Angraceoids by Joyce Stewart
Joyce began by saying that she and her husband had spent altogether 22 years in Africa, where most of the angraecoid orchids are found, 11 in Kenya and 11 in South Africa and from these two bases they had evidently travelled widely. During the course of her talk, we saw slides of orchids photographed in Madagascar, Reunion, the Central African Republic, Malawi and Gabon (and probably other places your reporter didn’t catch).
Her first slide was of a huge plant of Angraecum eburneum var. giryamae, growing on a vertical limestone cliff, east-facing and in full sun. Other slides showed the symmetrical arrangement of the flowers on the spike, with the lips of the flowers uppermost and the spurs pointing down. The variety Ang. eburneum longicalcar has longer spurs of some 12 – 18 inches long. Ang. conchiferum has smaller flowers with even longer spurs. Ang. germinianum, like most of the angraecums, likes to be able to grow into a big plant and Ang. sesquipedale really can grow enormous. This species, from Madagascar, has leaves with a blue-green bloom on them and usually, but not always, has a pleasant scent. It can sometimes be quite unpleasant. This is the one which Darwin famously predicted would be pollinated by a moth with a long tongue, since it is night-scented and has ivory-white flowers with very long spurs. He was eventually proved right when the moth was discovered but it is not generally known that Darwin had never actually seen a live flower of the plant, only a dried specimen.
There are some 220 species of Angraecum and we were shown a selection of the smaller ones: Ang phoroides, a small West African species; Ang zeigeri whose flowers are tinged with bronzy-green; Ang ruthenbergianum (syn. elephantinum, didieri) from Madagascar with large flowers for the size of the plant; Ang eichlerianum from West Africa with distinctly square-lipped flowers; and several others.
Then we saw a range of related genera starting with an Angraecopsis, the flowers on long peduncles. These like to be constantly damp. Cyrtorchis arcuata has flowers which change colour from white to primrose yellow after pollination. Diaphananthe pellucida has long chains of delicate-looking small flowers with fringed lips. Bubbles of air can often be seen in the nectar in the spurs. There are two species of Eurychone, Echn galeandrae from the Congo, is pink and Echn rothschildiana from Uganda, is greenish. Jumellea walleri from Malawi, like all the Jumelleas, has single flowered spikes with only the dorsal sepal pointing upwards, the rest of the floral parts point down. This needs high humidity and plenty of fresh air. Microcoelia species are odd in having no leaves – the roots turn green when wet and they can photosynthesise. Mcrcoel exilis has small spurs; Mcrcoel obovata, like the other species, comes from an area with seasonal dry periods but even then there is water from the daily condensation of dew.
Mystacidium capense, from Natal, was growing in the canopy of an acacia tree; Mycdm venosum has similar flowers but smaller, with tangles of roots. Plectrelminthus caudatus grows among ferns, grasses and rocks in seasonally dry areas. It needs no compost at all in cultivation, preferring its roots to be exposed. Its flowers have lips uppermost. Species of Tridactyle have characteristically three-lobed lips with the lobes sometimes fringed.
Joyce then moved on to her special favourites, the Aerangis species. These are always epiphytic. A number of these she has herself described and named, singly or with others. Aergs carnea was one of these. It comes from Madagascar and has slender floral parts. Aergs distincta (J. Stewart and I.F. La Croix) has petals smaller than the sepals and has distinctively notched leaf tips. She had also described and named Aergs montana which comes from Tanzania and has pale green flowers which become white as they mature and Aergs punctata which has small grey-green leaves punctured with minute silvery dots.
We saw many others, at least a dozen, including some spectacular Aergs citrata and Aergs mystacidii, ending with the very attractive Aergs luteo-alba var. rhodosticta, its white flowers with their characteristic bright red central columns. This was shown to be more variable than many suppose it to be.
There were one or two questions and Joyce was thanked and suitably applauded by the audience. Ted Croot