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Dioon

Fact sheet: Chestnut Dioon

 

Dioon edule is the most widely available, as well as the most-cold hardy of the uncommon cycads grown in Florida. This species prefers sandy conditions in full sun, but performs well in virtually any soil type with good drainage. It has a high tolerance to salt and has the general appearance of the king sago, except with lighter green foliage. Some varieties have lavender, pale-blue, or pale-red emergent leaves. Old plants have multiple trunks and can reach 6-8 feet in height.

Cycads are ancient, palm-like, evergreen gymnosperms (cone-bearing plants) of the Division Cycadophyta. Represented by three families—Cycadaceae, Stangeriaceae, and Zamiaceae—the cycads are composed of approximately 200 species in 11 genera—Bowenia, Ceratozamia, Chigua, Cycas, Dioon, Encephalartos, Lepidozamia, Macrozamia, Microcycas, Stangeria, and Zamia.

Although many cycads superficially resemble palms, these two groups of plants are in no way related. In fact, cycads are more closely related to pine trees than to palms. During the age of the dinosaurs cycads were the most abundant plants on Earth, whereas palms did not show up on Earth for another 150 million years.

Cycads are dioecious plants, which means that there are separate male and female plants. Female plants produce seeds and male plants produce cones full of pollen. Many of the cones on cycads are highly ornamental, like the bright red cones of Encephalartos ferox (see below).

One of the reasons that cycads have survived for so long is that they can grow in harsh conditions. Many cycads naturally grow in pure sand or even on bare rock. Some can withstand hard freezes every year, as well as snow. Others live in areas that receive no more than a couple of inches of rain per year.

Dioon edule is probably the most cold-hardy of all the cycads. In the 1989 freeze, parts of Lakeland, FL, got down to 17°F. Most king sagos were completely defoliated, while D. edule plants only experienced tip burn.

Many cycads are also salt tolerant. For example, in a particular habitat in Mexico, Dioon plants hang over a cliff and are constantly assaulted with salt spray from the Gulf of Mexico.

With our sand- and limestone-based soils here in Florida, it can be difficult to grow some types of plants. However, the majority of cycads thrive here. As a result, cycads make perfect, easy to maintain plants for our landscapes. In fact, one cycad species is native to Florida. The common name for the plant is “coontie”, which is a Seminole name. These plants are adapted to the Florida weather and thrive in our sandy soils.

Planted in Nassau County Extension Demonstration Garden