Introduction to Cycads, the ultimate Jurassic landscape and/or potted plantsBy Geoff Stein (palmbob)
August 27, 2009
(Editor's Note: This article was originally published on March 18, 2007)
What is a cycad?
The most common cycad, and the one most people have heard of, is the Sago Palm. Cycas revoluta is NOT a palm despite what its common name suggests, but is a classic cycad, with it’s palm-like trunk and simple, pinnate leaves. Cycads are non-flowering plants that are actually more closely related to conifers than to palms or any other flowering plants. They reproduce by making cones and seeds. All cycads are dioecious, which means they are either male or female, and never both.
Cycas revoluta, or the 'Sago Palm'
As mentioned above, cycads are typically ‘palm-shaped’: symmetrical plants with fronds arising from the tops of their stems (also called a caudex, trunk or base), similar to how palms or many ferns grow. The frond, or leaf, is made up of a petiole, which arises from the stem and has no leaflets on it, a rachis, which is what the petiole is called further from the stem where the leaflets come off either side (like a palm or fern leaf) and, of course, the leaflets themselves, which are the ‘leaf-shaped’ parts that come off either side of the rachis (with remarkable regularity in cycads). A petiole or rachis is unbranched in all but a few cycads- they have simple pinnate (‘feather-shaped’) leaves. These leaves/fronds are typically somewhat ‘plastic’ or leathery in consistency, which is one of the characteristics that makes cycads unique. These leaves come in various shades of green to blue-green and some are even a pale blue. Some have smooth, simple, spineless leaflets, while some are known for their incredibly sharp, multispined, twisted leaflets. Some cycads can be quite hazardous to handle for this reason.
Encephalartos ferox, horridus and latifrons leaves showing dangerously sharp ends (second photo by tfromky)
Initially a cycad starts as a germinated seed, with one leaf. Then, as it ages, it will grow another leaf every so often… for most species, this is an agonizingly slow process, with many species only making one leaf a year for a while. Eventually, however, two leaves will come up at a time, and finally new leaves will come out all once in larger and larger numbers called a ‘flush’. Some cycads, such as Macrozamias, however, continue to grow one leaf at a time, with just the interval between leaves getting shorter with age.
Dioon spinulosum on left showing typical flush of leaves for most cycad species (many leaves simultaneously) while Macrozamia moorei on right contiuously puts out a leaf at a time
As a cycad ages, it gets taller from the top of the stem. As is also the case with palms or tree ferns, once a cycad has matured to a certain thickness, it will not get any thicker with age, and all growth is directed either up, or into new suckers/pups that arise from ether the root stock, or along the caudex itself. All the energy of the plant is in this caudex (and sometimes the roots), so this is the business part of the plant. Cycads are basically caudiciform succulents. Leaves, and sometimes roots, are expendable. Cutting all the leaves off a cycad rarely affects it in a negative way. But damage the caudex and the plant is often lost.
Adult cycads vary in size and shape depending on the species, with some growing to over 60’ tall, others developing numerous branches and take up many yards in all directions, to very small, even subterranean plants that would get lost in all but the smallest landscape areas or pots.
The Macrozamia polymorpha on the left has a subterranean caudex (lifted up a bit in this pot for effect) while the Cycas circinalis on the right is about 25' tall
Cycads have various root types- some have huge, succulent roots- these varieties usually live in very arid climates. In many of these plants, the caudex itself is also underground and only the leaves are visible except in very old plants. Most cycads have one large carrot-like root, and smaller, more ‘normal’ roots. In all but itty bitty seedlings, most of the ancillary roots can be removed, and if not placed in too-moist or poorly draining soils, the roots will heal over and new roots will usually develop (this is less of a reliable outcome than with the removing of leaves, and is not recommended unless there is some need to do so). Damaging the large, carrot-like root badly, however, is often fatal unless great care is taken to heal the wound and get the plant to reroot in a special medium (eg. pumice). Getting cycads to reroot, or rooting the cuttings/pups off adults, is somewhat of an art, and may require a greenhouse along with keeping the plant in pumice or perlite. Rerooting can take up to several years in some species. There is another kind of root that is somewhat unique to cycads- the collaroid roots, which exist just above or below the surface of established plants, and whose function is to help fix nitrogen via bacteria living in those roots. A cycad with a lot of these collaroid roots is usually a well established and ‘happy’ plant.
Where are cycads from?
Cycads live in nature all over the tropical world, from Central and South America, to Africa, Asia and Australia. A few Zamias are native the ‘tropical US’. No cycads are from colder areas of the world, though some Asian species do live in relatively cool environments. In many of their native lands, some species are extremely endangered and, in a few cases, already extinct. Collecting cycads from the wild is something that is not only frowned upon these days, but is usually unlawful and closely regulated. Saying that, it still happens, thanks to the huge amounts of money some of these plants go for, so probably many of the species that exist today will be extinct in the near future.
How does one take care of a cycad?
Not all cycads need the same care, but in general, most are NOT fond very cold climates, with only a few taking freezing temps at all. One of the reasons Sago Palms are such popular cycads is they tolerate a moderate degree of frost/ freezing climates, but even these have their limits. Cycads are succulents basically and many can be grown similarly to how one grows most succulents. Most tolerate some dryness and appreciate being grown in very well draining soil- most do not tolerate being grown in clay or other poorly draining soils. Of all the genera, Encephalartos species are the easiest to rot from over watering. In general, Ceratozamia, Zamia, Lepidozamia, Cycas and Bowenia are more difficult to over water. Some Macrozamias are water hogs, while most are not and will rot with excessive water. If in a warm climate with the proper soil, most cycads prefer to be watered regularly, and though many are drought tolerant, they tend to perform much better and grow faster if given water often and fertilized regularly as well. Some of the more tropical, rainforest species do NOT tolerate drought conditions, and letting them dry out too long can kill them. Plants grown in pots obviously need to be watered regularly as well, but probably need fertilizing less often than those in the ground.
Planting or transplanting cycads is relatively easy. Root damage will usually occur, as cycad roots are not that sturdy. However, care should be taken not to damage the main, carrot-like root(s) too badly, as injury to this root will allow fungal infections to develop, and sometimes overtake the plant. Still, if this root is badly damaged, often the plant will survive, but will need to be kept dry (do not replant immediately) until the injury ‘cures’ over. Rooting hormone and/or antifungal powders/creams on these injuries can be beneficial. It is best not to water a cycad after transplanting it, as that will also allow fungus and opportunity to invade. Best to wait a week or so (less for very small plants of course) to allow root damage to heal and roots to be able to uptake water again.
Recently dug up Cycas taitungensis, ready to be planted
Most cycads like sun, though some species/genera are not that tolerant of full sun in very hot climates. But lack of any sunlight is usually a problem for cycad health, and most species will not do well as indoor plants. Some require full sun or will struggle and decline. If grown in too much sun, most species will survive, but not look good, with their leaves burning and being stunted. See below for the sun requirement generalizations for each genus.
Cycads need to be trimmed as the older, senescent leaves die. This can be hazardous if you have a spiny species, so use gloves as/if needed. If for some reason the leaves are damaged, but not dead, they still can be cut off without damage to the plant itself. If you trim a living leaf, which is OK if need be, a clearish ‘goo’ may ooze from the cut end. This is the cycads way of curing itself- sort of like a built in liquid bandage system. Seeing this ooze arise from the caudex is not usually a good sign- it indicates there is some damage of the caudex at that site, or deeper within (trauma, insect damage etc.). But do not clean it off- most cycads can heal their wounds well. Just look for the inciting cause if possible.
Some cycads are prone to nutritional deficiencies- this Cycas sp. is suffering from a calcium deficiency
Insect damage is pretty rare on cycads in the US, though Cycas species have been defoliated and/or killed in some the more tropical states by scale. Cycads tend to handle being sprayed with pesticides fairly well. However, see some discussions in Davesgarden about treating scale on Cycas species as that is an exceptional situation.
Scale on Cycas revoluta
One of the reasons cycads are such popular collector plants is they are slow growing. Most can live your entire life in a pot, though almost all will grow faster and better in the ground. Many species will make 1-3 leaf flushes a year… some less often, some more. But very little height is gained in a single new set of leaves, so overall height is a very slowly increasing situation. This makes all but the oldest, hugest plants manageable for the average collector to keep and maintain. With proper care many cycads can live for many hundreds of years… some very old plants in the wild may be thousands of years old. Dying of old age is something much more likely to happen to the grower than to the plant itself.
There are basically two ways to make more cycads- seed germination or removing offsets from the adult plant. Fertilized seeds tend to germinate reliably and easily with bottom heat and humidity for most species but some require specialized conditions (see a cycad text for details). However, since cycads are dioecious, getting fertile seed is NOT as routine as in many other plants. You need both a male and female plant (or pollen from a male plant if you have only the female). Unfortunately there is no way to tell what sex a plant is until it produces a cone- something that can take several decades or longer in many species. Most cycads are from other areas of the world and the insects that pollinate them are not here in the US. So we must become the pollinators! See a cycad text for details on this as this can be a tricky procedure requiring patience and care.
Ceratozamia female cone, and Dioon holmgrenii female plant/cone with male cone laid next to it for comparison
Encephalartos villosus female cone, Encephalartos arenarius male cones, and Enecphalartos arenarius female plant/cone with male cone laid on top
two photos of female Encephalartos ferox and an Encephalatos whitelocki female cone
Lepidozamia female cone, and two Macrozamia female cones
Stangeria female cone, and 1 male Zamia cone next to 3 female Zamia cones
Female Cycas revoluta cones- the one on the right has opened up (was unfertile)
male Cycas rumphii cone
Removing offsets successfully is routine in some species, and nearly impossible in others. Unfortunately it always seems be the expensive, rare species that don’t offset well. Cycas revoluta, the Sago Palm, is an easy plant to grow from offsets, and it also is one of the easier species to pollinate as well. See discussion above about rerooting cycads.
This is a very old and suckering Encephalartos cycadifolia, one of the trickiest plants to grow from offsets
What are the different kinds of cycads?
There are 11 genera of cycads and most are commonly grown and make excellent landscape or potted plants.
Bowenia is an Australian genera that is NOT one of the more commonly grown ones, at least here in the US, as it is fairly tropical in its needs, and can be difficult plants. It is the only genus that produces bipinnate leaves, or leaves that divide/branch. There are two, maybe three species in this genus and they are known for their plastic-like ‘ordinary’ leaflets- simple, thin, ovoid leaves with either smooth or slightly serrated edges.
Bowenia serrulata on left and Bowenia spectabilis on right
Ceratozamia is a Central American genus- there are approximately 16 or more species in this genus, and the number of species changes every 3-5 years as new ones are discovered in the Mexican and Central American jungles. These tend to be fairly large plants, up to 10’ in diameter from leaf tip to leaf tip, and some can have caudeces like small trees. But in generally most or ‘landscape’ size and easy to grow in warmer climates where there is some shade or protection (most are not full sun-loving species). They add a nice tropical, lush look to the garden. Most have leaflets that are large and ovoid or lancelote in shape- no spiny ones in this genus.
Ceratozamias hildae, kuesteriana and latifolia
the common Ceratozamia mexicana, Ceratozami macrostobilis and Ceratozamia miqueliana. The first two are showing a new flush of leaves (red-brown)- they will eventually harden and turn green
Ceratozamia norstogii, robusta and whitelockiana
There is a lot of active study in this genus as many plants are being discovered and some in cultivation still have not been given proper names. The plant on the left is still called Ceratozamia 'El Mirador' while the one of the right is a newly described species, Cerartozamia zoquorum
Chigua is a very rare and nearly impossible to find genus from Colombia. Two species, both look like Zamias, and are both nearly extinct in the wild. Chances are good you will never see one of these plants.
Cycas is easily the largest genus that is from mostly Asia and Australia, but at least one species is also native to Africa. There are about 90 species in this genus, but this is also one that changes its numbers from year to year as new plants are discovered, or old ones are lumped together. This is the genus the common Sago Palm is in. These tend, in general, to have lots of closely spaced, long, thin leaflets each with a prominent central vein. Many people think most of these look alike, so only a few are commonly used in landscaping or pot culture. Sago Palms are used so commonly not only because they are cheap and common, but because they are one of the most hardy cycads, handling an impressive range of temperatures, sun/shade and humidity conditions. No other cycad is this versatile. Another common species is Cycas circinalis, sometimes called a king or queen sago palm. These make great potted or garden plants as they grow fast and have long, soft, somewhat drooping leaves with slight drooping long, thin leaflets- a very graceful and tropical looking plant. Some other species of Cycas also make great landscape plants, though, and are different looking, having either bluish leaves, or extremely fine leaflets, or growing to impressive heights (many can grow over 20’ tall… though they may take many decades to get that tall). In general, the Australian species are more sun and drought tolerant, while the Asian species are more shade and moisture loving, and with a few exceptions, can be quite cold sensitive.
Cycas cairnsiana, media and guizhouensis
Cycas ophiolytica, panzhihuaensis and pectinata
Cycas circinalis, Cycas siamensis in habitat (Thailand) and Cycas platyphylla
Cycas taitungensis, from Taiwan, and Cycas taiwaniensis, NOT from Taiwan (sometimes names are misleading)
Cycas tansachana, Cycas thoursii and Cycas wadei
3 of the 'forked' leaf species: Cycas multipinatta, Cycas daeboensis and Cycas micholitzii
close up of Cycas micholitzii leaf showing the characteristic center rib found in all Cycas species. The second photo shows typical new flush of leaves on Cycas revoluta
Dioon is another Central American genus with about 12 species. These plants typically have very stiff, thin, sharp-tipped, flat leaflets, some smooth-edged, some serrarted, and don’t tend to be very tall plants (D spinulosum is a notable exception). Probably the third to fifth most common cycads in cultivation belong to this genus: Dioon edule and Dioon spinulosum. Both are quite easy to grow and are relatively fast growing for cycads. Most Dioons are from Mexico where they live in dry conditions, though a few are more tropical. Some of bluish, ornamental leaves that make excellent additions to southwest style gardens. All species need sunny conditions to do well, though the wider leaf species will tolerate more shade.
large group of Dioon purpusiis, a common female Dioon edule with an old cone, and a newly forming one, and a female Dioon merolae in cone
two photos of Dioon meijae, and a Dioon califanoi
Dioon spinulosums (first photo with large male cone)
Encephalartos is an African genus, with most being from South and Southeast Africa, with the rest being from Central Africa. These are THE cycads to most collectors of this family. There are a little over 60 species in this genus. They are truly beautiful plants, and make stunning landscape as well as potted specimens. These plants are fairly slow-growing and come a in a wide variety of sizes, shapes and colors. Some are quite massive plants, while others stay fairly small (2’-3’ tall). Some have green leaves while others have blue, to white to turquoise leaves in a variety of leaflet shapes and sizes. Some of the thorniest, most dangerous plants are in this genus, while others are harmless, smooth-leaved species. These plants, in general, are sun lovers and do best grown in hot climates in full sun, with a few exceptions. Also with a few exceptions, all are relatively rare and pricey- some extinct in the wild, or nearly so. Some are incredibly rare and expensive plants- these are the plants most likely to be smuggled or stolen.
Encephalartos altensteinii or left and similar species, Encephalarots natalensis or right... two of the most commonly available species
Encephalartos arenarius, Encephalartos caffer in a pot, and group of Encephalartos ferox
3 of the most popular 'blue species': Encephalartos eugene-maraisii, Encephalartos lehmanii and Encephalartos princeps
3 species with 'atypical' leaflet shapes: Encephalartos friderichi-guilielmi, Encephalartos heenani (a super rare species) and Encephalartos inopinus (another rare one)
Lepidozamia is a genus of Australian plants with only two species in it. Both are relatively tall for cycads (L hopei can grow up to 60’ tall), and have long, smooth, harmless lancelote leaves. These are relatively fast growing and easy to take care of, and do not tend to be very costly unless quite old and large.
Lepidozamia peroffskiana on the left and Lepidozamia hopei on the right
Macrozamia is another Australian genus with quite a lot of species in it (just under 40)… these plants, in general, are smallish (4-5 huge species, though) with predominantly underground stems, and have very thin, to needle-like leaflets, usually smooth and quite stiff and plastic-like. The most commonly grown species are some of the larger ones- these are the ‘girthiest’ of all the cycads and can be up to 3’ in diameter. Most of the smaller species are rare and so slow growing that most enthusiasts don’t bother with them.. most collectors don’t consider a lot of these plants to be highly ornamental, either, but that is obviously a matter of taste. They still make great potted plants, and some do nicely in the garden (just tend to get lost in the landscape sometimes). The few really large species can become spectacular plants, resembling large palms.. but they take many many decades to get that large. In general, these are quite cold hardy plants, and rarely appreciate lots of water. All the large ones are demanding of full sun, though the smaller ones are much less picky about that.
Macrozamia communis of left, the rare and beautiful blue-leaved Macrozamia macdonaldii in the middle, and a Macrozamia dyeri on the right
Macrozamias johnsonii on left and two photos of Macrozamia moorei, one in cone, and one large older trunking plant
3 examples of the smaller Parazamia forms of the Macrozamia genus, from left to right: Macrozamia glaucophylla, Macrozamia stenomera (blue form) and Macrozamia flexusoa
Microcycas is a monotypic genus from Cuba. These plants look a lot like miniature palms and have very tropical requirements. Because of that, and the fact they are critically endangered, these are quite rare in collections and most likely you will not come across one unless you visit Florida or a tropical Caribbean country.
Microcycas plant in Hawaii
Stangeria is another monotypic genus of some unusual low-growing plants from Africa, which are known for their ‘non-cycad’ looks. They have relatively thin, large, sometimes papery leaflets and their caudex tends to be subterranean. The main clue that they are cycads are their reproductive structures- the cones. These are not that rare or difficult to grow, but are slow and not all that spectacular, so many collections will not have one of these in them.
the two forms of Stangeria (same species) in California
Zamia is the last genus, and is one of the largest and least well understood. This is because these plants are not only hard to find in the wild (live deep in the jungles of central and south America) but most are quite tropical in their needs, so less attractive to cycad enthusiasts in more temperate climates. However, one of the most commonly grown cycads, Zamia furfuracea (also known as the Cardboard Palm) is in this genus and is grown as a landscape plant throughout the warmer areas of the US and throughout the world. Most of the other species are more difficult plants and difficult to find as well. In general, these are more shade-loving plants, with Z furfuracea being one of the exceptions.
2 very different species of Zamia: Zamia angustifolia on the left and Zamia fairchildiana on the right
two of the rarer and sought after species, Zamia pseudoparasitica, a true epiphytic species, and Zamia skinneri, one of the larger leaved plants- both fairly tropical
two very common species of Zamia- Zamia furfuracea on the left, and another staged, potted plant, with Zamia integrifolia, or Coontie, a Florida native, on the right
these are two commonly mixed up species- the common plant on the left is Zamia vasquezii, but often incorrectly called Zamia fischeri, while the plant on the right is the true Zamia fischeri, a very rare plant in cultivation
Cycads are, in general, toxic, inedible plants. However, many have historically been used for food by native peoples, who know either what the safe parts of the plants are, or how to properly prepare them. It is best to just assume all parts are toxic, and to keep that in mind when you have pets and/or small children. Though most pets will not eat a cycad, some dogs will eat the leaves or fruits and some species are deadly toxic. And cattle will happily graze on some cycads and succumb to their toxic properties as well. Please keep this in mind when selecting what species to get and where to plant them.
Additionally, as mentioned above, many have very sharp leaflets. Some rival cacti and other spiny succulents in their injury potential, so handling these species may require special gloves or clothing. This is something to keep in mind, also, when planting these in the landscape, since, as they grow, the leaves may extend out into pathways and develop into hazards.
Obtaining cycads and Conservation
Most cycad species are not available anywhere but from growers specializing in the raising, importing and selling of these species. Some species are simply unavailable, which, of course, makes them ‘holy grails’ that some will go any lengths to obtain to complete their collections. Rare and large plants are worth a lot of money to right buyers, with some plants being worth many many thousands of dollars. Collecting for rarities, and the cost of these plants are the driving forces behind the illegal collecting and importing of these plants. Some plants have literally been collected to extinction and many others are on their way. Governments have gotten involved in the protection of many species, making them all that much harder to obtain. However, this has mostly resulted in the inability of the average collector to get certain plants, while the wealthiest and most devious collectors just find these impediments a challenge, often easily overcome.
Cycas siamensis, dug up by farmers illegally, for sale at Bangkok market- only a few dollars each
Many cycad nurseries now are extensively growing their own plants from seed and this practice has finally led to some rare plants being more available, and less costly. Many native countries are also growing their own cycads in nurseries, to help alleviate collections pressures as well as for generating income. But this it a slow process as cycads, even in their native countries, are very slow growers, and only larger plants are worth enough money to make the whole process financially feasible. So government support is a necessity in many cases (and absent, in many, too, so it’s hit and miss right now).
Cycad nursery in the US
Please, if you are getting a cycad, try to find out where it came from. Do NOT get illegal plants! Any large, rare plant who’s source is not known, could potentially be an illegally obtained plant, and