap at the apex of the column.

When a male Euglossine bee scratches the surface of the hypochile in order to obtain liquid fragrance, he slips into the bucket. With his wings drenched, his only escape is to paddle to the rear opening and force his way through the small opening. In doing so, he rubs up against the sticky end of the pollinarium, which ends up attached to his body. At a subsequent Coryanthes the process is repeated, but this time he leaves the pollinia behind on the stigmatic surface of the column.

Coryanthes produce some of the most incredible flowers in the entire orchid family and this year I plan to set more capsules on our plants.

Stanhopea platyceras

This Stanhopea was the reigning queen of our greenhouse the last few days. We received it with the label Stanhopea napoensis, and so I placed it in our warm greenhouse, where it was growing, but not particularly well. This year it produced one enormous bud, angular in shape, almost like an Embreea bud. When it opened, behold: our plant is actually Stanhopea platyceras.

Stanhopea platyceras looks like no other Stanhopea in our collection. The entire flower is covered with plum colored dots that coalesce into inky blackness at the far end of the hypochile.

Stanhopea platyceras is endemic to Colombia, where it has been found growing at 1000 to 1500 meters elevation. No wonder it was unhappy in our warm greenhouse (65º  F night minimum).

Until recently we grew all of our Stanhopea species together in the same intermediate temperature greenhouse (60º F night minimum). It was convenient for us, but it wasn't really in the best interests of our stanhopeas. Over time, five degrees Fahrenheit makes a huge difference to plant. So I divided the collection between two (actually three) zones. We moved our warm growers, native to areas below 1000 meters, like grandiflora, lietzii and candida, to our 65º night minimum greenhouse. Species from 1000 to 1500 meters, the majority, stayed in the intermediate greenhouse receiving 60º night minimum. Cooler growing species I try to group closer to the wet wall in our intermediate greenhouse.

This is just one way to grow Stanhopea species, tailored to a hot temperate climate like Atlanta's, where the night minimum outdoors is often 72º F in July and 20º in January. For a completely different perspective, check out Rob Laurie's blog, in which he describes growing stanhopeas outdoors year round in southern California.

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.

Peristeria

Peristeria (unidentified) species flowering in the Fuqua Orchid Center. Visible inside the flower are the broad yellow lip and the tip of the column.

If this orchid looks a bit familiar perhaps it reminds you of the Dove Orchid, Peristeria elata. The generic name, Peristeria, is derived from the Greek word 'peristerion' (dove) and refers to the dove shape that is formed by the fusion of the lip and the column.

The yellow almost-dove inside our Peristeria appears to be wingless because the lip lacks two large side lobes. In both species the lip is hinged and the weight of the pollinator (a Euglossine bee) landing on the lip causes the lip to rock. The bee is thrown against the end of the column--the dove's head--and in contact with the pollen masses.

What a terrific fragrance this orchid has! This Peristeria species smells like eucalyptus, but with a sweet floral aspect. The dominant chemical compound is eucalyptol (1, 8-cineole), a fragrance component of many Euglossine bee pollinated plants.

The 12 Top Holiday Questions

Whew. Our Garden Lights Holiday Nights display is finished! We threw open the doors Friday night and as visitors flowed through the Conservatory and Orchid Center we could see delight in so many faces. It was enormously gratifying and worth all of the hard work just to see those faces.

Everyone had LOTS of questions! So, from the Department of Frequently Asked Questions comes the following:

Q: How many Poinsettias does our gigantic Poinsettia Tree have?

A: Five hundred.
The Inside Scoop. Our eighteen foot tall tree has enough rings for 544 plants, but we have never used that many. We do a complete switch out of plants after four weeks, so a total of 1,000 Poinsettias will inhabit the tree during this holiday. The tree has an automatic irrigation system so that we don't have to hand water them all.

Q: What are the lovely lily-white flowers at the base of the tree?

A: Amaryllis Wedding Dance
The Inside Scoop. Amaryllis (Hippeastrum) are different from many other bulbs in that they don't require a cold rest--just a mild temperature drop--in order to flower. Find out how to grow Amaryllis here.

Q: How many plants grow on the Poinsettia Wall in the Conservatory Lobby?

A: Three hundred.
The Inside Scoop. Here are some tips for keeping your Poinsettia looking good throughout the holiday. First, remove your plant from its plastic sleeve immediately upon arriving home.  Plastic sleeves are the pits for Poinsettia bracts. Second, grow it warm--no colder than 62º at night and 70-75º during the day. Keep it in bright light, away from drafts and let it dry out a bit between watering. Follow the links to find out more about Poinsettia care and Poinsettia history.

Q: What is the wonderful fragrance in the Orchid Display House?

A: Angraecum eberneum subsp. superbum, an orchid native to Madagascar that is fragrant only at night. The entire bed is in flower now and the fragrance is heavenly.
The Inside Scoop. The fragrance is produced to attract a night-active pollinator--a hawk moth--that feeds on the nectar located in the flower's long spur.

Q: What's up with the Three Bears?

A: This year the family has adopted a pet dog! (Above right, enjoying his glow ball.)
The Inside Scoop. Only one visitor asked whether a family of bears might not be more likely to regard a dog as a potential dinner rather than as a pet. Certainly not. Our bears are vegetarians.

Q: What's Baby Bear's name?

A: He doesn't have one (yet). Please suggest one!

Q: Where do Mama & Papa Bear shop for clothes?

A: Bloomingdales.
The Inside Scoop. Not really. Tres Fromme, our Landscape Design & Planning Manager, made an undercover trip to Target to buy bear accessories, but only because he wanted to check out the store's selection of Transformers.

Q: What flower in the Orchid Display House smells like vanilla?

A: Oncidium Twinkle 'Red Fantasy'.
The Inside Scoop. The lovely yellow form of Twinkle is flowering above the reflection pond, and also smells like vanilla.

Q: What are the beautiful white orchids in the Orchid Atrium?
A:

Beallara Tahoma Glacier 'Green'

The Phalaenopsis Blast--one of two this holiday

Dendrobium Mini Snowflake (aberrans  x johnsoniae)

The Inside Scoop. Dendrobium aberrans is an adorable miniature that you can find flowering in the Tropical High Elevation House later this year.

Q: What are the festive plants on the trellis in the Orchid Display House?

A: Begonia Veronica & Nephthytis (syn. Syngonium) Holly.
The Inside Scoop. Begonia Veronica is a type of Rieger Begonia. It is a short day plant--meaning that it flowers naturally in winter. Nephthytis is a ridiculously easy houseplant.

Q: What is the trio of plants under the Poinsettia tree?

A: (Top to bottom) Poinsettia Freedom Red, Homalomena 'Green Gem,' Amaryllis Wedding Dance, Nephrolepis 'Green Fantasy.'

Q: What other wintry white orchids are in flower now?
A:

Angraecum longicalar

Laelia rubescens

Bring your friends and family and stop by! The Garden is open regular hours during the day. Garden Lights Holiday Nights opens nightly at 5 pm.

Happy Thanksgiving from The Fuqua Orchid Center

Stanhopea candida in the early morning light of the Fuqua Orchid Center

I want to wish everyone a Happy Thanksgiving and to thank you all for your continued support of the Garden, the Fuqua Orchid Center and this blog--your comments, email messages, your visits and your hard work on our behalf. I am thankful not only for our wonderful orchids, but also for all of our staff, volunteers, members and the amazing people I have met visiting the FOC and visiting this blog.

Have a wonderful holiday weekend!

Anguloa clowesii

Anguloa clowesii flowering at the Atlanta Botanical Garden

I love that some of our Tulip Orchids are flowering indoors while our Horticulture staff is planting actual tulips outdoors.

Tulip Orchids are Andean in origin. Anguloa clowesii is native to Colombia and Venezuela where it grows at 1800 to 2800 m on the western slopes of the Andes. It was collected in 1842 by Jean Linden near the Nevado of Tolima, a Colombian volcano. Alvaro Arango M. writes in Orchids of Colombia, Vol. I, that in order to throw other collectors off the trail Linden reported it to be from the Sierra Nevado of Santa Marta, a coastal mountain range much farther north and not a part of the Andean mountain chain. This sort of deception was a fairly common practice among competing collectors. Linden named his discovery after one of the British financiers of his expedition, the Rev. J. C. Clowes of Manchester. Linden and his son later founded one of the most profitable 19th century orchid collecting firms.

Autumnal Anguloa

Some of our Tulip Orchids (Anguloa) are producing a late season flush of flowers.

I'm unsure of the identity of this lovely Anguloa which is unfortunately missing its label. The lip (barely visible in the photos) has characteristics that are intermediate between a couple of species. It may be a hybrid. For the moment it is a question mark, but still beautiful.

I love that the coloration is more vivid on the interior of the flower than on the exterior--clearly it's intended for the private enjoyment its pollinator. It's hard to look at this flower without wondering how the pollinator, a euglossine bee, experiences the colorful pattern and fragrance.

Openings: Stanhopea frymirei

Stanhopea frymirei captured in the early morning light immediately after watering. Photographing a Stanhopea can require a lot of patience. The tiniest adjustment in the plant's position sets the basket swinging like a pendulum for an eternity.

Stanhopeas are extraordinary orchids. The flowers are elaborate, enormous and intensely fragrant. The fragrances are complex mixtures of floral, culinary and resinous scents. They are delicious!

At first glance a Stanhopea flower can be baffling. But like all other orchids they have three petals and three sepals. The elongated part with two eyespots and two white horns is the lowermost petal, or lip. Reflexed backwards like enormous wings are two sepals. The third sepal arches forward, pointing toward the four-o'clock position. Over the top of that sepal are the two remaining petals which roll inward toward each other.

The reproductive part of the orchid flower, the column, is greenish-tinged in the picture above. Together with the lip, it forms a chute that channels a visiting bee toward the pollen. The yellow pollen masses can be seen in the second photo at the far end of the column, backlit and glowing yellow.

Openings: Coryanthes alborosea

Coryanthes alborosea red form flowering at the Atlanta Botanical Garden

This vibrantly spotted and spattered orchid is one of the siblings of the Coryanthes alborosea that I photographed last week. The seedlings, which are now flowering for the first time, are the result of a selfing of the red splashed color variant. A small percentage of the seedlings look like their parent.

This is a plant that leaves me awestruck. If you tried to describe it to a friend what would you say? Do you think anyone would believe you?

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.