For those of you who are fortunate enough to have coning sized cycads, this is the time of year that your cones should be evident. Occasionally mature coning sized cycads will put out one cone or multiple cones each year. However cones don’t necessarily come every year. Female plants are more prone to skip a year or two between coning cycles to allow the plant to regenerate its food reserves. The female plants use much more of their food reserves than do the male plants for cone production, mostly due to their larger cone size and structure.
For nearly all cycads that are in cultivation and are not in or near their natural habitat, natural pollination does not occur. This is primarily because the native insect species that typically facilitate the pollination process are usually habitat specific and not available to do their part in the pollination process of cultivated plants, which are located outside of their natural habitat.
Hand pollination has proven to be a useful means of producing viable seed for many years. Time does not permit detailed explanation of all of the known techniques of human-assisted pollination. Generally speaking, when male and female plants produce their cones, and when the male cone begins to shed pollen, the human assistant can collect the pollen from the male cone by cutting the cone from the cycad and laying it on a piece of butcher paper (or something similar) for several days in a cool dry area. The male cone will, in time, shed much of the fine pollen grains onto the paper. Lightly tapping the cone over the paper will aid in maximizing your pollen collecting. I have found the garage to be an acceptable location for this process.
Ideally your male and female coning plants will be in sync. The female cone will give subtle signs that it is receptive to pollination. The timing of the introduction of pollen is critical to your success at producing viable seed. The female cones of different genus of cycads can have different indicators that signal receptivity. Most of the closed cone genus female cones, Encephalartos, Dioon, and Macrozamia to name a few, are receptive when the cone scales begin to separate and create openings that allow the insect pollinators to enter to the inside of the cone. The window of time of female receptivity can last as little as a couple of days to as long as a week or two. More studies are needed to assign more definitive time frames of receptivity for each species.
The introduction of pollen is primarily performed in one of two methods. These methods work best on all genus, except the genus Cycas, whose female cone structure is different, and would require an alternate method of pollen application. The “dry method” is to collect the pollen from the paper on which the male cone has been resting. Then pour or puff the pollen with a straw into the central axis of the female cone just below the top cluster of smaller cone scales. Many growers will completely remove one to three of these upper level cone scales to facilitate the dispersion of pollen into the hollow labyrinth of spaces within the female cone.
The “wet method” is achieved by mixing the dry pollen with water in a plastic bottle with a cap and adding a couple of drops of liquid soap (Green Soap), which works as a wetting agent to help the pollen-laden water to coat all interior surfaces of the female cone. Then pour from the plastic bottle ample quantities of pollen solution down through the chambers of the female cone. A squeeze bottle with a pointed spout, a turkey baster, or a large plastic basting syringe can also be used to deliver the pollen solution.
For either method, if possible, repeat the pollination process every few days to increase your odds, as long as you have pollen and as long as the female cone appears to be receptive.
If your male and female cones are NOT in sync, and if the male plant cones first, the pollen can be collected and placed in small air tight containers with a little desiccant, and stored for several months in the freezer. Clearly label the containers with species and date collected.
If your efforts have been successful, you will be rewarded with viable seed, when the post harvest ripening period has been completed and the seed has fully developed. In most cases this takes place within six months to a year. This is another area that could benefit from further study to determine the post harvest ripening periods for the seed of each species. Producing seed is one of the many joys of growing cycads.
Collection and propagation of seed will be discussed in a future blog.
Grow and prosper,