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Western Ragweed
Ambrosia psilostachya
  
About Western Ragweed (Ambrosia psilostachya) 7 Nurseries Carry This Plant 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
Plant Type
Perennial herb

Size
Size
3.5 - 7 ft tall
1 ft wide

Form
Form
Spreading

Dormancy
Dormancy
Winter Semi-Deciduous

Flower Color
Flower Color
Green

Flowering Season
Flowering Season
Summer, Fall

Wildlife Supported
 
Birds, butterflies, grasshoppers.

 
Butterflies & moths hosted ( 2 confirmed , 20 likely * ) SHOW ALL

Landscaping Information
Sun
Sun
Full Sun

Moisture
Moisture
Low, Moderate - High,

Summer Irrigation
Summer Irrigation
Max 1x / month once established

Nurseries
Nurseries

Cold Tolerance
Cold Tolerance
Tolerates cold to 15° F

Soil Drainage
Soil Drainage
Fast, Medium, Slow

Soil Description
Soil Description
Adaptable. Soil PH: 5.2 - 8.2

Common uses
Common uses
Groundcovers

Companion Plants
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
Site Type
Commonly occurs throughout California on roadsides, disturbed areas, and dry fields.

Climate
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


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


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