Institute of Food and Agricultural Sciences
Hendry County Horticulture News
Cycads Provide an Exotic Prehistoric Look
The Steven Spielberg movie "Jurassic Park" presented a realistic and terrifying look at some of the incredible animals that once roamed the earth during the Cretaceous and Jurassic Periods (65-180 million years ago). In the story, scientists isolate dinosaur DNA from the stomachs of blood-sucking insects preserved in amber. From the DNA blueprint, dinosaurs are cloned and roam an island off the west coast of Costa Rica. While such a scenario is highly implausible and we are unlikely to see the rebirth of these "terrible lizards", a number of plants which shared the ancient landscape with the dinosaurs are still thriving and can provide an exotic prehistoric "land before time" look to modern landscapes.
Perhaps the most remarkable of all seed plants that flourished during the days of the dinosaurs are the cycads. These bizarre plants were so numerous in Mesozoic times that this era is often called the "Age of Cycads and Dinosaurs." The king and queen sago, the cardboard palm and the native coontie are all survivors of this ancient time. Because of their tropical aspect and graceful habit, cycads are highly regarded by knowledgeable gardeners.
The stems of cycads may be completely subterranean or emerge from the ground and form a slow growing columnar trunk, 3 to 50 feet tall, and a crown of leaves that superficially resembles a palm. The leaves of most cycads are once divided (pinnate) and often develop an attractive palm like crown. Though cycads are often known by the name palm, they are not closely related to the palms. Unlike palms, cycad trunks produce rings of xylem (wood) tissue surrounding a wide, pithy central core. Palm trunks do not produce concentric growth rings. There are over 150 species of cycads in 10 genera, mostly in tropical and subtropical regions of the world (some of the Australian, Mexican and African species grow in arid habitats).
Cycads are dioecious with pollen cones and seed cones produced on separate male and female individuals. In some species, the enormous pollen and seed cones can reach 3 feet in length and may weigh up to 90 pounds, the largest of all living cone bearing plants. Prior to the theory of continental drift, the widely scattered distribution of present-day cycads in Australia, South Africa, Malaysia and the New World was an enigma. How could cycads have such a worldwide distribution when their seeds are too large, heavy and dense to be carried great distances by birds, wind, or ocean currents? When cycads thrived on earth, the continents were united into an enormous super continent named Pangaea (approximately 200 million years ago). Evidence from plate tectonics shows that large plates of the earth's crust are slowly moving, resulting in today's isolated continents and widespread distribution of cycads.
Although most cycads are restricted to warmer growing areas, several including the king sago (Cycas revoluta) and the native coontie (Zamia floridana) are hardy through out the state. The king sago is characterized by stiff glossy dark green leaves and make an excellent albeit slow growing ornamental specimen. The coontie is a low growing herbaceous perennial which produces feathery fern like foliage from a large underground storage root. This hardy native makes an excellent low growing foundation plant and creates a unique atmosphere when planted by pine in wooded settings. The queen sago or fern cycas (Cycas circinalis) is palm like in appearance and produces long dark green feathery leaves atop a stout unbranching trunk. This large graceful cycad is better suited for planting in warmer areas as it is easily damaged by hard frost. The cardboard palm (Zamia furfuracea) is a native of Mexico that is widely used as an evergreen shrub or ground cover. Like many cycads, it forms a typical rosette with stiff broad leaflets. The cardboard palm is more cold tolerant than the queen sago and can be safely planted through out most of our area, although it may be left leafless after a hard freeze. Several other less common cycads can sometimes be purchased in area nurseries.
In general, cycads tolerate a wide range of well drained soils, and have low nutritional requirements although some, particularly the king sago, may develop micro nutrient deficiencies on alkaline soils which results in off-color distorted leaflets. Although many cycads can be grown in direct sunlight, most will perform best in partial shade. Some, like the coontie, will do well in deep shade. As a rule most cycads are drought tolerant. Cycads are relatively pest free but are occasionally attacked by scale or mealybugs.
Most cycads can be propagated from seed. Be sure to use fresh seed and remove the brightly colored flesh for best results. Some like the king and queen sago can also be multiplied by division.
Although they once represented a dominant and very successful plant line, many of today's relict cycad populations are seriously threatened with extinction due to extensive collecting and diminishing habitats. Indeed, the plight of today's cycads is shared by many endangered plant and animal species that once flourished in vast, pristine ecosystems. Our native cycad, the coontie has suffered this fate and has been collected out of existence in many of it's original habitats. Due to poaching of wild plants, the coontie has been granted legal protection in Florida. Plants are readily available from cultivated sources and should never be taken from the wild.
Turn back the clock a few million years and add a prehistoric aspect to your landscape. Good luck and good gardening.
Gene McAvoy is the horticulture agent with the Hendry County Extension Service. Direct your horticulture questions to PO Box 68, LaBelle, FL 33975, e-mail - firstname.lastname@example.org or phone 863-674-4092 or 863-983-1598. You are also welcome to visit the Hendry County Extension Office at 225 Pratt Blvd., LaBelle. Office hours are from 8:00 - 5:00.
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