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Conyza canadensis

Conyza canadensis (L.) Cronquist

 

Horseweed, Canada Horseweed, Canadian Horseweed

KingdomPlantaePlants, but not fungi, lichens, or algae (from Stearn’s Botanical Latin)
SubkingdomTracheobiontaVascular plants—plants with a “circulatory system” for delivering water and nutrients
DivisionMagnoliophytaFlowering plants, also known as angiosperms
ClassMagnoliopsidaDicotyledons—plants with two initial seed leaves
SubclassAsteridaeA large class that encompasses asters
OrderAsteralesFlowering plants with a central disk flower and surrounding petals, like daisies
FamilyAsteraceaeThe aster family, which also includes daisies and sunflowers; from the Greek ἀστήρ, “star,” for the star-shaped flowers
GenusConyzaFrom Greek konops, “flea,” for the use of the leaves in beds as a flea repellant
Speciescanadensis“From Canada”

About plant names...

Horseweed is a native weed that is widespread in North America, now also found in Europe, Asia, Africa, and South America. It is a serious problem in some regions, com­peting actively with crops.

Identification: Plants are 20-79" (50-200 cm) in height, with a single erect stem that has bristly hairs on it. Leaves grow alternately from the stem in a pattern that looks whorled, but isn’t. They are all about the same length and orientation, making the plant resemble a green cylinder. Leaves are narrowly lanceolate or oblanceolate, 3-4" (7.6-10 cm) × ½" (1.3 cm). They are mostly untoothed, but have a few teeth toward their tips, and they have small white hairs along their edges. The top of the plant branches into a shape like the top of an ice cream cone, which becomes covered with a profusion of little flowers. The flowers are greenish-white, but only ⅛" (3.2 mm) in size. They are composite flowers, producing tiny white ray flowers as well as itsy-bitsy yellow disk flowers, but their small size and coloring overall is barely noticeable. Flowers appear from June to October. Although horseweed is big and common, you are likely to overlook it completely unless it starts muscling out your vegetables—it just isn’t a showy plant.

Edibility: Young leaves and seedlings are edible when cooked. Dried leaves have a flavor said to be similar to that of tarragon. An oil extracted from the leaves is used as a flavoring agent.

Medical: Plants produce dermatitis in some people. The common name sneezeweed derives from its use as a snuff to induce sneezing in herbal medicine, in hopes of lessening cold symptoms. Its smoke has been used as an insect repellant. Like many common plants, it has a host of other purported medical uses, among them treatment of gastrointestinal problems, rheumatism, dysentery, internal haemorrhages, gonorrhoea, and menstrual problems.

Online References:

Conyza canadensis at Illinois Wildflowers

Conyza canadensis on www.eattheweeds.com

Conyza canadensis on Plants for a Future, a resource and information centre for edible and otherwise useful plants

Conyza canadensis on CalPhotos

Conyza canadensis at Minnesota Wildflowers

Conyza canadensis on luirig.altervista.org

Conyza canadensis on biology.burke.washington.edu

Conyza canadensis on eFloras

Conyza canadensis (Horseweed, Canada Horseweed, Canadian Horseweed)

8/2/2012 · Nashua River Rail Trail, near Nashoba Hospital, Ayer, MA
≈ 6 × 9" (14 × 22 cm)

Conyza canadensis (Horseweed, Canada Horseweed, Canadian Horseweed)

8/20/2012 · Nashua River Rail Trail, Groton Center, Groton, MA
≈ 3½ × 5" (9.2 × 13 cm)

Conyza canadensis (Horseweed, Canada Horseweed, Canadian Horseweed)

8/2/2012 · Nashua River Rail Trail, near Nashoba Hospital, Ayer, MA
≈ 5 × 8" (13 × 19 cm)

Conyza canadensis (Horseweed, Canada Horseweed, Canadian Horseweed)

8/20/2012 · Nashua River Rail Trail, Groton Center, Groton, MA
≈ 6 × 9" (15 × 23 cm)

Conyza canadensis (Horseweed, Canada Horseweed, Canadian Horseweed)

8/20/2012 · Nashua River Rail Trail, Groton Center, Groton, MA
≈ 4½ × 7" (11 × 17 cm)

Conyza canadensis (Horseweed, Canada Horseweed, Canadian Horseweed)

8/18/2009 · Nashua River Rail Trail, Groton, MA
≈ 10 × 17" (26 × 42 cm) ID is uncertain

Conyza canadensis (Horseweed, Canada Horseweed, Canadian Horseweed)

8/17/2013 · Hopkinton State Park, Hopkinton, MA
≈ 6 × 8" (15 × 20 cm)

Conyza canadensis (Horseweed, Canada Horseweed, Canadian Horseweed)

7/20/2013 · Wooden Bridge, East Pepperell, MA
≈ 7 × 11" (18 × 28 cm)

Conyza canadensis description by Thomas H. Kent, last updated 30 Oct 2013.

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Conyza canadensis (Horseweed, Canada Horseweed, Canadian Horseweed)

7/31/2012 · Bemis Rd Conservation Area, Pepperell, MA
≈ 7 × 8" (18 × 20 cm) ID is uncertain

Conyza canadensis (Horseweed, Canada Horseweed, Canadian Horseweed)

7/31/2012 · Bemis Rd Conservation Area, Pepperell, MA
≈ 14 × 19" (34 × 48 cm) ID is uncertain

Conyza canadensis (Horseweed, Canada Horseweed, Canadian Horseweed)

8/20/2012 · Nashua River Rail Trail, Groton Center, Groton, MA
≈ 7 × 11" (18 × 27 cm)

Conyza canadensis (Horseweed, Canada Horseweed, Canadian Horseweed)

7/20/2013 · Wooden Bridge, East Pepperell, MA
≈ 4 × 4" (10 × 10 cm)

Conyza canadensis (Horseweed, Canada Horseweed, Canadian Horseweed)

7/20/2013 · Wooden Bridge, East Pepperell, MA
≈ 8 × 12" (21 × 31 cm)

Conyza canadensis (Horseweed, Canada Horseweed, Canadian Horseweed)

7/31/2012 · Bemis Rd Conservation Area, Pepperell, MA
≈ 14 × 21" (34 × 52 cm) ID is uncertain

Conyza canadensis (Horseweed, Canada Horseweed, Canadian Horseweed)

8/16/2013 · Nashua River Rail Trail, Groton Center, Groton, MA
≈ 7 × 10" (16 × 25 cm)

Conyza canadensis (Horseweed, Canada Horseweed, Canadian Horseweed)

8/16/2013 · Nashua River Rail Trail, Groton Center, Groton, MA
≈ 7 × 7" (17 × 16 cm)

Conyza canadensis (Horseweed, Canada Horseweed, Canadian Horseweed)

8/16/2013 · Nashua River Rail Trail, Groton Center, Groton, MA
≈ 7 × 7" (16 × 18 cm)

Conyza canadensis (Horseweed, Canada Horseweed, Canadian Horseweed)

8/22/2013 · Beaver Brook Assn Conservation Lands, Hollis, NH
≈ 7 × 10" (16 × 25 cm)

Range:

About this map...