Guilleminea densa, Small Matweed
Scientific Name: Guilleminea densa
Common Name: Small Matweed
Also Called: Matweed
Family: Amaranthaceae, Pigweed Family
Synonyms: (Illecebrum densum, Brayulinea densa)
Size: Up to 2 inches, 12 or more inches wide.
Growth Form: Forb/herb woolly, prostrate, mat forming along the ground, stems numerous from strong taproots.
Leaves: Shiny green; opposite, basal rosettes, petiolate, paired leaves of unequal size, oblong or ovate, tips of leaves pointed, glabrous on upper leaf surface and matted white hairs on lower surfaces.
Flower Color: White; flowers with sepals only, flowers in irregular clusters in leaf axils, bracts present, seeds red or brown.
Flowering Season: May to October
Elevation: 2,500 to 6,000 feet.
Habitat Preferences: Various habitats in mid- to high-elevations, open areas, grasslands, pinyon-juniper and oak-woodland areas and disturbed areas.
Recorded Range: Primarily in the southwestern United States in CA, AZ, CO, NM, TX, OK, MD and SC. Introduced in MD and SC. Also found in northern and central Mexico. It is found in the central, southern and northeastern portions of Arizona. Introduced and naturalized in parts of Africa and Australia.
North America & US County Distribution Map for Guilleminea densa.
U.S. Weed Information: No data available.
Invasive/Noxious Weed Information: No data available.
Wetland Indicator: No data available.
Threatened/Endangered Information: No data available.
Genus Information: 1 species in Guilleminea in the United States found in range described above. 2 varieties in Guilleminea densa, both native to Arizona;
Guilleminea densa var. aggregate, Small Matweed and
Guilleminea densa var. densa, also Small Matweed.
Comments: Small Matweed is a member of the Pigweed or Amaranth family and superficially resembles Khakiweed, Alternanthera caracasana also an Amaranth found in Arizona. Both are distinctive looking low-growing shiny green plants.
The genus was named in honor of French botanist Jean Baptiste Antoine Guillemin (1796 - 1842).