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An Introduction to Cycad Reproduction
by Bane Cheek

Spring is the favorite time of year for gardeners the world over and cycad collectors are no exception. This is when these "slow" growing relics of a by-gone era begin to push new heads of foliage and cone. This is an exciting time because you can easily see the plants response to your year round care, plus, the added reward of cones and the chance to reproduce your specimens. Remember most cycads are highly endangered species and coning brings not only rewards but responsibility. Collectors bear a responsibility to propagate from the plants they own for the survival of the species. Collector propagation may be the only way many cycad species survive, since many species are either extinct in the wild or their populations so reduced reproduction is minimal. In the following paragraphs I will discuss Cycad Reproduction, with a practical emphasis. Much of the discussion will come from nearly 20 years of collecting and studying cycads and will not be specifically referenced; however, other more controversial points will be. The bibliography will include several references not cited within the text that cover these basics and are included for the readers benefit.

As with most organisms, cycads can reproduce via asexual or sexual reproduction. In asexual reproduction cycads produce stem offshoots or suckers (often called pups). These can be separated from the parent and rooted with a little care. I prefer to wait until fall, after the plants have had time to store lots of starch from a summer of active photosynthesis following that energy expensive time of growth. This is also when the dry season begins in most of Florida, reducing the risk of fungal growth. To remove offsets from the base of the plant, first remove most of the offsets foliage. Then gently pull back the soil and expose the offset. I do not like to remove small offsets; usually baseball size or larger is best. Gently rock the offset, you may even need to wash away excess dirt. What you're looking for is a point of attachment; surprisingly, a baseball sized offset may only be attached to the parent by a half inch of tissue. Slide a thin sharp blade between the two and cut the region as smoothly as possible; you may need to use a hammer to tap the blade. After removal, make sure the cut is clean on both the offset and parent. Parental care: Let the exposed cut dry a few days; this allows the wound to seal naturally; then apply a paste of fungicide, let dry, and cover with soil. Avoid keeping this plant wet for a few weeks. Offset care: If roots are present cover them with a moist towel and allow the wound to dry a few hours (if there are no roots, the wound may dry for 2 to 3 days); "paint" the bottom of the offset with a paste of fungicide and commercial rooting hormone. Plant in a well drained soil, and place in partial shade, keep warm and water sparingly. If the foliage begins to show signs of stress remove more or all of it. By spring, when the offset pushes new growth, it should be well rooted. Despite this, the new foliage may be shorter than the previous growth; this should change with the next flush of leaves. The advantages of asexual propagation are that you get a large plant faster which is also an exact copy of the parent, so if you know the sex of the parent, be sure to indicate that in your records or on your tag so you know the sex of the offset.

Sexual reproduction of cycads is a little more complicated. To begin with, cycads are dioecious, which means plants are either male or female. To date cycads can only be sexed after coning; no technique exists for early detection. The reproductive structure is specifically called a strobilus (often commonly called a cone); this is an aggregation of modified leaves which bear either pollen or ovules (which become seeds after fertilization and further development). The female strobilus in the genus Cycas is by far the most primitive and allows you to easily determine its leafy origin (Foster, 1974).

To distinguish between males and females, observe the cone as it is emerging. The male cone is more slender and possesses more and smaller sporophylls (cone scales). Under each are several pollen sacs, which can be seen as the cone matures. When the pollen is mature, the cone elongates and distinctive gaps can be seen between scales and the pollen begins to dehisce. If you tap the cone at this stage yellow pollen can be seen falling from the cone, at which time the cone is removed and placed on clean paper to collect the pollen. The female cone is more massive but will have fewer sporophylls, each of which will possess two to eight ovules. Shortly after the female cone has completely emerged, it will in some way open. In Zamias, such as our native coontie, this is easily seen. I've said more than once, "You can pollinate coontie with a bus," since the openings are so large and obvious. I would encourage new collectors, or those just starting to pollinate their own cycads, to keep a few common Zamias in pots so that they can experiment with pollination techniques on some easy species. Be sure when watching the females for signs of opening that you inspect the entire cone. Some cones only open at the top (some Encephalartos, ex. E. ferox) or bottom (all Dioon). Others never seem to open very wide. The only indication of opening may be the visibility of a lighter color between the cone scales; with a little pressure they will separate easily (Tang, 1986).

In a perfect world, the first day your female opens will be the day you're able to collect pollen from your male. However, timing is rarely exact, especially if you only have one male. If your male is slightly ahead of the female, simply place the pollen in the refrigerator. But if long term storage is needed the following procedure seems best:First, after collecting, dry the pollen for 24 hours over a desiccant like silica gel. Then place the pollen in a sealed container and freeze. This method will retain the viability of some of the pollen for three to five years (Osborne, 1991). There are several ways to pollinate the female. In Cycas, since the female does not form a cone you can simply shake and/or place the male cone over her when the sporophylls expand away from one another. In other species the pollen must be injected into the female. Wet and dry methods are most commonly used. Both can be used in conjunction with the removal of a cone scale or two near the tip of the cone, especially if it is difficult to inject pollen between the cone scales. In the wet method you mix the pollen in tap water and use a turkey baster or syringe to inject the solution between the cone scales. Start near the top and move around the cone. It is also beneficial to pollinate several days in a row, as long as the female remains open and your pollen holds out. Similarly, the pollen can be added dry, being gently blown in with a variety of devices. Each ovule in the cone will exude a sugary solution called the pollen drop. As this drop recedes, typically as the day progresses, this pulls the pollen into the ovule (Tang, 1993). Fertilization will usually take place several months later.

After pollination the female cone will close and expand tremendously. This is a good sign, but be aware that Encephalartos and Ceratozamias are both known for producing sterile seed. Needless to say all of the growth will put a heavy nutritional burden on the plant; a fully pollinated Lepidozamia peroffskyana cone can reach 90 lbs. Be sure to keep the plant well fertilized, especially with minor elements. Even the best growers will experience some nutrient deficiencies from time to time during heavy seed set. The female cone is often brightly colored and will remain on the plant for months. As the seed matures the cone begins to break down and its bright yellow, red or orange colored sarcotesta (seed coat) can be seen. I encourage you to leave the cone on the plant until it begins to break down to avoid premature harvest. The seed once collected should have the colorful sarcotesta removed; it contains germination inhibitors and may also harbor disease. Most cycad seed is not ready for immediate planting since the embryo must develop further. Many collectors will place the seed in a bag with moist spaghum, to keep it from drying out for a few months while the embryo matures. This is unnecessary in Dioon edule (and probably the other Dioons) which can be planted right away. A general estimation of seed viability can be made by float testing seeds in water; floaters are often bad, but this does not work universally so always plant these seeds as well. Remember some cycad seeds are dispersed by water and float naturally. A more precise method is to section the seed long-ways with a sharp knife and look for a developing embryo. The embryo may be rather small, 2 to 3mm in length, and may be attached to a string-like tissue, the suspensor. Coontie again is an easy species to try this with; you will notice as the embryo matures it will be nearly the entire length of the seed and begin to turn red toward the emerging (micropylar) end.

Before you plant the seeds soak them for 24 hours in tap water; the addition of fungicide and insecticide is also advisable. Sow the seeds in a deep container with well drained soil. They should be placed on the soil horizontally and not quite covered with soil. Keep warm and moist but not wet. Be patient; although some seeds will germinate within a few months, others from the same crop may take a couple of years.

In conclusion, propagating your cycads can be a personally rewarding experience. You are not only aiding an endangered species but seedling make good trading material to add new cycad species to your collection. You may even make new friends through seed or pollen exchange, so have fun with it.
 
 Illustrations: 1. Bowenia serrulata male cones; 2. Ceratozamia robusta male cone; 3. Cycas taiwaniana female cone; 4. Encephalartos chimanimaniensis female cone.

Bibliography
Foster, A.S., & Gifford, E.M.. 1974. Comparative Morphology of Vascular Plants. 2nd ed. W.H. Freeman & Co.
Jones, D.L.. 1993. Cycads of the World. Smithsonian Institution Press.
Norstog, K.J. & Fawcett, P.K.S.. 1989. Insect Pollination of Cycads. Encephalartos. 19:38-42.
Osborne, Roy., Robbertse, P.J., & Claassen, M.I.. 1991. The Longevity of Cycad Pollen. Encephalartos. 28:10-13.
Tang, W. 1986. Pollinating Cycads. Encephalartos. 8:16-19.
Tang, W. 1987. Cycad Seed & Seedlings. Encephalartos. 9:8-11.
Tang, W. 1989. Evolutionary Patterns in Cycad Cone Size & Shape. Encephalartos. 18:26-31.
Tang, W. 1989. Male Cycad Cone Structure & Function. Encephalartos. 20:25-28.
Tang, W. 1993. Nectar-Like Secretions in Female Cones of Cycads. The Cycad Newsletter. 2:10-13.

Note: This article was originally published on the author's website (http://www.gate.net/~cbreeze/cycads.html) and is reprinted here with permission.

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