By: Sorcha Masterson
Date: May 12, 2005
At this time of year we are all longing for signs of spring. If you’ve recently wandered in any of the marshes, bogs swamps or moist areas of the Sea to Sky corridor, you’ve probably seen one of the first signs of spring protruding through the last remnants of winter snow; the bright yellow of the skunk cabbage (Lysichiton americanum).
Skunk cabbage is the first flower to bloom in spring and it has been seen as early as late January during mild winters in our area. The first part of the skunk cabbage to appear is the “spathe,” which is essentially a group of bright yellow leaves 10-15 cm in height that enclose the flowers. The leaves of the spathe form what is described as a hood that envelopes the flowers, leaving a small opening on one side. The flower head, which is a round to spherical shaped club 2 cm in diameter, is called a “spadix.” The spadix consists of many tightly packed small flowers. But these flowers are not what we think of when we visualize flowers, as they have no petals. Instead they have only four pale yellow “sepals,” which are the bud leaves that usually enclose the petals. These rolled sepals enclose both the “stamen,” which is the male plant organ responsible for producing the pollen and the “style,” the female organ that is pollinated and produces the seeds.
In late spring the skunk cabbage sends up tightly rolled leaves that slowly unfurl and grow up to 1.5 metres in length and 60 cm in width. These leaves are the largest of any North American native plant. By mid June, the flower head swells and develops into the fruit. The fruit looks like a small, egg shaped ear of corn about 5 cm in diameter. They are green to reddish and ripen to black as the summer progresses.
If you have seen a skunk cabbage in the last few weeks, you may have noticed that despite there still being some snow in the area, there is little or none around the plant itself. This is because in the two or so weeks when the spadix bears pollen, the temperature within the plant’s spathe is 20-40ºC warmer than the surrounding air. The skunk cabbage produces this heat as oxygen is used to convert starch from the roots of the plant into sugar. This sugar is then used as energy for the plant’s biological processes, ie. growth.
If you move in for a closer look you will learn how the skunk cabbage obtained its name. The leaves when bent or bruised produce a not overly offensive, musky, skunky smell. If you happen to put your nose closer to the spathe you will notice the smell is somewhat stronger here.
So why would a plant waste valuable energy producing heat and smell? Well, sex of course, or rather its consequence – reproduction. In the early spring, the only insects that seem to be around are flies. Flies at this time of the year are looking for carrion, such as dead mice or birds in which to lay their eggs. Thus the skunk cabbage creates the musky, skunk-like, carrion-like odour, to attract the flies. The flies will crawl into the spathe, lay their eggs. This should simultaneously ensure pollination. To assist the flies in locating the carrion odour, the skunk cabbage uses heat. As we know, hot air rises, so the hot, carrion-scented air produced in the spathe seeps out the small opening and rises, creating a vortex which draws more air into the spathe, perpetuating the cycle. Some researchers think that the flies may also crawl into the spathe on cool spring nights to find shelter and warmth.
So, on your next walk when you spot the bright yellow of a skunk cabbage, take a moment and move in for a closer smell, feel the noticeable warmth around the spathe and marvel at the complexity of this spring-time flower.