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===Introduction:===
For quite a long time it was believed that cycads were
pollinated through the action of wind. While this may be true
in certain cases more recent research indicates that specific
insects are more likely to be the vectors responsible for
pollination in cycads. Much research still needs to be done
in this field especially in connection with Australian cycads.
At this stage I can offer some personal observations
confirming the very limited role of air-borne dispersal of
cycad pollen.

Just recently a customer at my nursery told me he had
observed some ripe seeds in a cone of a
''[[Zamia furfuracea]]''
plant in his garden. I asked whether he had done any hand
pollination and he replied that he had not. I decided to have
a look and was able to confirm his observation. The plants
concerned were growing in a very exposed position near the
summit of a hill overlooking much of the surrounding
countryside. A male plant with some dried-up cones was
growing about two metres away slightly downhill so that
prevailing seabreezes would blow pollen towards the female
plant which now had some ripe fully formed seeds in its cone.
What particularly interested me was the fact that the seeds
were all in a ring around the top of the cone. There were
only 6 seeds in a cone which could easily have produced more
than a hundred seeds indicating that the rate of pollination
was very poor indeed. The location of the seeds around the
cone near the top corresponded to the way the cone opens when
receptive to pollen. It was apparent that pollination was
only effectire where the pollen was able to enter direcfiy
through the opening in the cone but the pollen was definitely
not distributed through the remainder of the cone. This
points to the fact that, where insect pollinators are absent,
wind pollination is only accidental and relatively
ineffective.

The problem with insect pollinators is that they appear to
be very specific so that a certain species of insect is
associated very closely with one or more species of cycads.
In the absence of the correct pollinator it appears that
other insects will not do the job. I have observed bees in
great numbers frequenting the male cones of
''[[Cycas revoluta]]''.

European bees visited the cones but were unable to enter as
they were too large but the much smaller native bees were
observed carrying away quantities of pollen. The problem was
that they were only flcetingly interested in the females
"cones". Once they realized there was no pollen in them they
confined their interest to the male cones and of course were
of no help at all in the pollination process. Of more
interest in the case of ''Cycas revoluta''
was a small unidentified beetle found in reasonable numbers
in both male and female cones. What their interest in the
cones is and what benefit they obtain from being there is not
known. It was observed that they were mating in the cones but
whether they were actually reproducing in the cones is also
not known. Although the fact that these insects were found in
both male and female cones might suggest that they could be a
factor in pollination, this is by no means certain as it
would depend on the insects moving back and forth between
male and female plants. At present it has not been possible
to find anyone who could identify these insects so it is not
known whether they are native or introduced. The only cycads
native to this area are ''[[Macrozamia miquelii]]'' and
''[[Macrozamia lucida]]'' but I have not observed the same insects in
cones of ''M. lucida'' in my nursery. At present I need
all the ''Cycas revoluta''
seeds I can get so I have hand pollinated cones to maximize
seed production. As a result I do not know whether they might
be effective in pollinating in the absence of hand
pollination. I would be interested in the observations of any
readers who have cycads in their gardens particularly as to
the presence of insects and whether pollination of cones has
taken place without human assistance.

Another observation I have made is with ''M. lucida''. A
friend had a number of mature plants on his dairy farm. He
did not want these plants and was slashing the leaves
regularly and told me I was welcome to remove them. I
re-established these plants in my garden and soon they
produced both male and female cones. I noted that quite a
considerable number of small weevils were present in the
cones and presumably playing a role in pollinating. What was
interesting was that year after year the number of weevils
decreased until they are now completely absent. It would seem
to me that unless there is a reasonably large number of
plants in a locality the insect population cannot be
maintained.

There are a number of implications for people interested in
cycads. From the growers' point of view it is apparent that
very little pollination will take place unless this is done
artificially. This is done quite easily by collecting pollen
from the male cones and, using a camera lens brush with a
blower bulb on the end, picking up the pollen and blowing it
into the receptive female cones. Most cones open when
receptive and pollen can be blown through the openings. I
have found this quite effective in most cases so that often
there is dose to 100% pollination. From the point of view of
conservation there are very great implications. In cases
where plants are lost from the natural environment it is
often possible to take cultivated plants and replace them
into the habitat they once occupied. With cycads this may not
be feasible. The insect pollinators appear to be very
specific in their association with cycads, often living in a
symbiotic relationship with them. When the population of
cycads of a given species in a locality falls to very low
levels the insect may become extinct. When cultivated cycads
are reintroduced into the area to replenish the population
they may do well and it may appear that the procedure has
been very successful. The problem is that without the insect
pollinators there will be no natural regeneration and in the
long run it will all be a waste of time unless there is human
intervention on a continual basis. Another consequence is
that in cases where the population of cycads in an area
becomes too low and the insect pollinator cannot survive
there is not much point in trying to protect the remainder of
the plants and thereby hope that the population will recover.
Without the pollinator this will never happen.

All the above probably may not apply to at least some
species in the genus '''''Cycas''''' It is well known that
''[[Cycas rumphii]]'', ''[[Cycas circinalis]]'' and
''[[Cycas thouarsii]]'' have seeds which contain spongy tissue so
that they readily float in water. It is thought that by this
means they have spread from island to island throughout the
range that they presently occupy. It would be most unlikely
that the insect pollinator would accompany the seeds yet
these cycads are reproducing freely over a vast range, on
islands separated by great expanses of water. It appears that
not a great deal is known as to how these cycads are
pollinated and what insects (which would presumably have been
present on remote locations before the cycads seeds arrived)
may be responsible.

Perhaps it is possible that a pollinator insect may be found
somewhere that will pollinate cycads indiscriminately. If
this was possible it would be a significant help in saving
natural cycad populations from total extinction. It is
certain that the subject of cycad pollinators is a vital one
for those who wish to conserve these fascinating plants. It
is to be hoped that more research can be done on this subject.
</div>
</div>

===Contributed by: ===
Will Kraa (from '''Palms & Cycads''' No 40, Oct - Dec 1993).<br/>

===External Links:===
<p>[https://www.google.com/search?q=Cycad+Pollination&num=10&sa=Google+Search Google],
[https://images.google.com/images?q=Cycad+Pollination&hl=en&btnG=Google+Search GoogleImages],
<p>
[[Category:Cycad|Pollination]]
[[Category:Palm|Cycad_Pollination]]

Cycad Pollination - Revision history

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P>Pacsoa at 21:40, 23 September 2024