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San Diego Ambrosia
Ambrosia pumila
  
3 Nurseries Carry This Plant

About San Diego Ambrosia (Ambrosia pumila) 3 Nurseries Carry This Plant Ambrosia pumila is a rare species in the Asteraceae (Sunflower) family known by the common names San Diego Ambrosia and San Diego Ragweed. It is native to a very limited area in far southern California and Baja California where it grows in a variety of habitats along the coastal strip, inland valleys and foothills at elevations below 2,000 ft. Due to its rarity it is included on CNPS list 1B.1 and is listed as Endangered by the federal government. This is a perennial herb not exceeding half a meter in height. The leaves are gray-green, fuzzy, and divided into numerous minute lobes to give a feathery appearance. They are up to 13 centimeters long, not counting the winged petioles. The flower cluster is tipped with staminate (male) flower heads above several larger pistillate (female) heads. The pistillate heads each yield usually one fruit, which is a fuzzy burr only a few millimeters wide with short, soft spines. However, it rarely produces viable seed, usually spreading by its rhizome, forming clonal groupings. It is adapted to dry habitat, but only on upper floodplain fringes, or adjoining depressions containing vernal pools or similar structures. It is a plant of open habitat and is not tolerant of heavy shade. If not given supplemental summer water it will become deciduous but will come back from the rhizome after winter rain. This is not an easy plant to find and infrequently used in residential gardens. It is important for restoration projects in areas of appropriate habitat, and it may be useful in gardens seeking to specialize in rare plants of southern California.
Plant Description
Plant Type
Plant Type
Perennial herb

Size
Size
1.6 ft tall
3 ft wide

Form
Form
Spreading

Growth Rate
Growth Rate
Fast, Moderate

Dormancy
Dormancy
Summer Semi-Deciduous

Flower Color
Flower Color
Green, Yellow

Flowering Season
Flowering Season
Spring, Summer, Fall

Wildlife Supported
 
Species in the Ambrosia genus are host plant for the Bordered Patch butterfly

 
Butterflies & moths hosted ( 16 likely * ) SHOW ALL
*
Polygonia gracilis Image
Hoary Comma Polygonia gracilisPolygonia gracilis
*
Pholisora catullus Image
Common Sootywing Pholisora catullusPholisora catullus
*
Chlosyne lacinia Image
Bordered Patch Chlosyne laciniaChlosyne lacinia
*
Hyles lineata Image
White-lined Sphinx Hyles lineataHyles lineata
*
Orgyia vetusta Image
Western Tussock Moth Orgyia vetustaOrgyia vetusta
*
Mythimna unipuncta Image
Armyworm Moth Mythimna unipunctaMythimna unipuncta
*
Synchlora aerata Image
Wavy-Lined Emerald Synchlora aerataSynchlora aerata

Landscaping Information
Sun
Sun
Full Sun

Moisture
Moisture
Low, Moderate - High

Summer Irrigation
Summer Irrigation
Max 1x / month once established

Nurseries
Nurseries
Carried by 3

Cold Tolerance
Cold Tolerance
Tolerates cold to 15° F

Soil Drainage
Soil Drainage
Fast, Medium

Soil Description
Soil Description
Tolerates a variety of soils

Companion Plants
Companion Plants
In the wild it is associated with Saltgrass (Distichlis spicata), Mulefat (Baccharis salicifolia), Broom Baccharis (Baccharis sarathroides), California Buckwheat (Eriogonum fasciculatum), and Turkey-mullein (Croton setiger)

Propagation
Propagation?
Propagation is by rhizome cutting, rarely from seed

Natural Setting
Site Type
Site Type
Occurs primarily on upper terraces of rivers and drainages as well as in open grasslands, openings in coastal sage scrub, and occasionally in areas adjacent to vernal pools; may also be found in disturbed sites such as fire fuel breaks and edges of dirt roadways.

Climate
Climate
Annual Precipitation: 9.9" - 15.0", Summer Precipitation: 0.20" - 0.98", Coldest Month: 46.7" - 55.4", Hottest Month: 71.0" - 80.4", Humidity: 1.64" - 28.65", Elevation: 33" - 1960"

Alternative Names
Common Names: Dwarf Bur Ragweed, Dwarf Burr Ragweed, San Diego 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


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