Ambrosia artemisiifolia (Common ragweed)

Ambrosia artemisiifolia L.

Common ragweed, ragweed, bitterweed, annual ragweed, roman-wormwood, blackweed, carrot weed, hay fever weed, stammerwort, stickweed, tassel weed, American wormwood

Kingdom	Plantae	Plants, but not fungi, lichens, or algae
Subkingdom	Tracheobionta	Vascular plants—plants with a “circulatory system” for delivering water and nutrients
Division	Magnoliophyta	Flowering plants, also known as angiosperms
Class	Magnoliopsida	Dicotyledons—plants with two initial seed leaves
Subclass	Asteridae	A large class that encompasses asters
Order	Asterales	Flowering plants with a central disk flower and surrounding petals, like daisies
Family	Asteraceae	The aster family, which also includes daisies and sunflowers; from the Greek ἀστήρ, “star,” for the star-shaped flowers
Genus	Ambrosia	It is not known why this genus is named from the Greek ἀμβροσία, or “food of the gods”
Species	artemisiifolia	Means “mugwort leaves”

About plant names...

Nobody seems to know why ragweed, best known for bedeviling allergy sufferers worldwide, is a member of genus Ambrosia, the Greek food of the gods said to be responsible for the gods’ immortality. Perhaps, as this Wikipedia article suggests, the name simply refers to ragweeds’ own apparent immortality: they are robust competitors considered by many to be invasive, and are among the few plants that show up on more noxious weed lists than on naturalist web sites. Ragweed is a North American native plant.

Identification: Plants are 8-79" (20-200 cm) tall, with stems that are green, pink-purple, or purple-spotted, with long, rough hairs. They are fairly easy to miss—even when in flower, they tend to blend in with their surroundings. Leaves are deeply divided, a bit similar to carrot leaves, 1½-4" (4-10 cm) long, pinnate or bipinnate. Flowerheads are long (1-4" (2.5-10 cm)) and narrow, covered with tiny yellow flowers ¹/₁₆-⅛" (2-4 mm) in size. At first the flowers are green.

Medical: Goldenrods, the widespread, showy, yellow-topped weeds, are often blamed for causing allergies because they disperse pollen at the same time that ragweed does. But ragweed is the culprit. As for medicinal benefits for ragweed, I wasn’t able to find any.

Online References:

Ambrosia artemisiifolia on the Virginia Tech Weed Identification Guide

Ambrosia artemisiifolia at Illinois Wildflowers

Ambrosia artemisiifolia on Wildflowers of the United States

Ambrosia artemisiifolia on the USDA Plants Database

Ambrosia artemisiifolia on www.iucngisd.org

8/11/2010 · Nashua River Rail Trail, Groton Center, Groton, Massachusetts
≈ 12 × 15" (29 × 38 cm)

Ambrosia artemisiifolia description by Thomas H. Kent, last updated 25 May 2020.

8/4/2010 · Nashua River Rail Trail, Groton Center, Groton, Massachusetts
≈ 8 × 12" (20 × 31 cm) ID is uncertain

8/18/2010 · J. Harry Rich Woods, off Nod Rd., Groton, Massachusetts
≈ 2½ × 3" (6.6 × 8.4 cm)

8/18/2010 · J. Harry Rich Woods, off Nod Rd., Groton, Massachusetts
≈ 4 × 3" (10 × 8.3 cm)

Range:

About this map...