Tree of the Week: Sago Cycad
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The Sago Cycad – Cycas revoluta
The Sago Cycad, also known as King Sago Palm, is a living fossil, a relic of a once glorious past. In their heyday (Dinosaur times, 252 million to 265 million years ago), Cycads, together with other Gymnosperms such as the Conifers, constituted the dominant vegetation on earth. But in mid Cretaceous the upstart Angiosperms, better equipped to deal with the environment by enclosing their seeds inside a protective cover, started developing fast and left all other plants behind. Today only about 750 Gymnosperms remain to compete with an estimated 422,000 Angiosperm species, and several Cycad species within the Cycadaceae, Stangeriaceae and Zamiaceae families are close to extinction.
The Sago Cycad has been a popular container and landscape plant for centuries. We usually see it here as a short, squat, palm-like tree, with a trunk to 12 inches in diameter and up to 10 feet tall. Offset young plants may grow from the bottom to create a beautiful multitrunk plant as wide as tall. A rosette of glossy dark green, feathery, palm-like compound leaves to 45 inches long, surrounds the top of the trunk. They have little barbs on their stems and stiff, narrow, leaflets curved at the end. Blue colored and variegated leaf specimens are rare. The trees are dioecious, (two houses) meaning that male and female flowers occur on separate plants. The male flower stalk appears on top of the tree and looks like an overgrown elongated yellowish pine cone, the female flower structure like a similar pine cone squashed flat. All parts of the plant but especially the bright red seeds are poisonous to pets, other animals and people. The tree is somewhat drought-resistant; it does not like wet feet and is best watered infrequently like a cactus.
Most Cycads are slow-growing, long-lived, evergreen plants, naturally occurring in many tropical and subtropical areas of the world, including parts of Africa, South America and SE Asia. The Sago Cycad itself comes from Southern Japan. The tree contains some starch in its tissues, just like the true sago palm, Metroxylon sagus, an actual palm tree whose sago provides an edible starch. But the Sago Cycad is unrelated to palms, which are Angiosperms. Even repeated soaking of its sago and seeds as practiced by native peoples may not remove all its toxins. Blue green algae, living symbiotically with the tree within aerial rootlets, may simultaneously provide it with nitrogen fertilizer and toxin.
-- Pieter Severynen