Types of Cycads

There are eleven different genera of cycads. Each genus (singular of genera) is a main category of cycads.  Within each genus there are typically many species.  In other words, with the species Encephalartos horridus, Encephalartos is the genus and horridus describes the actual species. Classification beyond species would be a variety. The purpose of this article is not to describe the differences between the genera. Rather, suffice it to say that these genera are all quite different from each other and tend to be native to a specific part of the world. In other words, Zamia species come from the Americas whereas Encephalartos species originate in Africa and Lepidozamia species come only from Australia. Cycas species have a much wider distribution from Asia south through the Pacific Islands into Australia. 

From a landscape and culture point of view, each genera appear different and have different cultural requirements. Because of this, there is a diversity of cycad plants that can be used in various areas of a garden or they can be used in different climatic conditions. Some species like hot dry sun, others like filtered light. Some like very moist conditions, others like it dry and some are more cold hardy. What this means to the gardener is that there are probably some cycads you can grow. Of course, extremely cold weather can be fatal to almost any cycad. Not withstanding severe cold, most gardens can accommodate one of the various genera.

Thus, we have genera of cycads that not only look different from each other, but also like different types of growing conditions. And, there are differences among the various species of a given genera. Below are some general comments about the various cycad genera, their appearance, and their cultural requirements.

Bowenia
A group of smaller, subterranean cycads from Australia that have a unique bipinnate (branching) leaves. This is typically an under-story group of cycads and require filtered light or possibly full sun in sheltered coastal areas. There are two, (possibly three) species. They are quite interesting but a bit difficult to grow. We would recommend Bowenia for the more sophisticated collectors.

Ceratozamia
Native to Mexico, Belize and Guatemala, Ceratozamias are unique plants that tend to have native mountain habitats and various morphological shapes. Some have narrow leaflets, while others have somewhat wide leaflets. Some leaves are erect while others are pendulous and almost lay on the ground. With approximately twelve to fifteen species, Ceratozamia tend to have smaller trunks compared to other types of cycads and often these trunks are subterranean. Trunks on a few species like Ceratozamia robusta can get head height and branch. Most species require some protection and filtered light. Ceratozamia plumose is quite unique with needle-like leaflets that appear to swirl along the petiole. Ceratozamia hildae is a very attractive species with grouped leaflets. This genus of cycads offer a unique addition to that somewhat protected part of the garden.

Chigua 
With only two species in this genus, Chigua are essentially unavailable on the commercial market. Native to Columbia, this genera has tropical requirements and is essentially a greenhouse species for most areas. 

Cycas
A widely diverse group of beautiful cycads with a distribution ranging from Japan, west through China and the Indochina countries to India and south through the Pacific Islands to northern Australia. Local habitats range from under story or tropical localities to harsh sunny grasslands. This genus is probably the most palm-like of all the cycads and often form vertical trunks with emerging pinnate leaves. Some can get quite tall. Typically leaves are green, but some species have gray or blue leaves. There are even species with multipinnate or branching leaves. The common Sago Palm, Cycas revoluta, is a member of this genus. Many tolerate full sun while others want protection. Cycas female cones are different in appearance from female cones of other genera. This group is sought after because of its landscape appeal.

Dioon
Dioons are a genus native almost exclusively to Mexico, with only one species from Central America. They have cylindrical trunks, but can occasionally be round or ovoid. In general, their leaves are not overly long and most species have green or gray-green leaves. Most species prefer full sun. There are a few, like Dioon spinulosum and Dioon mejiae that like protection from blasting sun. The sun loving species such as Dioon edule have a good amount of cold hardiness. Although there are plants in habitat that can have twenty feet of trunk, most plants grown domestically don't have the age or maturity to be that large and are quite manageable in the garden. Therefore, they are popular because they are not overly large and can tolerate a range of cultural conditions. Although taxonomists disagree, there are somewhere between ten and fifteen Dioon species.

Encephalartos
Encephalartos are the most popular group of collectible cycads worldwide. This probably results from their diverse appearance and sizes. Some are small, others are large. Some have vibrant green leaves while others are as blue as the sky. Some have unique prickly leaves like no other plants. Native to Central and South Africa, there are more than fifty species with more being described as time goes by. Many species develop majestic trunks that may branch overhead. Many have huge crowns of leaves, almost looking like a large palm tree. Some develop red, orange or yellow cones that fascinate even the novice collector. Most species prefer full sun although a few prefer filtered light. Some protection is recommend for desert growers on many species. Some species have good cold tolerance, but care must be taken in selecting species right for your area.

Lepidozamia
This group of cycads are native to Eastern Australia and there are two species. Lepidozamias are user friendly cycads in that the petioles and leaflets are unarmed with no spines. They get very sizeable trunks with many decades of growth, making this genus the largest trunked genera in the cycad world. Even juvenile plants with five to ten years in the ground can make sizeable crowns of leaves. It is important to give Lepidozamias enough growing room because of the length of the leaves. This genus likes strong light or full sun along the Coast. Growers in inland areas should provide part-day sun or filtered light. Propagation is by seeds as this genus essentially does not put out basal suckers.

Macrozamia
This genus consists of about thirty species, all from Australia. Some taxonomists divide this into two sections, including Macrozamia and Parazamia. The former group tends to be larger species while the latter are smaller and often subterranean. Leaves are pinnate and the Macrozamia section can develop very large trunks. This genus can assume the appearance of a palm tree. Most species are sun loving and many are quite cold tolerant. Several species develop overhead trunks. Macrozamia macdonnellii from the central Northern Territory of Australia are beautiful blue plants demanding full sun. As a genera, Macrozamia are quite adaptable to different garden environments and easy to grow.

Microcycas
Microcycas are a unique type of cycad with only one species native to Cuba. Plants are extremely rare and this is a true collector cycad. Old plants can have overhead trunks and can branch. The leaves are pinnate with leaflets reflexed downward. Overall a medium sized but trunking genus, Microcycas prefer sun and can tolerate light frosts.

Stangeria
This genus of cycads is from coastal South Africa and have a unique fern-like appearance. This is a monotypic genus with only one species. Quite rare to cultivation, plants tend to be small and decorative. Leaves are small with slightly irregular green leaflets. Plants have a tropical appearance and are generally grown in filtered light. There is felt to be two varieties of the species Stangeria eriopus.

Zamia
Zamias are a new world genus of cycads with a distribution from far southeastern United States through Mexico, The Caribbean, Central and South America as far south as Bolivia. There are approximately sixty species with nomenclature still being worked out. Some species like Zamia furfuracea are able to tolerate full sun and are quite cold hardy. Others, like Zamia cremnophila are tropical appearing and more cold sensitive. The true Zamia skinneri from Panama has huge leaflets that can be eight inches wide and twice as long. These are truly gorgeous plants and one of the most exotic cycads on this planet. More than any other genus of cycads, care must be taken in selecting the right plant for the garden. This is because of the specific needs of many species. A few of the more common species are quite available commercially, whereas some species are near impossible to obtain. Many require a greenhouse environment.

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