Madagascar holds one of the most distinctive collections of plants on the planet, and the large majority of its species are endemic, meaning they grow nowhere else.1PubMed. Madagascar’s extraordinary biodiversity: Evolution, distribution, and use Walk through its forests and you see whole plant families and shapes found on no other landmass. Many of these plants also still carry traits shaped by giant animals that vanished centuries ago, so parts of the flora are adapted to a world that no longer exists.2Biological Conservation. The ghost fruits of Madagascar: Identifying dysfunctional seed dispersal in Madagascar’s endemic flora Much of it now survives in shrinking patches of habitat.
How Many of Madagascar’s Plants Are Found Nowhere Else
About 83% of Madagascar’s ferns, flowering plants and other vascular plants grow only on the island.3Wikipedia. Flora of Madagascar Among trees and shrubs the share is even higher, with as many as 96% estimated to be endemic.4Wikipedia. Flora of Madagascar Five entire plant families exist only in Madagascar.5Wikipedia. Flora of Madagascar
It helps to separate “endemic” from “native.” Native means a plant grows naturally in a place. Endemic means it grows only there. A plant can be native to both Madagascar and Africa, but then it is not endemic. When endemism is high, losing local habitat means losing the species worldwide, because there is no other population to fall back on.
Most islands have unique species, but very few have unique plant families. Five families found nowhere else point to a very long stretch of isolation and separate evolution.
Many species are also narrow endemics, confined to one forest or one massif.6European Journal of Taxonomy. Revision of the Madagascan endemic Homollea (Rubiaceae – Pavetteae), with description of two new species Homollea is a group of shrubs and small trees whose five species all grow in dry forests of western and northern Madagascar, often on limestone.7European Journal of Taxonomy. Revision of the Madagascan endemic Homollea (Rubiaceae – Pavetteae), with description of two new species With ranges that small, all five are rated Endangered or Critically Endangered.8European Journal of Taxonomy. Revision of the Madagascan endemic Homollea (Rubiaceae – Pavetteae), with description of two new species
Why Madagascar Grew So Many Unique Plants
Madagascar was once joined to India and Africa as part of the supercontinent Gondwana. That is why rainforests in South India and Madagascar share some ancient plant lineages.9Journal of Biogeography. Diversification and divergence of rainforest woody plants in South India and Madagascar relate to geomorphological history But the number of shared lineages fell steadily as Madagascar split off and became more isolated.10Journal of Biogeography. Diversification and divergence of rainforest woody plants in South India and Madagascar relate to geomorphological history
Many people imagine the island as a frozen piece of dinosaur-era Gondwana. In reality, no plant group studied so far has proven old enough, at more than 80 million years, to have simply ridden the island away from Gondwana.11Annual Review of Ecology, Evolution, and Systematics. Has Vicariance or Dispersal Been the Predominant Biogeographic Force in Madagascar? Only Time Will Tell Most flowering-plant families with members in Madagascar are relatively young.12Annual Review of Ecology, Evolution, and Systematics. Has Vicariance or Dispersal Been the Predominant Biogeographic Force in Madagascar? Only Time Will Tell So most ancestors likely arrived later as seeds carried by wind, birds, or ocean currents.
The evidence fits this picture. Sedges reached Madagascar in many separate arrivals, and some lineages spread back out again, with distance limiting how often this happened.13Journal of Biogeography. The evolutionary history of sedges (Cyperaceae) in Madagascar A group of the coffee family’s herbs could only have arrived by long-distance travel within the last 66 million years.14PubMed. Dispersing towards Madagascar: Biogeography and evolution of the Madagascan endemics of the Spermacoceae tribe (Rubiaceae)
Madagascar lies across a wide channel from Africa, so a seed has to survive a long trip. It might be blown by wind, carried in a bird’s gut or feathers, or floated on a raft of vegetation. Very small seeds and spores, like those of ferns and orchids, ride air currents far more easily than large heavy seeds. Seeds that float and tolerate salt water, as many coastal plants do, suit ocean crossings better than seeds that rot or sink.
One arrival can become many species. A seed that lands on an isolated island meets new soils, new climates and few competitors. Its descendants spread into wet forest, dry forest and mountains and slowly diverge. Because isolation keeps fresh arrivals rare, local lineages develop undisturbed, and over millions of years one ancestor can give rise to many distinct species.
The Island’s Range of Habitats, From Rainforest to Spiny Thicket
South-easterly trade winds bring cloud and heavy rain to the east all year.15Missouri Botanical Garden. Biogeography and endemism of the Northern Humid Mountains of Madagascar So lowland rainforest covers the east up to about 800 m.16Missouri Botanical Garden. Biogeography and endemism of the Northern Humid Mountains of Madagascar Moist mountain forest takes over between 800 and 1,800 m, and tougher, hard-leaved forest grows around 1,800 to 2,000 m.17Missouri Botanical Garden. Biogeography and endemism of the Northern Humid Mountains of Madagascar The summits of the major mountains carry a low heath-like scrub of their own.18Missouri Botanical Garden. Biogeography and endemism of the Northern Humid Mountains of Madagascar
In the west, dry deciduous forest grows in canyons cut through jagged limestone known as tsingy.19Encyclopedia of Earth. Madagascar dry deciduous forests Rosewood, figs and the baobab Adansonia madagascariensis dominate the canopy there.20Encyclopedia of Earth. Madagascar dry deciduous forests The limestone tops suit succulents such as Pachypodium and several Euphorbia species.21Encyclopedia of Earth. Madagascar dry deciduous forests
The driest areas, with 300 to 600 mm of rain a year, grow dense thicket rather than grassy woodland.22Perspectives in Plant Ecology, Evolution and Systematics. Interpreting some outstanding features of the flora and vegetation of Madagascar Even these dry areas have some chance of rain all year and fairly humid air, so succulents are abundant across the thicket, not only on rocks.23Perspectives in Plant Ecology, Evolution and Systematics. Interpreting some outstanding features of the flora and vegetation of Madagascar The Didiereaceae, a family of spiny plants, evolved fleshy stems, fleshy leaves and column shapes while keeping normal wood.24TAXON. Four succulent families and 40 million years of evolution and adaptation to xeric environments: What can stem and leaf anatomical characters tell us about their phylogeny?
Famous Plants of Madagascar
Madagascar has seven baobab species, the bottle-trunked trees of the genus Adansonia.25PubMed. Not all species will migrate poleward as the climate warms: The case of the seven baobab species in Madagascar They handle drought in different ways: A. rubrostipa and A. grandidieri cope with arid ground better than A. madagascariensis as seedlings.26South African Journal of Botany. Water use strategies of seedlings of three Malagasy Adansonia species under drought
The swollen trunk stores water, which helps the tree get through the long dry season. Baobabs also drop their leaves in the dry season to cut water loss, so a bare baobab is normal and not a sign of illness.
Nepenthes madagascariensis is a carnivorous plant of the east coast that traps prey in jug-shaped leaves.27Journal of Tropical Ecology. Prey composition of the pitcher plant Nepenthes madagascariensis About 80% of its prey are ants, with flies and beetles making up most of the rest.28Journal of Tropical Ecology. Prey composition of the pitcher plant Nepenthes madagascariensis Lower pitchers catch more ants, while upper pitchers catch more flying insects.29Journal of Tropical Ecology. Prey composition of the pitcher plant Nepenthes madagascariensis That is because young plants form ground-level pitchers near crawling ants, and climbing stems later make upper pitchers that reach flying insects.
Each pitcher becomes a tiny pond community. Mosquito larvae, mites and fly larvae live their whole lives inside the pitcher fluid, feeding on drowned insects.30Biotropica. Structure and Dynamics in Nepenthes madagascariensis Pitcher Plant Micro-Communities The mites hitch rides on adult flies to reach new pitchers.31Biotropica. Structure and Dynamics in Nepenthes madagascariensis Pitcher Plant Micro-Communities
The Madagascar periwinkle, Catharanthus roseus, is now a common garden and bedding plant across warm regions worldwide.32PubMed Central. Ornamental Exterior versus Therapeutic Interior of Madagascar Periwinkle (Catharanthus roseus): The Two Faces of a Versatile Herb It is also grown commercially in the US, Spain, China, India and elsewhere for medicine, because it contains more than 130 related alkaloids.33PubMed Central. Ornamental Exterior versus Therapeutic Interior of Madagascar Periwinkle (Catharanthus roseus): The Two Faces of a Versatile Herb Two of these, vincristine and vinblastine, are cancer drugs.34South African Journal of Botany. Madagascar periwinkle alkaloids: Biosynthesis, ethnobotanical attributes, and pharmacological functions
The plant in your garden may be sold as vinca or periwinkle, in pink and white. It is different from the trailing ground-cover periwinkles of cooler gardens. Every part of it contains those alkaloids, so it should not be eaten or used as a home remedy, and children and pets should be kept from chewing it. The cancer drugs are purified in labs, not taken from leaves.
Plants Shaped by Lemurs and Vanished Giants
The traveller’s tree, Ravenala, has big flowers locked in tough bracts that a strong animal must pry open.35American Journal of Botany. Pollination of Ravenala madagascariensis (Strelitziaceae) by lemurs in Madagascar: evidence for an archaic coevolutionary system? Its stiff flower parts withstand rough handling, and it pours out plenty of sugary nectar.36American Journal of Botany. Pollination of Ravenala madagascariensis (Strelitziaceae) by lemurs in Madagascar: evidence for an archaic coevolutionary system? Ruffed lemurs visit it almost exclusively, carry pollen on their fur, and leave the flowers intact.37American Journal of Botany. Pollination of Ravenala madagascariensis (Strelitziaceae) by lemurs in Madagascar: evidence for an archaic coevolutionary system?
Madagascar lost many large animals in recent millennia, including giant lemurs and elephant birds.38Biological Conservation. The ghost fruits of Madagascar: Identifying dysfunctional seed dispersal in Madagascar’s endemic flora So the largest-seeded plants may now have no animal with a mouth big enough to swallow their seeds.39Biological Conservation. The ghost fruits of Madagascar: Identifying dysfunctional seed dispersal in Madagascar’s endemic flora Seed sizes of these giant-seeded plants still match where megafauna once lived.40PubMed Central. Legacy of the Lost and Pressure of the Present: Malagasy Plant Seeds Retain Megafauna Dispersal Signatures but Downsize Under Human Pressure Palm groves that once shared more of these giants are genetically more alike, a sign seeds once moved long distances.41Journal of Ecology. Genomic signatures of past megafrugivore‐mediated dispersal in Malagasy palms But where human impact is heavy, the largest seeds are disappearing along with large fruit eaters.42PubMed Central. Legacy of the Lost and Pressure of the Present: Malagasy Plant Seeds Retain Megafauna Dispersal Signatures but Downsize Under Human Pressure
Many woody plants of the southern thickets, across 25 families, grow tangled, wiry, springy branches.43PubMed Central. Springs and wire plants: anachronistic defences against Madagascar’s extinct elephant birds These look like defences against browsing by giant birds, much like plants in New Zealand that faced moas.44PubMed Central. Springs and wire plants: anachronistic defences against Madagascar’s extinct elephant birds
Threats to Madagascar’s Plants
More than 80% of Madagascar’s original forest cover has been lost.45Trillion Trees. #Forests2Follow: Madagascar, A Haven of Biodiversity and Cultural Heritage The main driver is tavy, slash-and-burn farming.46Trillion Trees. #Forests2Follow: Madagascar, A Haven of Biodiversity and Cultural Heritage A patch of forest is cut and burned, and the ash briefly fertilises the soil so that a crop, often rice, can be grown. After a few seasons the soil is exhausted, so the family clears another patch, leaving the old one to regrow slowly if at all. For families with little land and few alternatives, it is a way to feed themselves, so reducing it depends on offering other ways to farm.
Erratic rainfall lowers farm yields and pushes families to clear more forest to make up the shortfall.47PubMed Central. Predicting Plant Diversity Patterns in Madagascar: Understanding the Effects of Climate and Land Cover Change in a Biodiversity Hotspot What remains is often damaged: fragmented forests and forest edges have fewer tree species and smaller trees than intact forest.48Biodiversity and Conservation. Forest fragmentation and its associated edge-effects reduce tree species diversity, size, and structural diversity in Madagascar’s transitional forests Only about 10% of the east coast’s littoral forest remains, and just 1.5% of those fragments are protected.49PubMed. Deforestation and plant diversity of Madagascar’s littoral forests
Fire has also reshaped the highlands. Much of the central grassland may have been forest burned by people, and pollen shows grass overtook trees by about 1000 CE. Other scientists argue some grasslands are ancient, with 30 to 40% endemic grasses. Either way, the fire-tolerant grasses there offer poor feed for cattle.
Rosewood and ebony are prized for musical instruments and furniture.50TRAFFIC. CITES CoP19 Madagascar’s Rosewood and Ebonies Between 2010 and 2015 over 350,000 trees a year were cut in protected areas and over 150,000 tonnes exported illegally.51TRAFFIC. CITES CoP19 Madagascar’s Rosewood and Ebonies Corruption and instability have allowed rules that ease illegal logging.52Biological Conservation. Uplisting of Malagasy precious woods critical for their survival Buyers can ask for proof of legal origin before purchasing rosewood or ebony items.
Climate change adds pressure. Of 74 endemic plants modelled, 45% are projected to lose range by 2080 and only 18% to gain.53Biology Letters. Climate change adaptation for conservation in Madagascar Narrow endemics and habitat specialists fare worst.54Biology Letters. Climate change adaptation for conservation in Madagascar Six of seven littoral forest plants studied could lose 98% or more of their range in at least one projection.55Biology Letters. Climate change adaptation for conservation in Madagascar Four of the seven baobabs could lose over 70% of their range by 2085 under high warming if they cannot spread.56PubMed. Not all species will migrate poleward as the climate warms: The case of the seven baobab species in Madagascar Keeping habitat patches connected matters, so plants can move to suitable areas.
How People Use and Protect Madagascar’s Plants
Rural communities keep detailed knowledge of medicinal plants for common illnesses.57PubMed Central. Medicinal plants used to treat the most frequent diseases encountered in Ambalabe rural community, Eastern Madagascar In one coastal forest community, men gather medicinal plants and women dry, store and prepare them for family care.58PubMed Central. Medicinal plants used by women from Agnalazaha littoral forest (Southeastern Madagascar) Plants are food too: in the southwest, six endemic wild yam species are eaten, and about 70% of households collect them.59PubMed Central. Effects of socio-economic household characteristics on traditional knowledge and usage of wild yams and medicinal plants in the Mahafaly region of south-western Madagascar
Nine communities in the southwest co-manage Tsinjoriake, a protected area set up formally in 2015.60Community Conservation. Extending Community Protected Areas – Madagascar Its spiny forest holds plants from 126 genera, many found only there.61Community Conservation. Extending Community Protected Areas – Madagascar The communities’ work includes restoring forests and mangroves and teaching environmental education.62Community Conservation. Extending Community Protected Areas – Madagascar For the littoral forest, 15 large fragments holding about 41.5% of what remains were recommended for protection.63PubMed. Deforestation and plant diversity of Madagascar’s littoral forests
Visitors and gardeners can help in small ways. Choose tours that support community reserves and local guides. Never take seeds or plants home, since it can be illegal. Buy cultivated, not wild-collected, succulents and orchids, and ask for certified timber.