The Plant that Outlived the Dinosaurs

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Cycads thrived during the reign of the dinosaurs.

Cycads have a very long history. These palmlike plants first appeared some 280 million years ago, during the Permian period, and possibly even earlier, but they really took off during the reign of the dinosaurs some 30 million years later.

At that time, cycads were among the most common plants in the world and were found on all the continents and in all terrestrial environments from swamps to deserts and mountains. Movies featuring dinosaurs often show them munching on cycad fronds. However, the foliage of all modern cycads is very toxic and scientists believe that they adopted this foliar toxicity very early in their evolution, precisely to protect themselves from giant plant-eaters.

But although it’s possible dinosaurs couldn’t eat cycad fronds, it’s still believed that they played an important role in the plants’ survival. That’s because their large fruits are colorful, juicy and edible while the seed inside is toxic. The assumption is that the dinosaurs swallowed the fruits whole and digested their flesh, and then voided the still-intact seeds in their excrement, thus helping to spread the seeds throughout the dinosaur’s environment. This passage through their digestion system would also have helped cycad seeds germinate.

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Cycad distribution in the modern world.

The cycads almost disappeared along with the dinosaurs: of the thousands of species that inhabited the Earth at that time, only about 300 species in 11 genera still persist today. They are often considered living fossils: their slow growth and even slower reproduction mean they have a hard time keeping up in a world dominated by fast-growing  flowering plants. Thus, cycads are, for the most part, quite rare in the wild, growing only where other plants can’t survive.

Palmlike But Not Palms

Cycad (left), palm (right). You have to admit they look a lot alike!

There can be no denying that cycads look a lot like palm trees, what with their sturdy pinnate fronds and their thick usually unbranching trunks (for those species that produce trunks, that is). However they are no way related to palm trees. Palms are fairly modern plants most closely related to grasses and are therefore flowering plants. Cycads, though, are gymnosperms, close relatives of the conifers, although they don’t look much like our image of a conifer! The link to conifers becomes much clearer, though, when you see that cycads produce cones much like pinecones.

Female cone of the Japanese sago (Cycas revoluta) on left, male cone on right.

Cycads are dioecious, that is to say that there are separate male and female plants… but you’ll only be able to tell the sex of your cycad when it reaches maturity and that can take 20 years or more! Male cones are often fairly upright and convincingly phallic in shape while female cones vary in form: sometimes they’re quite conelike, but sometimes they look more like furry cabbages!

A Cycad for Your Living Room

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Young Cycas revoluta: the size most often available in stores.

Surviving for 280 million years has left most cycads extremely well adapted to tough growing conditions and most do very well in one of the most hostile environments of all: inside our homes. But first you have to find one!

One of the rare cycads that is commercially available as a houseplant is the Japanese sago or Japanese sago palm (Cycas revoluta). (The one other that is sometimes seen is the “cardboard palm”, Zamia furfuracea, a smaller clumping species with round-tipped leaflets).

As its name suggests, the Japanese sago comes from Japan, specifically islands in the southern part of the country. It is considered threatened due to overharvesting on its islands of origin, but not likely to become extinct any time soon, as it is widely grown outdoors as an ornamental plant in subtropical and mild temperate climates all over the world. It is hardy to zone 9, but can be grown in colder zones as long as periods of freezing are not too extreme nor prolonged.

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The Japanese sagos in this grove are over 100 years old.

Although the Japanese sago can theoretically reach up to 23 feet (7 m) in height, it’s very slow growing and reaching such a size could take a century or more. Indoors, it will remain at a very reasonable size for decades. Curiously, the entire year’s new fronds appear all at the same time, in late spring, forming an outward arching crown all around the trunk. This is very different from the palm trees, which produce one single frond at a time.

Its dark green, waxy, pinnate fronds are tough with a pointed tip and spines on the petiole. They can range in length from 4 inches (10 cm) on young plants to 5 feet (150 cm) on mature specimens. They can spear you quite readily: you won’t want to place this plant where you’re liable to back into it!

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An older plant with a distinct trunk.

Its rough trunk may appear rounded and pineapplelike on young plants, but becomes distinctly trunklike as it grows. Mature specimens sometimes produce offsets and become multi-trunked, but that is rarely seen indoors.

A curious detail: like many cycads, Japanese sagos produce normal roots which dig into the soil and spread out in all directions like those of any other plant, but also specialized roots called coralloid roots which form on the surface of the soil and are inhabited by cyanobacteria. The latter fix atmospheric nitrogen and share it with the plant, allowing it to live very well in poor soil. For that reason, cycads need little fertilizer.

Culture

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Japanese sago: a snap to grow!

The Japanese sago has a reputation for being a very easy-to-grow houseplant, indeed almost unkillable. Young plants with a barely visible, still rounded trunk, are often sold in garden centers, as are more mature specimens where the trunk is more clearly defined.

Although adapted to both full sun and dense shade outdoors, this plant prefers bright conditions indoors, nothing less than medium light, with as much sun as possible over the winter. If possible, place your plant outside for the summer, but do make sure to acclimate it gradually to outdoors conditions to avoid leaf burn.

It’s highly adaptable to indoor temperatures as well: it will grow just as readily in a blazing hot sunroom as a barely heated spare room. Just don’t let it freeze!

As for watering, just follow the Golden rule and thoroughly moisten the soil when it’s dry to the touch.

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Japanese sago grown in a bonsai pot.

If you want to see your Japanese sago grow as rapidly as it can, repot it every 3 or 4 years, changing the potting soil and gradually increasing the size of its pot. Keeping it in a small pot will tend to dwarf it and that is sometimes the goal, notably when the plant is used in bonsai.

This plant requires little fertilizer. Perhaps one or two applications of an all-purpose fertilizer at 1/8 of the recommended rate each year.

Keep this plant out of the reach of both children and pets, as it is both spiny and poisonous if consumed.

Propagation

Put propagation out of your thoughts, at least indoors.

The Japanese sago only rarely produces offsets that you could remove and root on their own… and it takes decades before it begins to flower. Even then, you’d have to have a male plant and a female plant in bloom at the same time and transfer the pollen from the male to the female yourself to get seeds!

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Cycad seed sprouting.

The only logical way of multiplying this plant yourself would be to obtain fresh seeds, sometimes available on the Internet. Germination is very slow (it can take up to 6 or 7 months), but relatively sure. On the other hand, the seeding’s slow growth means it will take them 4 to 6 years before they start to show a trunk.

For these reasons, I suggest you buy your Japanese sago as a plant… better yet, as a plant of about the size you want. Waiting for a young one to grow up can become a bit tedious.

Look Before You Leap

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Leaf infested with mealybugs.

Do make sure you check any cycad thoroughly before you buy it to be certain that it’s free from unwanted travelers. Indeed, both mealybugs (looking like little pieces of cotton batten) and scale insects (small brown bumps on the leaves) love cycads and you won’t want to bring these insects home. Even if you checked the plant thoroughly first, it’s always wise to keep not just cycads but any new plant in isolation for 40 days before you put it in with your other houseplants.


There you go: a plant that is slow-growing, but reliable, easy to grow and very original. And it will never be eaten by dinosaurs, I promise!

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