Trees Planet: Cycas thouarsii – Madagascar Sago

Monday, July 14, 2025

Cycas thouarsii – Madagascar Sago – Thouars Cycad

General Information

Common Name	Madagascar Sago Thouars Cycad
Scientific Name	*Cycas thouarsii*
Sun Tolerance	Full Sun
Height	Up to 7 m (up to 23 ft)
Spread	2 to 3 m (6 to 10 ft)
Growth Rate	Fast
Bloom Time	Summer
Color	Green,
Flower Color	Yellow
Type	Tree
Native	Africa, South-East Asia

Classification

Kingdom	Plantae – Plants
Subkingdom	Tracheobionta – Vascular plants
Superdivision	Spermatophyta – Seed plants
Division	Cycadophyta - Cycads
Class	Cycadopsida
Subclass	Cycadidae
Order	Cycadales
Family	Cycadaceae Pers. - Cycad family
Genus	Cycas L. – Cycad
Species	C. thouarsii L.

Cycas thouarsii – Madagascar Sago – Thouars Cycad

Cycas thouarsii, commonly known as the Madagascar Sago also known as Thouars Cycad, is a magnificent tropical plant belonging to one of the most ancient plant lineages on Earth—the cycads. With its grand, palm-like appearance and rich green foliage, this species stands as a testament to evolutionary resilience, having existed relatively unchanged for over 200 million years since the age of the dinosaurs. Cycas thouarsii is one of the most robust and fastest-growing cycads, particularly favored for landscaping and ornamental use in tropical and subtropical regions around the world.

Madagascar Sago is native to the islands of Madagascar, the Comoros, Seychelles, and parts of coastal East Africa, including Tanzania and Mozambique. It thrives in humid tropical environments, often growing near the coast, in forest clearings, or along riverbanks where soil drainage is good and sunlight is ample. The species has also been widely cultivated in Southeast Asia, the Caribbean, India, and Florida due to its adaptability and decorative appearance.

Cycas thouarsii is a large, evergreen, tree-like cycad with a prominent, woody trunk and a crown of large, pinnate leaves. It is often mistaken for a palm due to its similar appearance, but it is taxonomically distinct and much more ancient. The trunk is typically upright and columnar, reaching heights of up to 7 meters (23 feet) or more in mature specimens. The trunk surface is covered with diamond-shaped leaf scars, remnants of old fronds.

Thouars Cycad, leaves are pinnate, arching outward and slightly downward, often measuring 2 to 3 meters (6 to 10 feet) in length. Each leaf consists of numerous linear-lanceolate leaflets that are dark green, glossy, and leathery in texture. New leaves emerge in a central flush and are covered in rust-colored fuzz, which protects them as they unfurl.

Like other cycads, Cycas thouarsii forms coralloid roots that house nitrogen-fixing cyanobacteria. These roots appear as swollen, coral-like nodules near the soil surface and help the plant thrive in nutrient-poor soils.

C. thouarsii, like all cycads, does not produce flowers because it is a gymnosperm—a group of seed-producing plants that evolved before flowering plants. Instead, it reproduces using cones or cone-like structures and is dioecious, meaning individual plants are either male or female. Male Cone (Microstrobilus) A single, erect, cylindrical cone that can grow up to 50 cm (20 inches) long. It is covered with tightly packed microsporophylls that bear pollen. The cone is often yellowish or brown and emits a strong scent to attract pollinators. Female Structure unlike typical gymnosperms, the female structure is not a compact cone but a loose cluster of megasporophylls. Each megasporophyll is leaf-like and bears several ovules on its margins. After fertilization, large, orange to reddish seeds develop, typically around 3–5 cm in diameter. Pollination is mainly wind-assisted, but certain insects may also play a role. Reproduction is slow, and cones are produced only when the plant is mature, which may take 10 to 15 years or more.

Compared to other cycads, Cycas thouarsii has a relatively fast growth rate, particularly in tropical climates with abundant rainfall and warm temperatures. Under optimal conditions, the plant may grow 20–30 cm (8–12 inches) of trunk height per year. Cycas thouarsii can reach a height of 6 to 7 meters (approximately 20 to 23 feet) in ideal tropical conditions. In cultivation, it may grow slightly shorter depending on care, climate, and soil conditions. It is one of the taller species of cycads, with a stout, columnar trunk and a large crown of arching fronds that adds to its overall visual height. Cycads are known for their longevity, and individual plants can live for hundreds of years.

It has a great Ornamental Value, extensively used in landscaping, parks, resorts, and private gardens. Valued for its symmetry, hardiness, and tropical aesthetic. In some cultures, seeds have been used as a famine food, but only after careful preparation to remove toxins (cycasin). The seeds are toxic when raw and require boiling and fermentation before consumption. Some parts of the plant have been used in traditional medicine, although this is not common due to its toxicity. All parts of Cycas thouarsii contain cycasin, a toxic compound that can cause liver failure, neurological damage, or even death if ingested in sufficient quantities by humans or animals. Pets, especially dogs, are particularly vulnerable and should be kept away from cycads.

Cycas thouarsii is a living fossil and a tropical treasure, offering a unique glimpse into the prehistoric world of plants. Its bold, architectural presence, combined with its ecological importance and ancient heritage, make it a prized specimen for gardeners, landscapers, and plant lovers alike. With responsible care and protection, C. thouarsii can continue to grace our gardens and remind us of the deep roots shared by all living things on this planet.