An exotic beauty

Madagascar. The name rolls around in your mouth with a lyrical exoticism.

It is estimated that more than 80 percent of the flora and fauna on this isolated island nation near Africa is unique to the island.

Madagascar is the fourth-largest island in the world behind New Guinea, Borneo and Greenland. With its variety of ecosystems and relative isolation, Madagascar has given rise to some strange creatures.

All of the world's lemurs are there, and two-thirds of the world's chameleons. And Madagascar is home to some of the strangest plants on Earth.

There is the well-known bottle-shaped baobab tree. The spiny forests in the southwest support a variety of weirdly swollen and heavily armored plants, including the genus pachypodium.

Prized by cactus collectors, succulent collectors — and masochists — these plants are so densely arrayed with patterned thorns that it hurts to look at them.

But the bizarre also is tempered by the beautiful. Such is the case with the comet orchid Angraecum sesquipedale, a flower whose biology imbues it with an uncommon grace.

Louis Marie Aubert du Petit Thouars, a French botanist exiled to Madagascar and the Réunion islands during the French Revolution, discovered the comet orchid and hundreds of other species. He introduced them in 1802 when he returned to France and contributed the majority of his collection to the Jardin des Plantes in Paris.

The flowers of this orchid are thick and waxy, almost appearing as if carved from paraffin. The sharply pointed bud is trailed by a circular nectar spur that unrolls to nearly 10 inches long once the flower opens.

The flowers are star-shaped and glossy white. The name refers to the long nectary. Sesquipedale means 1½ feet. This is a bit of an exaggeration, but the nectary also gives rise to the common name comet orchid, the spur resembling a comet's tail. Other common names for the flower include star of Bethlehem orchid, Christmas star orchid and Darwin's orchid.

Charles Darwin, the father of evolution, developed a theory about the pollinator of this flower when he first encountered it in 1862.

Darwin thought there must be a moth with a proboscis long enough to reach into the tip of the long spur of the nectary to drink its sweet reward and pollinate the flower.

He was proved right, but not until 1903 — 21 years after his death — when the moth was found. The moth is a large hawkmoth, looking somewhat like a cigar with hummingbird wings.

The moth was named Xanthopan morganii praedicta to recognize Darwin's "prediction." The intimacy exhibited between this orchid and its pollinator is one of our finest examples of co-evolution between plant and pollinator. It exhibits the importance of keeping all the pieces if the picture is to remain whole.

Other plants in this genus also have unique pollination strategies. Researchers from Kew Gardens have recently documented the first known instance of pollination by a cricket in a species of Angraecum, and there are others that are pollinated by birds.

Plants in the Angraecum family exhibit a great deal of diversity. Certainly the comet orchid is the most spectacular. An epiphyte, it is found growing in the trees of coastal forests in its native environment.

Most other species are epiphytic, too. Some, such as Angraecum eburneum, carry their flowers on lengthy stems in long rows.

This plant also exhibits a common trait among many Angraecums of displaying their flowers upside down. Others bear just a few flowers that are miniature representations of their larger cousins.

Angraecum leonis is a compact stack of sickle-shaped leaves with large flowers relative to its size. Its nectary spur is arched. Then there is Angraecum distichum with tiny flowers about the size of Lincoln's nose on a penny.

The stems of this plant appear almost braided with tiny, sickle-shaped leaves from which multiple ivory-white flowers appear like tiny stars.

Others, such as Angraecum dideri, are ladder-shaped. The thick, waxy roots and leaves are staggered along the length of the ascending stems. These are built to climb and are found creeping along tree trunks or branches.

Many of these plants are suitable for your home. I grew the comet orchid for years, and it flowered annually. It benefits from a summer beneath a tree and any extra humidity you can supply.

These plants like bright, indirect light, but they don't want to have the sun shining on them. They should be potted in a loose, well-drained orchid-bark mix. Water them once a week by giving them a warm shower in the sink. Eventually, the comet orchid will grow too large to handle comfortably in the home, but this is a gradual process, one that could take 20 years.

Angraecum leonis and A. distichum could be grown on a windowsill with some extra attention to humidity. A tray filled with pebbles and water beneath the pot is usually sufficient to supply extra humidity. Make sure the pot is never sitting in water.

One more fine quality of many of these plants: Since they are pollinated by moths, many are sweetly night fragrant. As the sun goes down, they slowly fill the air in their room with a subtle perfume, further adding to the mystique of one of Madagascar's most storied plants.