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Uncommon Cycads Best Suited for the
Florida Landscape
by Tom Broome, The Cycad Jungle
Abstract. Cycads have survived on this earth for over
250 million years. One reason for this is because they can grow where the faster growing
angiosperms can not survive. They can thrive in sandy soils with no nutrients. Some live
on top of solid rock. Cycads even have a specialized root system, called coralloid roots,
that in essence produce nitrogen for the plant to use. For many reasons cycads are perfect
for xeriscaping projects, and growing in our sandy soils here in Florida. Most of us are
familiar with sagos, cardboard plants, and coonties, commonly used in landscapes. But what
about the other 250 species? Uncommon cycads growing in Florida nurseries are an important
resource that has been untapped by landscapers throughout our state, mainly because people
are not familiar with them. I will discuss five uncommon, but available cycads that are
best suited for the Florida landscape.
Cycads are the oldest living, seed-bearing plants left
on earth. The first fossil cycads date back 250 million years. During the age of the
dinosaurs, cycads were the most prominent plant group. Around 75 million years ago the
flowering plants evolved, and ended up to be the most prevalent plant group today. The few
hundred species of cycads that exist today are a small fraction of the species that used
to exist. The cycads that are left are the ones that can survive where the faster growing
flowering plants cannot. These habitats are usually deserts and other sandy areas, on top
of stone outcroppings, and forest areas too dark for flowering plants to grow well.
Cycads have structural mechanisms that have helped them to survive all
these years. Most have some sort of spines on the leaflets, and cataphylls on the stems to
ward off any animals that may want to eat them. Cycads have a specialized, secondary root
system called coralloid roots that grow up to the surface instead of down like most roots.
A blue green algae grows on top of these roots and helps with a nitrogen fixing process
that, in essence, produces nitrogen for the plant to live on. This is why a cycad can grow
on solid rock without any nutrients. The stems of cycads are also very hardy. Cycad stems
have a starch content of around 65%. If something happens to the foliage or a part of the
stem is damaged, the plant will live off the starch until new leaves or new growing apexes
are produced. In certain habitats, seasonal fires are a way of life. The stems get burned,
and the next year new foliage emerges. Cycad stems can even be propagated by cutting them
up into small pieces and planting them separately.
The ground that landscapers have to work with here in Florida is
usually sand, in most areas, and coral rock, in some of the southern parts of our state.
It is hard to get many of our plants to grow in these areas. Use of native plants and
xeriscaping is increasingly the way of the future for landscapers. Cycads are perfect for
these types of landscapes and soil conditions. Native Zamias are already being
used by municipalities and road departments all over the state in great numbers. Are there
any other cycads that can be used in these cases? There are many cycad species growing in
Florida nurseries that would be perfect for these xeriscape projects as well as in our
everyday landscapes. The main reason that people don't use these unusual cycads in the
landscape is that they are not familiar with them. Lack of supply of these cycads has also
been a determining factor. In the last five years there has been a lot of interest
generated by new books on the subject of cycads and by the many cycad societies that have
been formed all over our state. Supply of unusual cycads in wholesale nurseries all over
Florida has probably tripled in the last five years.
There are several unusual cycad species that can be grown quite
successfully here in Florida, but a good supply of these plants for the landscape trade
might be several years coming. I am going to discuss five species that will work well in
our landscapes, and either already have a widespread availability or will have in the next
few years. These plants will be discussed in the order of the most available to the least
available at this time.
Dioon edule is probably
top on the list for cold hardiness of all the cycads that grow well in Florida. After the
freeze of 1989 my king sagos were totally defoliated. My Dioon edule plants did
not even get tip burn at 17°F. I know of people who have tested this plant down to 10°F.
In habitat, these plants grow in sandy areas, and sometimes on rocks over looking the Gulf
of Mexico, also showing their great salt tolerance. In fact, they will grow well in almost
any kind of soil that drains well. Barring any insect or pathogen damage, these plants
will live for 1500 years with no real care at all (the plant to the right is at least 200
years old). Dioon edule has the general appearance of the king sago, with lighter
green foliage. These plants are available all over the state by wholesale nurseries that
carry other more well-known cycads. |
Cycas taitungensis,
commonly known as the Prince Sago or Emperor Sago, is starting to be widely used in areas
where a larger, but cold hardy cycad is needed. The leaf spread of the King Sago will
normally be around six feet wide, whereas the spread on this species will be around eleven
feet. The foliage has been found to be slightly less frost tolerant compared to the king,
but the stems are known to be more cold hardy. People have been growing these plants as a
test in Atlanta and in central Alabama. These plants are also very salt tolerant. Cycas
taitungensis is probably the fastest growing cycad on earth. If grown in full sun and
fertilized heavily, these plants can push up to six leaf flushes per year. With the right
growing conditions, these plants can grow from a sprouted seed to a plant with a two-foot
tall stem in less than five years. Availability is very good on this species, with more
than 100,000 plants being produced each year in Florida. |
![enceph_ferox_cone2.JPG (37538 bytes)](enceph_ferox_cone2.JPG) Encephalartos ferox
is a species from South Africa that is getting to be the most sought after and unusual
cycad in south Florida. This species has leaflets that resemble the leaves of a Rotunda
Holly plant, making it very showy. The best attribute this species has is the bright red
cones that are produced on the mature plants. A female cone can be fifteen inches tall and
ten inches wide. A larger plant can produce as many as five female cones at one time. With
the dark green foliage, these red cones can really stand out in the landscape. I like to
use these plants with Aztec Grass to add to the contrast of color and texture. Encephalartos
ferox prefers to grow in a semi-shady area to look the best. The plant can tolerate
temperatures down to 18°F, but is not very frost tolerant. If grown in the shade, it
would be protected from these frosts. This species will attain a spread of nine feet in
only eight years of proper growing. Supply of this plant is not meeting the demand yet,
but there are a dozen nurseries in Florida propagating these plants from seed. |
Ceratozamia kuesteriana
is a cycad from Mexico that is just now coming into the scene. The foliage is very frost
tolerant and the stems have proved to be cold hardy down to 17°F. This is a subterranean
species, so if the stem is planted below ground level, it would tolerate a lot lower
temperatures. This is one of only a few species of cycads that are totally unarmed, or in
other words there are no spines on these plants. This species would make a good accent
plant near walkways where most people would not want to use other cycads. Ceratozamia
kuesteriana has what cycad collectors call brown emergent leaves. The new soft leaves
come out brown and then harden up to a light green. This color change can be very
attractive in the landscape where contrast is needed. A single headed plant will attain a
spread of five feet, but multiple heads can be produced to increase the spread to around
seven feet in time. This is another plant that would prefer to be in a somewhat shady
location to look it's best. Several years ago two or three thousand plants were imported
into Florida and there are currently quite a few people with breeding colonies. Somewhere
around 10,000 seeds are produced each year in Florida, but this will have to increase if
demand for this species becomes more popular in the future. |
Ceratozamia hildae,
commonly known as the bamboo cycad, has got to be the most exciting new species of cycad
to enter Florida. This plant grows more in a shape similar to bamboo instead of having a
fountain form like most cycads. The foliage and the stem are very cold hardy, and
have been tested in Louisiana with very good results during the 1989 freeze. Except for
bamboo, there are not too many cold hardy plants that have this upright habit. These
plants can be used in smaller areas where sagos would be out of the question. The leaves
on this species will attain a height of around seven feet, and the leaflets are arranged
in clusters that resemble a bow tie in appearance. Ceratozamia hildae is a fairly
fast growing species and can become mature in only four to five years. This plant looks
it's best in partial shade but can be grown in more sun and in deep shade. This is a plant
that we will have to look for in the future. Around 6,000 seeds are produced each year in
Florida, but in five years this figure will increase to 50,000. When more people realize
how beautiful and versatile these plants are, there will be a great demand for public and
private use. |
Tom Broome
The Cycad Jungle
(941) 984-2739
e-mail: cycadjungl@aol.com
Note: This article was given as an oral presentation (Paper No.
33, Program section: Garden and Landscape) at the Annual Meeting of the Florida State
Horticultural Society, November, 1998, and is used with permission.
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