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Wisconsin Natural Resources magazine

Wisconsin Natural Resources magazine

A saprophytic plant, Indian pipe draws its nutrients from fungi on the forest floor. The fungi capture nutrients the small plant can use.© Scott Nielsen

August 2002

Pipe dreams

Look for the ghost flowers of August.

Anita Carpenter

A saprophytic plant, Indian pipe draws its nutrients from fungi on the forest floor. The fungi capture nutrients the small plant can use.

© Scott Nielsen

August blossoms with a rainbow of colors. Sun yellow goldenrods and deep purple asters wave in hot summer winds. Lavender milkweeds provide sweet nectar for hungry monarch butterflies. Spikes of blood red cardinal flowers decorate wetlands while blue bottle gentians hide among towering prairie grasses.

In the shadowy understory of an oak-pine woods, a plant with no color rises from the brown, needle-strewn earth. Small clusters of white translucent Indian pipe, Monotropa uniflora, give a ghostly image to the scene. Other common names for this unusual plant are corpse plant, ice plant or ghost flower.

Although Indian pipe looks like a parasite, it belongs to the same plant family (Ericaceae) as blueberry, leatherleaf, trailing arbutus and wintergreen. Unlike the others, Indian pipe lacks chlorophyll, the green pigment necessary for the plant to photosynthesize.

Photosynthesis, as all attentive science students learn, is a biochemical process in which green plants use energy from sunlight to convert water and carbon dioxide into carbohydrates and energy for their own use.

If Indian pipe is not a parasite and lacks the ability to photosynthesize, how does it obtain its nourishment?

The plant has a microscopic helper, but we must look underground to discover it. Indian pipe is a saprophyte, a plant without green color that derives its food from organic materials in the soil. Its root system is a ball of densely matted root fibers that are surrounded by a fungus. This fungus breaks down organic matter and the nutrients are absorbed by the Indian pipe's fine roots.

This symbiotic relationship between a beneficial fungus and the roots of a seed-producing higher plant is termed a mycorrhiza. These same mycorrhizae relationships help beech trees, some pine trees and some orchids survive.

If Indian pipe obtains its nutrients from below ground, why does it expend the energy to send up a stem? The answer is to flower and reproduce. Atop each three- to nine-inch scale-covered stem is a solitary, odorless flower as waxy white and translucent as the stem. The Latin species name "uniflora" refers to one flower. Because it also lacks color, the flower appears to be an extension of the stem. Take a look inside and you'll see that the nodding head reveals all the parts of a typical flower: stamens, stigma, style and ovary.

Only the young flowers of Indian pipe nod. In this position, you can imagine how earlier observers gave the plant its common name. After fertilization, thought to be by insects, the flower turns upward. The genus name Monotropa means "one turn," referring to the way the flower lifts to an upright position. Numerous seeds mature inside a capsule as the stalk toughens and turns black. Eventually the capsule splits and releases really tiny seeds that resemble a fine brown powder that drift on the wind.

There's a lot left to learn about Indian pipe's life history. As you explore a woods during summer, perhaps you'll discover which insects pollinate this perennial plant and how they do it. Maybe you'll learn what time of day or night pollination occurs and when the seeds germinate.

Don't pick this plant, for the stem rapidly deteriorates into a gooey black blob. Just enjoy Indian pipe in its native habitat and congratulate yourself for taking the time to investigate such an interesting plant.

Anita Carpenter explores the vacant lots, the leaves and the litter in the fields and woodlands near her Oshkosh home.