The Madagascar Greenhouse
Mexico and USA side of the greenhouse
250 millions years ago, there was only one continent : the gondwana. With the plates’ tectonics, the continents were separated the ones from the others, each one developing specific flora and fauna. Plants that were located on the Cancer and the Capricorn tropics and the equator developed similar shapes to resist to hot and desert climate. So we can compare the Cereus and the candelabrums, the aloes and the agaves.
These completely different species changed during millennia, losing their leaves and replacing it with spines or pivots. These plants are fleshy, which allows them to stock important water reserves to resist to dry periods.
Aloe helenae
Danguy
The example of Madagascar is unique in its kind. When the continents got formed, it was separated from Africa, keeping on its ground animals and plants that evolved in a different way from the rest of the world, promoting specific and endemic flora and fauna.
For 1 500 years, deforestation has been promoting food crops (rice, manioc, maize, coffee, vanilla, sugar cane and oleaginous plants), it contributed to uncover the lateritic ground. Madagascar’s nickname is "the red island"
On this island, there are 3 climatic areas :
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The eastern coast, wet and hot, it is occupied by dense forest
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The north-west side with its rainy period and dry period, promoting savanna
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The south-west side, which is sub-desert with the highlands that have a temperate and salubrious climate
Madagascar side of the greenhouse
The Botanical Garden, in its conservation role, imported the main part of the plants from Madagascar. Conditioned in the south of the island after their biotope was destructed (creation of roads, plantations…), they were acclimatised during one year and a half in our culture greenhouses before their definitive placement. Some of these plants, with a slow growth, are more than 60 years old!
The principle of dryness resistance is the same for the plants from Madagascar, Africa and America (they stock water in their tissues), the transformations are more varied and spectacular for the plants from Madagascar (fleshy leaves bunches, thorny candelabrums or "bottle trees").
Here are some of the plants you can find in the greenhouse:
Euphorbia pseudocactus
A. Berger
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The Alluaudia (Didieraceae family) genus gathers 6 tree species, if they are often thorny they still keep leaves
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The Moringa (Moringaceae family) : it comes from the south-west of the island, its nickname is "the flour bag" because of its white trunk that can reach a 2-meters diameter
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Encephalartos (Zamiaceae family): it is a primitive plant with a very slow growth. Rare in its wild environment, its disappearance has is fastened by the exploitation of its medulla : the Sagou, which is used to make the Kaffir bread
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Proteaceae : coming from tropical and austral Africa, the 115 shrub species are appreciated for their big inflorescences and they are cultivated for cut flowers trade.
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The Aloes come from Africa, Madagascar and the Arabic peninsula. This genus of succulent plant counts more than 300 persistent species of trees, shrubs and plants. They can be used in the cosmetics industry for their moisturising properties and in the medical industry for the calming substances contained in their sap.
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Euphorbia : this large genus counts about 2 000 species of annual, hardy herbaceous plants, shrubs and many succulent plants looking like Cactaceae. All spurges contain a milky sap (latex), very irritating for the sensitive skins and that can provoke and temporary blindness if it touches the eyes. The spines of the Euphorbia are gathered by 1,2 or 3.
Uncarina leandrii
Humbert
The Mexican and North American parts
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The Agaves are very decorative hardy plants, they make spectacular big floral stems and have frayed leaves often bordered with sharp-edged thorns. They are monocarpic, that is it takes them from 5 to 40 years to flower and they then die leaving shoots that will take their place. They are cultivated for many uses : the dried leaves’ fibre is used to make strings : the final spine is used as a sewing needle, the flesh of the leaves is transformed in alcohol giving tequila, pulque or mescal. The Incas also used this plant to torture some prisoners.
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Opuntia : this genus of the Cactaceae family is the largest and the most widespread with more than 200 species. It can be small prostrated plants with tuberous roots or 9-meters high trees. All the species wear on their top small leaves that quickly disappear. This plant has circular flattened stems allowing to stock water. The leaves can be eaten as a salad if they are made spineless.
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The Cereus: nowadays, the botanists divide the Cactaceae family by 130 genera and the genus Cereus that was formerly widespread is now restricted to 40 species. The true candles are generally straight standing cactuses, rarely crawling cactuses, they have multiple stems with a dozen of longitudinal ribs. The prickles groups are sparse and generally go by 5. Flowerings are often nocturnal, more rarely diurnal.