Friday, April 15, 2016

Skunk Cabbage

Very Rare New Brunswick Plant

One of our first spring blooms is a unique, very rare (S2) plant, Skunk Cabbage, Symplocarpus foetidus.

Skunk Cabbage (N Poirier Photo)
A member of the Araceae family, Skunk Cabbage grows in the wet, soft soil of swamps and alder thickets.  It is found only in a few sites in the southern part of New Brunswick.  Its range includes northern US and southern Canada.  The Araceae family also includes Jack-in-the-Pulpit and the Calla Lily.  

Skunk Cabbage
Skunk Cabbage blooms even before the snow has melted.  What we see is a purplish-brownish and sometimes greenish triangular shoot sticking out of the snow or clump of dead grass.  Sometimes we don't even see them before we unfortunately step on them.  As you can see in the first photo above, the plant is often sticking literally out of the snow.  That is because skunk cabbage is one of the rare thermogenic plants.  It creates its own heat, so the snow melts around it.  Apparently the heat is created by the female plants only and they do it through the cellular respiration system.  The mitochondria in the cells create enough heat to melt the snow.  This heat also vaporizes the oils that create the strong smell of the plant, thus attracting pollinating insects.  The literature tells us that the heat generated by the plant can raise the air temperature around the plant by 15º to 35ºC.  The bad smell produced by the plant also attracts carrion-feeding insects.

Skunk Cabbage
The anatomy of the plant is unusual.  The purplish cup in which the flower develops is called the spathe; the roundish flower-head, the spadix.  We noted that the spadices (plural of spadix) were of two types, indicating distinctive male and female flowers.  In the photo above, notice the spadix inside the purplish spathe.  The greenish spathe shown there is more developed.  In the photos below, note the male and female flowers indicated by the different spadices.

Male Spadix

Female Spadix
The skunk cabbage has another interesting physiological characteristic, contractile roots!  After the roots grow, they contract, pulling the plant deeper into the soil.  This makes the root deeper and deeper making it very difficult to dig up.  We dug into the soil around a plant and found a very large root with a complicated system appearing to run in many directions.  See the photo below showing the size of the root.  The skunk cabbage grows its leaves after fertilization of the flowers.  The leaves are very large, up to a metre tall.  They are a bluish green colour and are heart-shaped.

Skunk Cabbage Showing Large Root

False Skunk cabbage is often mistaken for true Skunk Cabbage.  This plant is a medium yellow-green in colour and is really False Hellebore, Veratrum virile.

Skunk cabbage is a toxic plant (and so is False Skunk Cabbage).  The plant produces needlelike crystals of calcium oxalate which, if taken into the mouth, become embedded in the mucous membranes and cause intense irritation and a burning sensation.  This can be a particular problem for livestock if pasturage is poor and skunk cabbage is present.

Mrs. William Starr Dana wrote some interesting historical notes about Skunk Cabbage in her book, 'How to Know the Wild Flowers' written in 1893.   She said (and we can certainly agree) that it is unfortunate that our earliest spring flower was endowed with such an unpleasant odour that it earned the name, 'skunk cabbage'.  She tells us that the plant was once given the name, 'bear-weed',  by early Swedish settlers in Pennsylvania.  They thought the bears relished this plant in the spring (notwithstanding that it is toxic)  and that it "must have been a hot morsel, as the juice is acrid, and is said to possess some narcotic power, while that of the root, when chewed, causes the eyesight to grow dim".

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