Cycads in my home garden, July 2016

Growing cycads is a labor of love that takes a lot of patience, and failure is common. That is particularly true if try to grow species from around the world since they have a wide range of needs and tolerances. In my home garden here in southern Japan I grow species from the Americas, Africa, Australia and Asia. My success has been, not surprisingly, variable. I grow all of my collection in pots since my garden is quite small and I rent the house.

Here’s what’s going on in my cycad collection this summer, 2016.

Lepidozamia peroffskyana (right foreground), Encephalartos ferox (center), Dioon spinulosum (left back), and Zamia dressleri (pink flushed plant) – all of these plants have flushed new leaves this season except E. ferox. When growing cycads you get used to plants skipping a season for new frond growth.
Dioon spinulosum and Zamia dressleri – both plants have newly flushed growth. The Dioon has a lovely soft blue green color and the Zamia pink-bronze. Both will harden off and mature to dark green.
Zamia dressleri – his species has been really hard to keep here in southern Japan, mostly because of the colder winter conditions, even in the relative warmth of a grow room which occasionally goes down to 5 C – not to its liking. It is said this species also needs a particular mycorrhizal fungus to remain healthy long term. I can only guess this plant was inoculated with the fungus when I got it five years ago.

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The windmill palm, Trachycarpus fortunei, king of the cold hardy palms

The windmill palm, Trachycarpus fortunei, is the most cold hardy of the arborescent palms found anywhere in the world – at least as far as we know. Originating from central China and adjacent parts of southeast Asia, it is grown in far flung parts of the world these days, withstanding surprising amounts of cold, wintry weather. If you’ve seen a picture of a palm tree with snow covering it, most likely it was a T. fortunei.

It has become such a common feature in “tropicalesque” temperate gardens that having one is no longer a big deal nowadays. In nature it lives in humid continental climates that range from cool to hot in summer, and quite frosty in winter. For this reason it can be grown in both hot and cool summer areas, provided winter lows don’t get too cold.

Trachycarpus fortunei pair
Trachycarpus fortunei, the windmill palm, is the most cold hardy of all arborescent palm trees.

Trachycarpus fortunei is a single stemmed, arborescent palm of relatively cool mountain forests. The trunk typically attains heights up to 10 meters (~30 feet), however vigorous ones can go 13 meters or more (a little over 40 feet). It’s trunk is quite narrow, no more than 30 centimeters in diameter, and usually covered by a thick layer of old leaf bases that look exactly like a fibrous plant husk. Some older trees have clear trunks that are grey in color.

The fronds are palmate, meaning they have a long leaf stem (petiole) that ends in a fan-like frond composed of fused leaflets. These grow up to 2 meters long, are very regular in appearance, are normally dark green, and very nearly round, hence the common name windmill palm. The petioles are nearly bare except for a two rows of small spines, and can be up to a meter long. The fan is composed of 30 to 50 leaflets, each up to 90 cm long. They can be held straight out in some trees, forming a true fan shape, or droop considerably in others (much like the leaflets of Livistona chinesis). These characteristics are consistent within a tree, and so are due to genetic rather than environmental factors.

Windmill palm trunk
The trunk of the windmill palm is literally covered by fibrous old leaf bases. These have been used in Asia as a material for fabrics.

Flowering commences in mid spring. Clusters of flowers (called spadices) emerge and elongate into downward arcing scapes up to a meter long and carry hundreds of flowers each. This palm is dioecious, meaning trees either carry female or male flowers. Flower color is creamy yellow, though the female flowers are bit more green. Male trees can also have spadices that have hermaphroditic flowers (having both female and male parts) and these can set viable seed. The kidney shaped seeds mature to a blue-black color by late fall and winter.
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Pindo palm, Butia capitata, AKA the jelly palm

The genus Butia, the so called pindo palms, are native to the grasslands of southern Brazil into Uruguay, Paraguay, and Argentina. They also are known as jelly palms since their large yellow-orange fruits can be used to make reasonably good tasting jams. They have the added benefit of being some of the more cold tolerant palm trees, taking several degrees of frost before showing signs of distress.

Perhaps the most celebrated of the genus is B. capitata, a palm that has a long history of cultivation in western gardens. This species is a pinnate palm, often called “feather palms”, since their fronds are long feather-like affairs with a central leaf axis (known as the rachis) supporting rows of long, simple leaflets (known as pinnae) extending down its length. As with many commonly grown plants however, its story is quite a bit more complicated than what one would first imagine.

Pindo Palm tree
Pindo palms have a very distinctive look due to their highly recurved, blue-grey fronds. This large specimen is growing next to a public building in Sasaguri Town in Fukuoka Prefecture, Kyushu, Japan.

The pindo palm typically grows between 3.5-4.5 meters tall, but can reach 6 meters or more in vigorous specimens. Its trunk is singular and thick, typically between 30-50 centimeters in girth, and very often covered with old petiole bases (leaf stalks) that can persist for years. Clear trunks are grey in color and patterned with old leaf scars, giving it a horizontally banded look.

The fronds are pinnate in form, growing between 1.5 and 3 meters long, and arch in a recurved shape back towards the trunk, giving this palm it’s signature look. Their overall color is commonly blue-grey, but can be light green depending on environmental and genetic factors. The rachis supports opposing rows of regularly arranged pinnae up to 75 cm long each, the longest being mid-frond, and held in a pronounced “v” shape. The petioles are armed with abundant, long teeth, as can be seen in the persistent leaf stalks. Plants grown in poor soils or more sun tend to be more compact than average specimens.

Flowering normally commences in late spring to early summer. The yellow-cream flowers grow in large, stalked bundles which can be up to a meter long with many side branches. The ovate to rounded, brilliant orange fruits are borne generously in tight clusters from late summer into fall. They average between 2-3 cm across.

The “true” Butia capitata is native to a very confined area in the coastal states of Bahia and Minas Gerais in central Brazil. Now for that aforementioned complexity about this palm. Apparently most of them cultivated around the world are NOT B. capitata, but rather are a different species, the most probable candidate being the recently named B. odorata, a native of the coastal areas of Uruguay and the adjacent state of Brazil, Rio Grande do Sul. To complicate matters more, several species of Butia from the surrounding region, notably B. eriospatha (confined to southern Brazil), B. paraguayensis (a dwarf widespread species), and B. yatay (a taller growing palm with a thicker trunk) are being grown as well. Butia species readily hybridize, so it is also possible that the great range of variation seen in cultivated plants is in fact an artifact of interbreeding. Go figure.

Pindo palm frond
The fronds of pindo palms are composed of opposing pairs of long leaflets known as pinnae arranged along a central leaf stem. This appearance has given this type of palm the common name, “feather palms”. Butia species are one of the most cold hardy of this group.

All Butia species are native to grasslands and dry open forests ranging from southeastern Brazil, into Uruguay, Paraguay, and northeastern Argentina from near sea level to over 1000 meters elevation. They can be found in the Cerrado region of Brazil (an area comprised of various types of savanna where woody species are plentiful), sandy-soil grasslands, pasturelands, the restingias ecoregion (dry coastal forests of the Atlantic coast) and campos (grassy plains with few trees). Species growing in the inland/upland areas are subject to fairly severe frosts with little protection, and so can be assumed to be far more cold tolerant than coastal populations.

If it is true that most pindo palms in cultivation are derived from B. odorata stock, a species found only in the restingias of coastal Uruguay and Brazil, one would expect these plants to be rather frost tender. Remarkably however, most sources consider typical plants in the trade to be cold hardy to at least -10 C (14 F) without any winter protection. With some protective measures, plants have been grown in far colder climates, apparently being rather commonly seen on the eastern coastal plain of the USA as far north as North Carolina with outlying specimens being grown even up to Washington, D.C., New Jersey and Long Island, in New York State.
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Phoenix canariensis, the Canary Island date palm

Surly the largest commonly grown ornamental palm in the world is the Canary Island date palm, Phoenix canariensis. A close relative of the true date palm, P. dactylifera, this species is much more widely grown due to its ability to live in a broad range of climates and soils. Beyond that, this palm is truly stunning as a mature tree.

Phoenix canariensis is a massive palm with a single trunk growing typically up to 20 meters, but vigorous specimens have reached twice that height. The thick trunk is up to nearly a meter across with a wide, bulbous flaring base. It is prominently marked with petiole scars that have a stacked appearance, and is usually light brown in color.

Canary Island date palm tree
A mature specimen of the Canary Island date palm is truly an impressive tree. This one is growing on the island of Kyushu, Japan.

The fronds are pinnate, growing from 4 to 6 meters in length on mature trees. The individual leaflets (called pinnae) are simple and narrow, between 20-40 centimeters long each. The central shaft of the frond, the rachis, widens at its base and is armed with long, sharp spines. The overall appearance of the fronds is like a long feather. A mature specimen can hold a hundred or more fronds at one time, forming a dense, nearly rounded crown up to 10 or more meters across. Like other palms the petiole bases can persist for some time, an attribute particularly noticeable on pruned specimens.

Flowering starts in early spring. The bright orange branched flower scapes are born abundantly, but remain tucked within the the crown even in at full maturity. These palms are dioecious, meaning male and female flowers are found on separate trees. Fruits are ripe by fall or early winter, and though fairly large, are not particularly fleshy, and so do not make a good date for eating. A single large seed is contained in each fruit.

P. canariensis is an endemic of the Canary Islands, a volcanic island chain off the southwest coast of Morocco in the Atlantic Ocean, and though owned by Spain, are largely self governed. This palm is found throughout the main islands, however its distribution is scattered and localized due to centuries of human activity. The largest remaining populations are found on La Gomera. The introduction of exotic Phoenix species (especially P. dactylifera) has put the remaining populations at risk since these palms easily interbreed, creating hybrid trees that can be difficult to distinguish from wild ones.

They can be found in a wide range of habitats, typically in dry subxeric Mediterranean areas and more rarely in wet cloud forests, known locally as laurisilva, consisting of broadleaf subtropical evergreen trees. In some areas P. canariensis is the dominant species, and these communities are known as palmerales. Nowadays these once natural associations are highly influenced by humans who have introduced exotic species or expanded them by planting more palms. This species grows from sea level to around 600 meters elevation in its native habitats. For more about this palm in its native habitat please read this fascinating article from the journal of the International Palm Society: Phoenix canariensis in the wild.

Canary Island date palm trunk
The trunk of the Canary Island date palm has prominent petiole scars “stacked” on top of each other.

In of spite being from the relatively low elevations of subtropical islands, the Canary Island date palm is remarkably cold hardy. Most sources state large trees can take -10 C (14 F) for brief periods and rebound, though fronds are damaged at much higher temperatures, taking no more than a couple degrees of frost before die-back begins. Nevertheless, consistent reports of them surviving in USDA cold hardiness zone 8 persist, at least in areas where summers are hot. Having said that, as long as the average temperate remains a few degrees above freezing in winter, this species seems to hold on. Reports of specimens growing in cold weather latitudes also abound, for instance the warmest parts of the British Isles (including London), Tasmania, and even the coastal areas of British Columbia, Canada and along the coasts of Washington and Oregon in the US if given protection in winter. On the other hand, it is able to live in truly tropical places as well, making it one of the most temperature resistant palms in cultivation.
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The Mexican fan palm, Washingtonia robusta

Washingtonia robusta, the Mexican fan palm, is perhaps one of the most commonly planted palm trees around the world, and yet its native home in northern Mexico is limited to a relatively few water canyons scattered here and there in Sonora and Baja California. Rows of it’s dizzyingly tall, slender trunks topped with a relatively small crown of fronds are the icons of southern California’s older neighborhoods – it’s hard to find a photo of Hollywood that doesn’t include at least a few. So how did this relatively scarce palm become so widely grown throughout the world’s warmer climates? The answer is simple – this is a very tolerant, fast growing palm.

Washingtonia robusta group
A fairly tall group of Washingtonia robusta growing at Kyushu University's Campus in Fukuoka, Japan.

Washingtonia robusta is a denizen of water canyons in otherwise desert to semidesert regions. It is one of the tallest palms in the world, commonly topping 15 meters, with exceptional specimens growing an additional 10-15 meters higher. Its unbranched gray trunk is generally quite slender, usually not more than 30 centimeters in diameter, but swells considerably at the base. It is ringed by close set leaf scars and in tall trees tends to curve a bit as it ascends in long, lazy arcs.

The glossy fronds are palmate in form, are rich green in color, and have hanging leaflet tips not unlike Livistonia chinensis, though not as pronounced. The fronds are quite large, a bit longer than wide, with mature fronds growing up to 1.5 meters long. They form a large round crown, and tend to remain attached to the trunk even after they die, creating the tell-tale skirt common to this genus. The petioles grow up to a meter long and are host to rows of large orange hook-shaped sawtooth spines.

In spring and early summer long sprays of tiny white flowers are produced on hanging branched flower stalks that grow beyond the limit of the crown, each extending up to 3 meters in length. By the fall thousands of small dark brown fruits are produced on them, making this palm a potential weed in the right climate.

The Mexican fan palm is found in nature in seaside facing water canyons and oases near the coast of Sonora (generally north of Guaymas) as well as Baja California. Its range is by no means continuous, but rather highly scattered, suggesting a remnant distribution from a time when conditions allowed it to be more widespread. Its northern distribution is close to its sister species, Washingtonia filifera, but apparently they never are found growing naturally together.

Mexican fan palm crown
The crown of the Mexican fan palm is slightly taller than wide. This tree has been trimmed of its dead fronds, hence it is lacking the "skirt" of unpruned trees. The flower stalks however were not trimmed this season, so you can see the bunches of dangling brown fruits ready to fall and germinate in droves or be eaten and dispersed by birds.

In spite of its rather restricted native distribution, this palm is far from rare these days, in fact in many places it is considered a potential pest. In parts of central and southern California it has naturalized itself such that the California Invasive Plant Council considers its impact on native ecosystems a “moderate risk”. Many people who have grown this palm and let it go to seed have found out just how easily it spreads, sometimes forming “lawns” of seedlings. It is not uncommon to see young trees growing literally in the cracks of concrete walls and sidewalks.
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The Chinese fan palm, Livistona chinensis

Livistona chinensis is one of the more cold hardy palm trees commonly in cultivation, and yet ironically is native to the essentially frost free subtropical islands and coastlines of China, Taiwan, and southern Japan. This palm is better known by its common names, the Chinese fan palm and the fountain palm. The former name comes from its palmate leaf structure, while the latter is due to the frond’s hanging apical lobes that create a falling, fountain-like appearance. Without a doubt, this palm is the most commonly grown Livistona species in the world, and given its beauty and cold-hardiness, it deserves a closer look.

Livistona chinensis palms
Livistona chinensis or Chinese fan palm makes a lovely landscape specimen.

The Chinese fan palm is a tall trunk forming palm of coastal and island forests amidst warm, subtropical seas, commonly forming monospecific groves. They typically stand no more than 10 meters tall, but large specimens can approach 15 meters. The gray to brown trunk is usually not more than 30 centimeters in diameter and is essentially naked since the petiole stubs tend to fall away quickly once old fronds are shed. The fronds are costapalmate (having long costa extending up the center of the palm-shaped leaf), up to 200 centimeters long, nearly as wide, and can number 50 or more forming a dense crown. The thin, long apical lobes hang perfectly downward giving the crown a pleasing, fountain-like appearance. The petioles are stiff and highly serrated with sharp brown spines, and are 150 -180 centimeters long. The trunk is unbranched and strong, being quite capable of withstanding intense typhoon winds that haunt this tree’s native shores.

This palm is hermaphroditic, bearing both male and female flower parts. The subglobose (nearly spherical) yellow-green flowers are born on relatively short, branched flower stalks in the early summer. These never grow beyond the confines of the crown, and so remain relatively unseen during flowering. The blue-black olive-like fruits range from subglobose to ellipsoid and usually are fully ripe by early winter. Seed production can be copious, making this species a potential weed under the right conditions.

In nature this stately palm is never found far from coastlines, in fact its habitat is restricted to the sandy southern shores and islands of the South China Sea, northward to the East China Sea, and east to the immediately adjacent parts of the Pacific Ocean. Historically it was found from southeastern China (Hong Kong, Hainan Island, and Guangdong Province), Taiwan, many of Japan’s Nansei Islands (Yakushima, Tanegashima, Okinawa, Iriomotejima, and Ishigakijima), northward to the Korean Straight (Okinoshima), along the Pacific coast of Kyushu (Aoshima), a few coastal areas of Kyushu (Cape Sata and Cape Toi) and Shikoku (Ashizuri Peninsula), as well as the Bonin Islands (Ogasawara Islands) in the Pacific Ocean.

Chinese fan palm flowers
The small spherical flowers are borne on short branched stalks that do not exceed the limit of the tree's crown.

It also is native to Uotsurijima of the Pinnacle Islands (called the Senkaku Islands in Japanese and Diaoyu Islands in Chinese) where apparently it forms near continuous stands on much of the island. The fate of this population is uncertain given the hotly contested status of this tiny island chain, but it seems that the non-native goat population poses a more immediate threat for the entire island’s ecosystem. This palm has suffered range restriction due to human activity throughout its native distribution, particularly where it is found on mainland areas.

Despite its relative rarity in the wild, Livistona chinensis has been naturalized in many places throughout the world including Bermuda, Mauritius, La Réunion, Hawaii, southern Florida, New Caledonia, Fiji, Vietnam, and Java. In Florida it has been listed as a category II plant by the Florida Exotic Pest Plant Council – a designation for species that potentially can become an invasive pest. To date it has not been found to be aggressively invasive there, and is even recommended as a yard specimen in the northern half of the state by the University of Florida’s Institute of Food and Agricultural Sciences (IFAS).
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Zamia variegata, the world’s only variegated cycad plant

The low, wet forests of Central America are home to to the only variegated species of cycad in the world, Zamia variegata.  This species is often listed as “small” in size, but don’t be fooled, it can have fronds up to 3 meters long.  Though there are a number of related cycad species, none possess its one unique feature – variegated leaves.

Zamia variegata new growth
The newly forming frond of Zamia variegata is covered in a fine light green and brown pubescence.

Z. variegata (also known as Zamia picta or Z. picta variegata) is an evergreen herb with a relatively small underground stem or caudex.  This is basically round and usually not more than 20 cm across, boasting just a few leaves at any given time.  The fronds are long and their structure is analogous to a once pinnate fern.  The midrib or rachis, as well as the petiole is furnished with many short, yet sharp spines.

The petiole may make up as much as 1/3 of the total frond length, which is typically 1.5 to 2.5 meters long, but may be up to 3 meters in exceptional specimens.  The pinnae, or leaflets, are born in opposite pairs along the midrib and are quite long and broad, 15-35 cm long and 4-9 cm wide.  When mature they are stiff and glossy, a rich green color, and striated with many streaks of irregular yellow-green lines, spots, and patches.  Like many cycad plants, they are serrated.

Initially the new fronds start out as tiny yellow/green growths originating from the crown of the caudex.  Over a period of 5-8 weeks these gain in size and finally mature and harden off.  The young frond is covered in silvery to brownish pubescence, which is eventually shed from the mature frond.  The speed at which this young growth expands and matures into a full grown frond is truly remarkable, as in other cycad species.

Zamia variegata mature frond
Mature fronds of Zamia variegata can be up to 3 meters long and hang in a graceful arc.

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Videos about Cycads

Have a look at these videos anytime you like. This post contains all the videos I have on cycads and will be updated as new videos are produced.

Cycads for the shade garden 1 – Here are some cycads I’m growing in my southern Japanese garden. Sorry about all the ants and the incessant cicada singing! Featured plants include, Ceratozamia robusta, Cycas debaoensis, Cycas revoluta v. alba, Lepidozamia peroffskyana, Zamia dressleri, Zamia elegantissima v. alba (Z. sp. ‘Blanco’), and Zamia imperialis (previously known as the red flushing form of Z. skinneri). Cycas revoluta isn’t necessarily shade loving, but I like to keep seedlings in a more protected place until they get a bit bigger.

Cycads for the shade garden 2 – The second installment of my shade growing cycads. In fact Dioon spinulosum is not necessarily a shade growing plant, but I think they look healthier with at least some shade. Featured plants include Cycas debaoensis, Dioon spinulosum, Zamia pseudoparasitica, and Zamia variegata (AKA Z. picta variegata).

How to repot a cycad – A tutorial for repotting a few Central American cycad species, Ceratozamia robusta, Zamia elegantissima v. alba, and Zamia pseudoparasitica. This step by step video will show you how to repot your precious cycads. Sorry about the mispronunciation of the word, coralloid in the video. These specialized roots of cycads are called this due to their coral-like appearance.

Central American cycads flushing new growth – Summer is time for cycads to flush and here are some Central American species throwing new leaves in my collection. Unfortunately I only get one or two leaves per year out of most species in this climate since their winter quarters are just too cool. All species in the video are true tropical plants. Featured plants include Ceratozamia robusta, Zamia elegantissima v. alba, Zamia imperialis, and Zamia variegata.


Cycas revoluta v. aurea, an odd type of king sago

In the islands around Amami Oshima, just north of Okinawa, Japan, there exists an odd type of Cycas revoluta known in the west as variety aurea.  This is not your typical king sago, nor is it the result of poor growing conditions, bizarre horticultural techniques, or a virus.  It rather is a consequence of a genetic anomaly, as we’ll see in the following picture sequence.

Cycas revoluta v. aurea is a naturally occurring form that boasts an interesting color pattern on its otherwise normal fronds – each pinna is tipped in gold.  These yellow tips are attractive to some while others think it makes the plant look diseased or ill treated.  To my eye, the regular pattern of yellow against the dark green of the inner pinnae is indeed attractive, particularly at a distance.  In Japan it goes by the names kogane sotetsu (gold cycad) and kinbuchi sotetsu (gold rim cycad).  The following is the growth cycle of a plant over the past year here in southern Japan.

In June the plant begins its flush and by early July the new fronds have matured and hardened, but remain a bright green color.  If you look closely, you can see that already the very tips of the pinnae are turning yellow.

Cycas revoluta v. aurea 7/8

By early August the yellowing process is in full swing and the inner segments of the pinnae are now fully mature and taking on the characteristic deep green of this species.

Cycas revoluta v. aurea 8/1

A couple weeks later the yellow has deepened further and the plant is at its best, with little or no browning of the tips yet.

Cycas revoluta v. aurea 8/17

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Cycad plants from around the world, but just a taste

Over the past couple seasons I have found myself collecting a group of plants that have fascinated me for  years:  cycad plants.  Here is a taste of a few I’ve managed to acquire.  Most are immature plants, not much more than large seedlings, but as you will see, they are indeed lovely things.

First off is the native cycad of Japan’s southern islands, Cycas revoluta v. aurea.  This form is fascinating in that the leaf tips are naturally weak, hence within a month of flushing they turn from green to light yellow.  This yellowing spreads down each pinnae throughout the summer and fall.  Some find this lovely, while others might not.  It is a very popular form in Japan and has even found its way into the international market.  All forms of this species are cold hardy to at least USDA zone 8b.

Cyas revoluta aurea frond
Cycas revoluta v. aurea has yellow tipped pinnae.

Next up are all Central American species.  Let’s start with the genus Ceratozamia, in this case Ceratozamia robusta.  This lovely plant flushes bronze-red, but as the fronds age they turn completely green.  Like all members of this genus, C. robusta grows a relatively short trunk, but can sport leaves up to 3 meters long.  It is found from extreme southern Mexico and Guatemala to Belize in lowland tropical forest.  All members of the genus Ceratozamia are listed under CITES Schedule I, and therefore even sending their seed across international borders is highly restricted.  This species cannot endure cold and therefore is limited to USDA cold hardiness zone 9b or higher.

Ceratozamia robusta new frond
Ceratozamia robusta flushes light bronze-brown.

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