March 11, 2010

Skunk Cabbage

by Susan Post

Skunk cabbage, found in the northern 2/3's of the state in open swamps, marshes, and wet woodlands, is Illinois earliest flowering plant. Before the woods awake in spring it begins to bloom in late February or early March. Sheltered and hidden by a few decaying leaves, it bravely pokes through the moist earth to face howling winds, freezing temperatures, and sometimes even snow.

The first part of the plant to appear is not the leaves, but a fleshy protective hood, called a spathe. The hood, emerging dark and ruddy from the mud, is brownish-purple with yellow and green streaks and spots. Although the hood may be 3 to 6 inches tall, its color blends with the surrounding decaying leaves on the forest floor. Using energy stored for months in starchy, tuberous roots, the plant generates enough heat not only to melt through leftover snow, but to maintain summer-like temperatures inside the hood on subfreezing mornings. This is important as each hood incubates a knob-like structure, called a spadix, which is covered with tiny, cold-sensitive blossoms. The insulating walls and curved design of the hood allow eddies of warmed air to circulate around the developing flowers.

All parts of the plant, when bruised or crushed, give off an offensive odor that has been described as a cross between garlic, onions, and decaying flesh. The heat produced by the plant as it grows helps to volatilize the odor, which in turn, attracts carrion flies that are necessary for cross pollination.

A few days after the hood emerges, the leaves pierce the mud. Still unsure of the weather, they remain rolled into compact cones and cower behind the protective hood. As spring advances the odor subsides, the flowers shrivel, and the leaves begin to grow and spread. By summer the skunk cabbage is no longer the ground hugging spathe, but knee-high clumps of caladium-like leaves.

March 8, 2010

Winter Stoneflies

By Susan Post

The life of fall and winter stoneflies is an exception to the rule that insect activity ceases with the approach of cold weather. Twenty species of the state's 65 native stoneflies emerge during November through March. With a habit of congregating in places exposed to the warming sun's rays, you can see them crawling about on exposed tree trunks, fence posts, or on rocks located close to a stream. The white concrete bridges characteristic of Illinois' highways are a beacon of warmth to a stonefly.

Stoneflies belong to the insect order Plecoptera. In appearance stoneflies are about a half an inch in size, have two pair of wings, and are rather drab in color. The adults, although terrestrial, are seldom found away from water. They are poor fliers with crawling the preferred mode of transportation. The eggs and nymphs are aquatic. The nymphs are often found under stones in streams, hence the common name —stonefly. The nymphs of the winter stoneflies are chiefly plant feeders. The adults feed on blue-green algae or not at all. The nymphs emerge from the water, find a suitable perch and metamorphose into an adult. The adults mate, lay eggs and die, usually living less than a month. The whole life cycle is complete in a year.

Although sunbathing in Illinois from November through March generally lacks appeal to most humans, the bridges over creeks emptying into the Middle Fork of the Vermillion River, or the clear, rocky streams of Southern Illinois are perfect places to absorb the fleeting sunlight of winter and to see Illinois winter stoneflies.

January 24, 2010

White concrete bridges

Beacons of warmth

Nude sunbathers gather

Looking for love

Absorbing weak sunlight

Coupled in pleasure

Winter stoneflies above Stoney Creek

On 8 March, 2010, winter stoneflies were observed on the bridge over the Middle Fork of the Vermilion River at Kickapoo State Park.

What Are Natural Divisions?

Scientists have divided the terrestrial part of the earth into large ecological regions called biomes. Examples of worldwide biomes include tropical rainforest, Asian steppe, African savanna, and a host of others. The North American continent also has biomes, such as the Arctic tundra, Sonoran desert, and Appalachian forest.

Illinois, too, has a diversity of landscapes that can be described by differences in topography, glacial history, bedrock, soils, and the distribution of native plants and animals. Using these natural features, Illinois can be divided into 14 natural divisions. The natural divisions of Illinois were defined in 1973 in a technical report authored by then state botanist John Schwegman and colleagues. According to Schwegman, “Natural divisions are geographic regions of a larger entity like a state or a continent. A division contains similar landscapes, climates, and substrate features like bedrock and soils that support similar vegetation and wildlife over the division’s area. Natural divisions help conservationists classify land for purposes like protecting natural diversity.”

These 14 divisions were further partitioned into 33 subdivisions. Over the years, Illinois’ natural divisions have proven very useful to the natural area preservation movement within the state. They have helped biologists categorize and prioritize Illinois’ 90+ natural habitats for preservation efforts. Illinois was one of the first states to have its natural divisions defined and this classification system has guided the development of the state’s nature preserve system, the Illinois Natural Areas Inventory, and the Illinois Natural Areas Plan.

We will showcase each of these 14 Natural Divisions in the coming weeks, as well as the newly determined 15th Natural Division for Illinois.