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Giant Ragweed

Ambrosia trifida

Photo by joanbstanley
Published on Project Noah
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33.0849, -97.0694

Field Notes

Description:

Description: This is a native annual plant from 3-12' tall, branching occasionally. The green stems are covered with white hairs. The opposite leaves are up to 12" long and 8" across. The larger leaves are divided into 3 or 5 lobes, usually serrated along the margins, and have long petioles that are sometimes winged. The smaller leaves near the base of an inflorescence are lanceolate and often hairy underneath. Many of the upper stems terminate in a cylindrical spike of flowers, about 3-6" long, with one or more smaller spikes near its base. The small flowers are are yellowish green and devoid of petals and sepals. They occur in small drooping clusters less than ¼" across on short pedicels, and are densely arranged all around each spike. The fine pollen of the male flowers is easily carried aloft by the wind. This typically occurs during late summer or early fall. The seeds are large, tough-coated, and remain viable in the soil for several years. The root system is fibrous.

Habitat:

This plant was growing in dappled shade on a stream bank in the greenbelt.

Notes:

Best known as the cause of late summer hay fever misery, ragweed also boasts of less well-known medicinal uses.
Ragweed’s medicinal properties include: astringent, antiseptic, emetic, emollient, and febrifuge. Early American physicians recognized ragweed’s medicinal uses, and Native Americans valued it as a topical and internal remedy. Healers and herbalists prepare remedies from the roots and leaves. Crush the leaves and apply the juice to soothe insect bites and poison ivy rashes. Native Americans prepared a poultice from crushed leaves to relieve swelling and prevent infection.

Ragweed also provides aid for internal ailments. Herbalists value ragweed root tea as a remedy for nausea, fevers, and menstrual disorders; Native Americans used the root tea as a laxative. For years, Ozark herbalists have treated diarrhea with tea prepared from the leaves. Ragweed pollen is used in homeopathic remedies for treatment of hay fever symptoms.

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