South Texas Ambrosia
Ambrosia cheiranthifolia

Introduction: South Texas Ambrosia blooms in the fall, but its flowers are not showy and may be missed by the casual observer. It spreads through rhizome (underground stems) growth and a single individual may be represented by several to 100 stems. This species may occur in association with slender rush-pea (Hoffmannseggia tenella), which is also federally- listed as endangered. While the species does not appear to survive intensive plowing, moderate disturbance may enhance growth and spread of the species. Studies are currently addressing the effect of mowing on the species.

Date First Listed-- Endangered, 1994

Reason for Concern: Loss of habitat has led to the decline of this species. Conversion of habitat to agricultural fields and urban areas has limited the amount of habitat available for colonization. In addition, introduced species such as buffelgrass (Cenchrus ciliaris) and King Ranch bluestem (Bothriochloa ischaemum var. songaricus) compete with this and other natives of the coastal prairie. Invasion of prairie by shrub and tree species also contributes to loss of available habitat, although the species does occur among scattered woody plants. Disturbance associated with activities occurring along road right-of-ways where the species is found may also be detrimental. The species was previously reported from Jim Wells and Cameron Counties in addition to currently verified localities in Nueces and Kleberg Counties.

Size:  Rhizomatous perennial plant, 6 inches to 1 foot tall with simple leaves about 3 inches long and 1.5 inches wide.

Habitat:  Grows at low elevations in open clay-loam to sandy-loam prairies and savannas.

Range:  Nueces and Kleberg Counties (historically in Cameron and Jim Wells Counties) in the Gulf Prairie region of Texas; also known from the state of Tamaulipas in Mexico.

Reproduction: Flowers are inconspicuous with male and female flowers separate on the same plant. Asexual reproduction from rhizomes is common.

Population: It occurs at six general locations in Nueces and Kleberg Counties in Texas.

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