Out of Africa

Angraecoids Curiosity

by Ken Slump

Posted by Sys Admin about 1 month ago.

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Orchid Riches from a Continent Where Almost Every Type of Climate is Represented


“I KNOW, IT IS ANOTHER STARRY white flower with a spur,” commented a friend who sensed me stifling a yawn after he enthusiastically led me to yet another of his favorite African orchids that was blooming in his greenhouse. While his comment was intentionally simplistic, it is true that orchids from Africa and Madagascar tend to lack the seemingly endless variety and wow factor of their popular counterparts from tropical Asia and the Americas. Still, there are many unique and beautiful orchid species from this part of the world. 

And a large and varied part of the world it is. Africa extends about 5,000 miles (8,040 km) from the Mediterranean on its northern boundary to Cape Town at its southern tip. It is a continental land mass second only to Asia in size. The equator nearly bisects the continent. As you would expect, virtually every type of climate is represented. Warm temperatures and seasonal moisture typify many of the climatic zones in Africa. While some of the largest deserts in the world are found here, tropical rainforests exist too, particularly near the coasts, along rivers and on mountain slopes.

ANGRAECOIDS  Those starry white flowers with a spur, more accurately the species and hybrids from the genus Angraecum, are often the first that come to mind if you ask someone to name an orchid from Africa. Most authors seem to agree that there are upward of 200 species in the genus, and as with any group so large, a simple phrase to describe the blossoms of them all is doomed to inaccuracy. Indeed, they are not all white flowered. Among Angraecum species, flower color varies. White, cream, light yellow and pale green are the colors most often noted. Such light-colored flowers attract night pollinators, particularly moths, and many are sweetly fragrant. Plant and flower size within the genus vary greatly, but they do all have a spurred lip. 

The genus Angraecum is part of the Vanda alliance. These orchids have monopodial growth habits and are mostly epiphytic. The smaller types may be grown mounted; larger ones potted. Many are of easy culture once established and thrive if given a somewhat cooler rest period after flowering. 

Among the larger-growing species is  Angraecum sesquipedale, a perennial favorite. It is sometimes called the comet orchid because of the flower’s long spur, which may extend up to 14 inches (35 cm). The spur contains a small nectary at its tip. The plant can easily grow to 3 feet (.9 m) and carries two ranks of closely spaced 12-inch (30-cm) leaves along its stem. The inflorescence may carry several long-lasting, fragrant flowers, and the plant usually blooms in winter. Orchid growers never tire of telling friends and orchid newcomers of Charles Darwin’s connection to this orchid. Darwin studied and published on orchid pollination mechanisms in the mid 19th century. When confronted with this flower, Darwin proposed that its pollinator, as yet unknown, would be a moth with a long proboscis that could reach the length of the spur to its nectary. When the moth was finally discovered decades later, the plant received the species name Praedicta.

Angraecum sesquipedale comes from the warmer lowlands of Madagascar. It seems to thrive when grown in a rather large pot and left un-disturbed. Intermediate conditions and moderate light levels suit it well. 

Growers with limited space might seek a plant of Angraecum compactum, also from Madagascar. A mature, branched plant may grow to 1 foot (30 cm) and carries thickened leaves just 2 or 3 inches (5 or 7.5 cm) in length. 

The large flowers often occur in pairs and have a spicy fragrance during the evening hours. Angraecum compactum could grow well as a mounted plant. It does best in cool to intermediate temperatures and shady, humid conditions. 

A large branch of the angraecoid clan is represented by the genus Jumellia, with more than 60 species. Most occur in Madagascar and the neighboring Mascarene and Comoros Islands. Like their cousins, Jumellia species produce a star-shaped white, fragrant flower with a long spur. The flowers are usually borne singly, but often in great abundance. 

Jumellia comorensis has a somewhat straggling growth habit. It has been found growing epiphytically on the trunks of rough-barked trees. While its fragrant flowers are not produced in profusion, more than one source says that it blooms almost continuously.

Aeranthes is another worthy angraecoid genus that occurs through much the same range as Jumellia. There are perhaps 40 or more species in the genus. Every orchid lover seems to appreciate the fascinating flowers of these plants. These rainforest denizens seem to do their best in hanging pots with a fast-draining medium. Intermediate to warm temperatures suit them well. Shade or filtered light is ideal. The plants are best grown hanging so that the blossoms can be enjoyed on their wiry, pendulous inflorescence. Flowers are often borne singly, in succession. They are usually white to creamy yellow or greenish. Most Aeranthes flowers are somewhat thickened centrally with rather short, pointed sepals and petals, which lends them the appearance of a large insect or a small amphibian dancing on air. 

The sequential-flowering Aeranthes grandiflora comes from Madagascar and sports yellow-green flowers. The green-flowered Aeranthes caudata tends to produce multiple flowers at one time and is native not only to Madagascar but also the neighboring Comoros Islands.

Another related genus of vanda-ceous orchids features some worthy genera that were once a part of the genus Angraecum, but were later incorporated into a genus of their own. Aerangis includes about 50 variable species, many with horticultural value. Because of their generally small to medium stature, many Aerangis species are ideal candidates for mounted specimens if a sufficiently buoyant, humid atmosphere can be created. Semishaded conditions are often desirable. Similar to Angraecum, Aerangis flowers are usually white, fragrant and long-spurred. A number of species are noted for their arching, exceptionally graceful inflorescences.

The boundaries of humid West African forests are a common home for Aerangis biloba, which received its species name for its broadly double-lobed leaf tips. The pendulous inflor-escence carries up to 15 waxy white fragrant flowers. It tolerates a wide range of light conditions, from shade to sun.

Perhaps the showiest of the genus, indeed one of the gems of the African orchid flora, is Aerangis luteoalba var. rhodosticta. This showy miniature ranges across equatorial Africa, but is nowhere common. It seems to frequently grow on the smaller branches of trees overhanging rivers and waterfalls, always in sheltered, shaded sites.

The small plants seem to thrive best when mounted. The species may be somewhat short lived, as some report difficulty in keeping plants alive for more than a few years. Shade and humidity are likely your keys to success. 

When in flower, Aerangis luteoalba var. rhodosticta is eye-catching. The inflorescence carries from one to two dozen flat, creamy white flowers with rather wide sepals and petals that are nicely rounded. Each flower’s most dazzling feature, however, is its bright red column. When the flowers are produced in large numbers, they leave an unforgettable impression. 

These few suggestions are indeed the tip of the iceberg when it comes to spurred starry white flowers that are native to Africa. Collectors may look to the genera Mystacidium, Summer-hayesia, Rangaeris, Diaphananthe and Cyrtorchis, and others, for additional options. While their themes may be similar, each interpretation is unique.

POLYSTACHYA  To find more colorful African orchids, Polystachya is a good place to begin. This genus includes more than 120 species. While most occur in tropical Africa, a few are distributed in Asia and the American tropics. Most are modest-sized epiphytes and produce terminal inflorescences consisting of several to many smallish flowers. The flowers of Polystachya are what botanists term nonresupinate, or inverted. This means that the orchid’s lip is held uppermost, which can give the flower an upside-down appearance. 

Polystachya bella is one of the most attractive. Its erect, often-branched inflorescence may produce 25 or more golden yellow to pale orange flowers, each usually less than an inch (2.5 cm) in size. The species grows in the moist, shady rainforests of Kenya and is reputedly undemanding of culture and deserves to be more widely grown. 

Polystachia vulcanica is an even less common, but nevertheless inter-esting species. It hails from an area called The Impenetrable Forest in a rugged area of western Uganda, so named when colonial surveyors determined that they could not establish clear sight lines through it in order to draw boundaries between Congo, Tanganyika and Uganda many years ago. This species has tightly clustered narrow pseudobulbs topped by a single linear leaf. From a distance, the appearance is grasslike. Its small pinkish flowers are accented with a purple lip and anther cap. 

ANSELLIA  For a bolder orchid statement from Africa, it would be hard to top a well-grown-and-flowered example of Ansellia africana. This robust epiphyte is of easy culture and can quickly reach specimen proportions if given a sufficiently spacious container. While several species were once listed for this genus, most now regard it as one variable species. It is sometimes called leopard orchid after its spotted flowers. Large, branched flower spikes carry many flowers that are usually yellow with various degrees of fine to bold brown or burgundy spotting. Indeed, some examples are so heavily spotted that they are almost entirely dark colored. The species ranges across most of south-central Africa. Ansellia africana has fragrant flowers and typically blooms in the spring months. When in active growth, water it generously if the medium is well drained. Intermediate growing conditions will suit it and, like other orchids from seasonally moist areas, a drier rest period is suggested. 

CYMBIDIELLA  Cymbidiella pardalina (syn. rhodochila) is another colorful orchid that comes from the rain forests of Madagascar. It has had a reputation as a fussy plant, but you will probably find that if you can avoid disturbing its roots, it grows and flowers quite satisfactorily. This species lux-uriates in warm, humid conditions and good light. In spring, the plant produces a raceme of many flowers that are a showy apple green color with contrasting red lips. The petals and yellow throat of the lip are usually darkly spotted. For best results, grow Cymbidiella pardalina without a rest period. Repot only when necessary and try to avoid root damage at repotting time. 

DISA  Finally, for brightly hued African orchids, you need look no further than the South African genus Disa. The best-known species is Disa uniflora, but the genus is rather large and includes more than 150 species. (See related story on pages 520–527.) While many orchid hobbyists are familiar with Disa uniflora, few grow it because of its unique requirements, which are quite different from the tropical orchids most choose to cultivate. In nature, it is found growing terrestrially along stream banks in the Cape provinces of South Africa. Plants seem to tolerate a wide range of light conditions, from partial shade to full sun, but cool temperatures are required. The pH of the water in which they grow is quite low and the plants seem quite intolerant of salts. Disa uniflora grows to a height of about 3 feet (.9 m). 

The blossoms are large, up to about 4 inches (10 cm). Flowers in the scarlet shades are most familiar, but pink, orange and yellow forms exist. It is sometimes called the Pride of Table Mountain after the many plants that once grew on this landmark near Cape Town. Because of its showy flowers, Disa uniflora has enjoyed interest from orchid breeders and hybridizers. 

It is possible that a number of orchid growers do not have a single African orchid. If you ask an orchid grower to conjure an image of wild Africa, you will undoubtedly get a reference to the continent’s incomparable animal life. But I think it is fair to say that its diverse orchid flora is equally as deserving as its fauna.
 

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