Western Ragweed, Ambrosia psilostachya

About Western Ragweed (Ambrosia psilostachya) 9 Nurseries Carry This Plant

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Ambrosia psilostachya is a species of ragweed known by the common names Cuman ragweed, perennial ragweed, and western ragweed. It is native to most of North America including all of southern Canada, nearly all of the continental United States, and the northern half of Mexico. It is a common plant in many habitat types, including disturbed areas such as roadsides. It can be found in parts of Eurasia as an introduced species. This is an erect perennial herb growing a slender, branching, straw-colored stem to a maximum height near two meters, but more often remaining under one meter tall. Leaves are up to 12 centimeters long and vary in shape from lance-shaped to nearly oval, and they are divided into many narrow, pointed lobes. The stem and leaves are hairy. The top of the stem is occupied by an flower cluster which is usually a spike. The species is monoecious, and the flower cluster is composed of staminate (male) flower heads with the pistillate heads located below and in the axils of leaves. The pistillate heads yield fruits which are achenes located within oval-shaped greenish-brown burs about half a centimeter long. The burs are hairy and sometimes spiny. The plant reproduces by seed and by sprouting up from a creeping rhizome-like root system. This plant had a number of medicinal uses among several different Native American groups.

Plant Description

Plant Type

Perennial herb

Size

3.5 - 7 ft tall
1 ft wide

Form

Spreading

Dormancy

Winter Semi-Deciduous

Flower Color

Green

Flowering Season

Summer, Fall

Wildlife Supported

Birds, butterflies, grasshoppers.
Butterfly host plants

Butterflies & moths hosted ( 2 confirmed

, 20 likely * ) SHOW ALL

Gnorimoschema saphirinellaGnorimoschema saphirinella

Cosmopterix opulentaCosmopterix opulenta

Hoary Comma Polygonia gracilisPolygonia gracilis

Common Sootywing Pholisora catullusPholisora catullus

Bordered Patch Chlosyne laciniaChlosyne lacinia

Western Tussock Moth Orgyia vetustaOrgyia vetusta

Armyworm Moth Mythimna unipunctaMythimna unipuncta

Landscaping Information

Sun

Full Sun

Moisture

Low, Moderate - High,

Summer Irrigation

Max 1x / month once established

Nurseries

Carried by 9

Cold Tolerance

Tolerates cold to 15° F

Soil Drainage

Fast, Medium, Slow

Soil Description

Adaptable. Soil PH: 5.2 - 8.2

Common uses

Groundcovers

Companion Plants

Ambrosia psilostachya can do well in a variety of conditions, so the soil type of your garden will best inform which other plants to choose. Consider using other natives that do well in sunny, sandy sites, such as Nuttall's Scrub Oak (Quercus dumosa), Desertbells (Phacelia campanularia), or the Bristly Matilija Poppy (Romneya trichocalyx).

Natural Setting

Site Type

Commonly occurs throughout California on roadsides, disturbed areas, and dry fields.

Climate

Annual Precipitation: 3.0" - 93.0", Summer Precipitation: 0.15" - 3.49", Coldest Month: 31.3" - 57.4", Hottest Month: 56.9" - 89.3", Humidity: 0.46" - 39.89", Elevation: -190" - 6525"

Alternative Names

Common Names: Cuman Ragweed, Perennial Ragweed

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Sources include: Wikipedia. All text shown in the "About" section of these pages is available under the Creative Commons Attribution-ShareAlike License. Plant observation data provided by the participants of the California Consortia of Herbaria, Sunset information provided by Jepson Flora Project. Propogation from seed information provided by the Santa Barbara Botanical Garden from "Seed Propagation of Native California Plants" by Dara E. Emery. Sources of plant photos include CalPhotos, Wikimedia Commons, and independent plant photographers who have agreed to share their images with Calscape. Other general sources of information include Calflora, CNPS Manual of Vegetation Online, Jepson Flora Project, Las Pilitas, Theodore Payne, Tree of Life, The Xerces Society, and information provided by CNPS volunteer editors, with special thanks to Don Rideout. Climate data used in creation of plant range maps is from PRISM Climate Group, Oregon State University, using 30 year (1981-2010) annual "normals" at an 800 meter spatial resolution.

Links: Jepson eFlora Taxon Page CalPhotos Wikipedia Calflora

Western Ragweed

Ambrosia psilostachya

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Western RagweedAmbrosia psilostachya

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Western Ragweed

Ambrosia psilostachya