||The Secret Flowers of Bon Echo
Alison Lake Park Naturalist
One of the simple pleasures of visiting Bon Echo in spring is seeing the wide variety of flowers scattered on the forest floor. But some flowers are not so simple to see. In fact, some plants produce two types of flowers: the flowers that we see and the second, invisible, flowers. These are the secret flowers of Bon Echo.
While flowers are beautiful to us, to a plant flowers are solely for the challenge of reproduction. A simple strategy for plant reproduction is something that is easily seen: flowers produce pollen that is carried to another flower so that cross-pollination can occur and seeds can be produced for the next year. Just how that pollen gets to another flower can be a fascinating process in itself but most often it is simply a process of wind blowing pollen from one flower to another of the same species. Anyone who has been in Bon Echo in mid-June has seen this method in action with the enormous clouds of yellow pollen floating down from the surrounding White Pines (Pinus strobus)
onto the surface of Mazinaw Lake. Some of that pollen will reach other White Pine flowers but most of it blows onto the lake, the road, all the other plants growing nearby, a passing deer and even onto you. It is a matter of sheer chance that some pollen will actually end up blowing into the right species of flower at the right time and achieve cross-pollination. To compensate, these trees produce enormous amounts of pollen to increase the odds of success.
Other plants have a less haphazard strategy. Instead of relying on arbitrary gusts of wind to spread pollen, some flowers will actually bribe insects and birds into doing the job for them. By producing nectar as a high calorie reward for hummingbirds, bees, butterflies and other flying insects, flowers ensure that pollen is carried on the wings, legs and mouth-parts of these creatures as a direct delivery to the next flower. This is a highly efficient and successful strategy for these plants.
However, even this method is not fool-proof so some plants will resort to a guaranteed back up plan. This ‘Plan B’ results in the secret flowers of Bon Echo.
|Take the common violet (Viola Spp.) for instance. This small woodland plant grows on the forest floor among other plants, competing for sunlight, warmth and moisture. It is unlikely that even if a breeze did make it down to the forest floor any pollen caught up in it would travel very far. The tiny blooms are showy and offer up a pleasant scent to attract insects to do the work of pollination but the violet produces another flower that absolutely guarantees the production of a seed without any help at all.
If you wanted to see this flower you would have to dig, because this is an underground flower! As strange as it seems the violet is producing the flower we have come to know and appreciate up top, while down below it has produced a flower without showy petals or sweet nectar because this is a flower that will never open. It is known as a cleistogamous
or ‘closed’ flower (literally a ‘closed marriage’ from the Greek, kleistos
`closed‘ and gamous
`marriage’). Because it is closed, pollen will never get out to another flower to pollinate it. So what gives? The secret to this flower’s success is that this is a flower that is meant to pollinate itself and produce a seed right there underground without opening or ever being seen.
Seems like a very clever way to produce a seed with little effort doesn’t it? As is often the case this could be too good to be true because this method of seed production creates a disadvantage and a new challenge for the violet. The disadvantage is that this underground seed is a perfect clone of the parent plant, with none of the advantages of a new combination of superior genes of a neighbouring flower. The challenge is that new seed is going to grow right next to the parent plant so that if an unfortunate circumstance befalls the parent plant it will likely also befall the clone resulting in the death of both plants and the end of that genetic line.
But wait, this little violet has one more trick up its sleeve to deal with this last problem.
Each underground violet seed has a juicy energy-rich sac attached to it that just happens to be very attractive to ants. Ants will seek out these underground seeds and take them sometimes many metres away to a colony where the energy-rich treat is eaten without harming the seed. Ants, being the neat and fastidious creatures they are, take the seed out of the colony as garbage and throw it in the ant `dump’. The ant garbage dump is an excellent place for a seed to germinate and a new plant to grow. Finally our long-suffering violet has achieved its goal of a new plant germinating and growing to produce flowers of its own.
Jason J. Dombroskie
||In addition to violets, the exquisite Fringed Polygala (Polygala paucifolia) can also be found in Bon Echo showing off its uniquely purple flowers above ground in May and hiding its colourless, closed underground `secret’ flowers in June. Just another case of ‘Plan B’ in action.
When it comes to spring flowers in Bon Echo, sometimes there really is more than meets the eye