Tonight, Thursday, April 21 2016, Phyllis Prestia of San Diego spoke to the Desert Valley Orchid Society on the Orchids of Madagascar. She also showed a lot of photos of lemurs and the wonderful accommodations, but I will write here only of the orchids. I took these notes while Phyllis was speaking. Any mistakes are mine.
Madagascar has about the land surface area of Texas, and runs north to south about the length of California. The east coast runs almost due north-south.
Eastern trade winds blow constantly on Madagascar, bringing year-round moisture to the east coast. A high mountain chain runs, north to south, not far inland. West of the island's mountain spine most of the moisture has been lost to rain, so the central and western parts of the island are much dryer, and do not get rain from the east. The great majority of Madagascar's orchids are in the wet eastern rain forests. [An audience member observed there are Jumellea and Vanilla spp. in the central region.]
Phyllis went on a tour that covered some of the wet east coast of the island.
Most of the orchids she saw are angraecoids. She saw a few terrestrials and some others. Most Angraecum, Oenoiella and Jumellea species are native to Madagascar. There are several hundred Bulbophyllum species in Madagascar. There are seven Vanilla species native to Madagascar, and the Central American V. planifolia is widely cultivated for vanilla beans. V. madagascariensis is used to produce vanilla flavoring. It is more intense and a little more bitter than V. planifolia.
There are roughly three climate zones in the east as the land rises: the low and warm coast, the cooler midlands, and the cold highlands. All three zones receive plentiful rain all year, and there is no dry season in any of these regions. The orchids are accustomed to very pure water in the form of rain, dew or mist. There are a lot of birds, lemurs and reptiles in the forest, so epiphytes get small amounts of animal dung as fertilizer on a regular basis.
Coastal rain forest
On the coast, temperatures may reach 100 F / 38C during the day. It does not cool down much at night. There is a constant steady breeze from the east. Humidity is around 65% most of the time when not raining. Rain falls almost every afternoon, but the wind dries out orchids on trees relatively quickly. The trees in forests leave plenty of sky between their canopies, so there is bright light with moving sun and shadow.
Growing orchids from this zone involves keeping them warm, giving the epiphytes very bright light, watering epiphytes plentifully and regularly, but ensuring they dry rapidly after watering.
There are a number of twig epiphtyes in this zone (and in the other zones.) The twig epiphytes here get wet in the rain every afternoon/evening, and dry the next morning in the onshore breeze. After this trip she took her Tolumnias out of bark in pots and began watering them like this, and they stopped dying. She suggested setting Tolumnias in small empty pots. [Tolumnias are coastal twig epiphytes from the Caribbean region that have similar rain and wind in habitat.]
Many people who have trouble blooming orchids from this region don't give enough light.
Phyllis showed photos of these orchids growing in this zone (in the order she showed them
Oenoiella polystachya - growing high on the leeward side of a palm tree very close to the coast.
Angraecum eburneum - on the same side of the same palm.
Oberonia disticha - grows upside down. Dry by afternoon, warm wet nights after the late afternoon rain.
Another twig epiphyte, identity uncertain - ? Angraecum aloifolium? No flowers.
At the edge of an inland lake at low elevation, in this zone, they saw Nepenthes madagascariensis, a carnivorous pitcher plant, growing in full sun.
She also saw Benthamia humbertii, Cynorkis hologlossa and a Habenaria species in this zone growing as terrestrials.
She saw Angraecum viguierii, the only colored Angraecum, as well as Cymbidiella rhodochila and Graphorkis concolor growing epiphytically. There are three species of Cymbidiella, all endemic to [occurring only in] Madagascar.
Angraecum sesquipedale also comes from this zone. Hers began blooming when she got back from this trip and put it in the part of her greenhouse that gets full morning sun.
Midlands rain forest
Temperatures become cooler, to jacket weather at higher elevations. There is constant rain or dew, so these plants stay wetter all day. Humidity is over 50% to 90%. The forest is denser than the coastal forest, but usually not closed with deep shade. Light varies from dappled light to almost deep shade.
Twig epiphyte Oeonia rosea - very wet, but roots out in the air.
Cynorkis ridleyi epiphyte.
Bulbophyllum sp brevipetalum? Covered an enormous amount of a huge tree trunk and branches.
Jumellea punctata epiphyte.
Oberonia disticha again - here it is cooler and wetter all the time, but still grows upside-down.
Way up in tree Aerangis fastuosa.
Bulbo analamazoatrae, an endemic.
Microcoelia gilpinae, a leafless orchid, a wet twig epiphyte.
Jumellea confusa, Jumellea gracilipes as epiphytes.
High elevation rain forest
This region is cold and wet all the time. Daytime temperatures are in the 50s F / 10-15C. Nights are cold but never freezing; at night you can always see your breath fogging. Relative humidity is 90% or higher all the time. The ground is perpetually wet and slippery. The forest provides a closed canopy and deep shade. Water drips off leaves constantly.
Cymbidium lowianum, an introduced cloud forest species from Asia, was growing exuberantly and flowering as a decorative plant at one of the lodges.
Oberonia disticha again was growing in this zone, upside down, always wet, always cold. It is a very adaptable species.
Another Microcoelia sp. grew epiphytically.
There were a number of Bulbopyllum spp. growing epiphytically.
Angraecum magdalenae grew here in deep shade, very cold, very wet.
Cultivation notes:
Use very pure water: reverse osmosis, distilled, rain. Water all year - no dry season.
Temperatures as outlined above: Hot for coastal species, cold for high elevations species.
Regular light feeding for all of them.
Humidity as outlined above: 65% for coastal plants, higher for mid-elevation, 90% plus for high-elevation cold-growing plants like Angraecum magdalenae.
Lecture Notes: Phyllis Prestia: Orchids of Madagascar
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