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January 2001 This Month ONT will focus on: "Species of the year - Houlletia brocklehurstiana 'Imperial Topaz' AM/SAOC" Written By Mr. Christo
Page. At a the Judges Forum in October 1999 the AM/SAOC awarded to Houlletia brocklehurstiana 'Imperial Topaz' of Christo and Aletta Page was ratified and the plant was chosen as the species of the year. What makes the Houlletias so special? The following background and cultural information may be of some interest: The genus Houlletia sonsists of about ten species that occur in the central and northern parts of South America to Central America, i.e. Brazil and Bolivia in the south to Guatemala in the north. The plants are characterized by one-leaved pseudobulbs and erect or pendulous inflorescences with anything from a few to about ten large, colourful flowers. The single leaves are large and generally plicate and the pseudobulbs are ovoid. Houlletias seem to be fairly rare in nature and consequently also not plentiful in cultivation. The fact that they are known to be difficult to cultivate probably also accounts, in part, to their comparative rarity in cultivation. They grow in humid to wet, cool cloud forests on the flanks of the Andes and other mountain ranges. Some species grow mainly epiphytically and others mainly terrestrially.
Houlletia brocklehurstiana 'Imperial Topaz' AM/SAOC Photographer: Christo Page
The three species most frequently mentioned in literature are Houlletia odoratissima from Panama to Bolivia, Houlletia tigrina (syn. Houlletia lansbergii) from Guatemala to western Ecuador and Houlletia wallisii on the eastern slopes of the Andes in Colombia, Ecuador and Peru.
Houlletia brocklehurstiana occurs in Brazil and, according to the scanty information available, grows terrestrially on steep embankments.
A division of what must have been a larger plant of this species, was bought in September 1991 at the 8th SAOC show in Durban as a direct import from Brazil.
The plant was planted in a rockwool/polystyrene mixture in a basket and is being grown under controlled conditions in a greenhouse. Temperature is controlled between 13ºC and about 28ºC and humidity stays above about 50% throughout. The plant is watered once a week in summer and once in 10 days during the winter. It gets fertilized with every watering. Once a month clean water is used to flush the growing medium.
The plant flowered for the first, and thus far, the only time in March 1997. A robust, erect flower stem of 365mm carried seven large, fleshy flowers. The flowers had an overall horizontal spread of nearly 80mm and, although somewhat nodding, made a striking display in shades of white, creamy brown and red brown. The lip had a white base colour intensely spotted with black.
The cultivar name 'Imperial Topaz' was derived from an exquisite and very costly Brazilian semi-precious stone occuring in lovely shades of light to darker champagne - the shades forming the base colour of the sepals and petals of Houlletia brocklehurstiana.
Fairly soon after the magnificent display of flowers which led to it being judged, the plant rapidly declined in health. This necessitated drastic measures of cleaning it from old rotten pseudobulbs and repotting it in a more porous growth medium of about 60% milled polystyrene, 10% perlite and 30% milled rockwool. The plant is now clawing its wat back to better health.
This episode once again showed that the advice to water plentifully during the growth season and maintaining a moist growth medium and high atmospheric humidity throughout the year should be treated with caution for most orchids and especially for the 'soft' leaved types. These orchids include other genera in the Gongora Tribe, e.g. Cynoches, Mormodes, Gongora, Acineta, Paphinia, Peristeria etc. Other groups of similar disposition are in the Maxillariae Tribe, Sub-tribe Zygo-petalinae, e.g. Bollea, Cochleanthus, Huntleya, Kefersteinia, Pescatoria etc.
Most of these orchids grow in very humid to wet cloud forests and some species have actually been observed by the writer to grow in sopping wet soil embankments. These conditions are not easy to duplicate in cultivation - during the rainy season the plant leaves and roots are very wet but, because they are in effect being bathed in running water, potential pathogens are washed away. As soon as the rain stops, the sun re-appears and the mild to warm temperature and brisk air movement dry the plants out. Also, plants growing under a thick canopy of leaves (many of the orchids with large, soft leaves) and near or on the main trunks of trees do not get wet at all but derive their sustenance from the very high atmospheric humidity. Orchid habitats are also seasonally wet and dry.
It, therefore, seems as if it is essential to grow Houlletias in a very porous medium or epiphytically while maintaining high humidity in the atmosphere, good air movement and no temperature extremes. A slightly drier regime in winter may also be advantageous. Good quality water is also necessary for soft leaved orchids as they quite easily show chemical leaf burn.
P. O. Box 32167 Glenstantia 0010
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