Cycads - The Plants & Their Cultivation

An introduction to these interesting and ancient plants.
Andrew Shaw, 15 Ancona Rise, Darfield, Barnsley, South Yorkshire, U.K.
Chamaerops No. 6, published online 23-10-2002

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Cycas revoluta: just say go.

The living cycads are a group of primitive tropical and subtropical plants which have changed very little over millions of years. During the Jurassic period (160 million years ago), cycads formed the forests of the world. This has led the species surviving today to become affectionately known as 'living fossils', despite the evidence pointing to them actually evolving comparatively recently. Their closest living relatives are Gingko, the Maidenhair Fern Tree, Gnetum and the curious Welwitschia from the harsh Namib Desert.

Today, botanists recognise four families of cycads in the order Cycadales. The first of these families, the Cycadaceae, contains only those species of the genus Cycas. The Zamiaceae encompass eight genera and represent the largest number of families, namely, Zamia, Ceratozamia, Chigua (described only in 1989), Microcycas, Dioon, Encephalartos, Macrozamia and Lepidozamia. A line of thinking, however, is that Dioon should be 'split off' into a group of its own. The third family, Boweniaceae, comprises only the genus Bowenia from Australia whilst the only member of the last family, Stangeriaceae is Stangeria eriopus from South Africa. In total, these genera contain around 180 species, many of which are classed as rare, vulnerable or are even threatened with extinction in the wild.

Cycads are altogether very attractive plants - many resembling palms in appearance with pinnate leaves and scaly trunks. Thus, they are in heavy demand for landscaping in the warmer parts of the world. In cooler climes however, they make excellent pot plants, certainly a change from the humble Rubber Plant!

Although I am certainly not the last word in cycad cultivation, I would like to describe the way that I grow them, and also the observations I have made, which will hopefully help other growers.

The only real method of propagating cycads available to the amateur, is from seed. In some families, seed will develop regardless of pollination taking place or not. This especially applies to Encephalartos and can cause problems since only seed resulting from pollination will germinate. Apart from cutting seeds open to determine the presence or absence of an embryo (difficult and rendering the seed useless in the process) there is no reliable test for seed viability. The so-called 'water test', where seeds which float when placed in water are deemed unviable, in my opinion, does not work. Several seeds, which I have germinated, floated prior to sowing and indeed some species of cycads actually have seeds designed to float to aid distribution. I tend to assume all seeds to be viable and sow the lot; they're much too valuable to simply throw away without sowing!

The seed itself may arrive from suppliers cleaned or with its fleshy seed coat still intact. If the latter is the case, I soak the seed and then remove the fleshy 'fruit' with a sharp knife. I do this for two reasons: firstly, the seed coat may contain germination inhibitors and secondly, its high sugar content will almost certainly induce fungal contamination. Cleaned seed I have found to be remarkably resistant to fungus.

The cleaned seed is then either scarified (part of the hard seed thinned down) and soaked for 24 hours in tepid water or simply soaked for 48 hours. Both methods seem to yield similar germination results, at least from my trials so far, albeit with small amounts of seed.

After soaking, the next treatment is with an antifungal agent. I have found yellow sulphur to be more effective than proprietary fungicides such as Benlate. All I do is simply dry the seeds with a cloth and then roll them in the sulphur.

Next the sowing. The compost mixture I use consists of four parts peat, two parts of vermiculite and one part of grit sand.

Once mixed thoroughly it is made only SLIGHTLY damp. A handful or so is then placed into a polythene bag and the seed placed on top of this compost, but not fully buried, before the bag is sealed. I find this method better than using a pot of compost since it allows the seeds to be checked for germination more easily.

My preferred temperature for germination is around 28°C in an electric propagator, but an airing cupboard works equally well providing it does not get too hot. I have also germinated seeds at temperatures down to 17°C. Cycad seeds actually begin to develop soon after being shed from the parent plant and so may not germinate for several months after this time.

Seed from commercial sources, if viable, has usually been stored for some time and so may germinate fairly quickly after sowing. The shortest time in which seeds of mine have germinated is 4 days, these being Cycas cairnsiana and Macrozamia lucida. I generally remove germinated seeds from the bags just as the first frond starts to show. They are then potted up into a similar mixture to that used for germination but with extra coarse perlite or grit added to improve drainage.

As the first frond emerges, I turn the pot so that the frond points in the direction of the incidental light. After this time, the pot is NOT moved to prevent the developing frond from distorting. Even with older plants I do not move them whilst they are producing new leaves.

As for watering, I allow my plants to become quite dry before giving them a good watering. They will tolerate drought better than over watering!

Feeding takes place about every ten days with a liquid feed.

It may seem from all this that cycads are difficult, but if good seed is obtained, they are in fact very easy and rewarding plants to grow.

If possible, I would like to correspond with other cycad enthusiasts to discuss cultivation techniques and sources of seeds and I hope to see the observations of others printed in Chamaerops. Happy growing!

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