Ambrosia cheiranthifolia A. Gray:
Mexico (Mesoamerica)
United States (North America)

Note: This information is based on publications available through Tropicos and may not represent the entire distribution. Tropicos does not categorize distributions as native or non-native.

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: Coastal south Texas (Cameron, Kleberg, Jim Wells, Nueces Cos.) south to Tamaulipas, Mexico.

Historic Range:
U.S.A. (TX)

Perennials or subshrubs, 10–30+ cm (rhizomatous and/or soboli­ferous, colonial). Stems erect. Leaves opposite (distal sometimes alternate); petioles 0; blades lanceolate or lance-elliptic to lance-oblong or oblanceolate, 20–50(–70+) × 8–12(–25+) mm, rarely ± pinnately lobed (lobes ± deltate), bases cuneate (then rounded), margins entire or toothed, abaxial faces densely strigose (silvery gray), adaxial faces strigillose. Pistillate heads clustered (in axils), proximal to staminates; florets 1(–2). Staminate heads: peduncles 1–4+ mm; involucres cup-shaped (sometimes with black nerve in each lobe), 3–4+ mm diam., strigillose; florets 8–18+. Burs: bodies ± pyriform to ± globose, 2–3+ mm, glabrous or strigose, spines (1–)3–5+, scattered, stoutly conic, 0.4–0.8+ mm, tips straight (often each with black nerve). 2n = 72.

Ambrosia cheiranthifolia may be characterized by median leaves of flowering stems entire and silky-pubescent (Correll and Johnston, 1970).

Comments: Grasslands and various mesquite-dominated shrublands on soils ranging from heavy clays to lighter-textured sandy loams. Most commonly found in coastal prairie communities over the Quaternary-age Beaumont Formation.

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: 6 - 20

Comments: About 15-20 occurrences: 5 in S. Texas (Cameron, Kleberg, Jim Wells, Nueces Cos.) and 1 in Tamaulipas, Mexico.

United States

Rounded National Status Rank: N2 - Imperiled

Rounded Global Status Rank: G2 - Imperiled

Reasons: Only an estimated 20 population centers survive, and since most popluations are clonal, these may represent very few genetically different individual plants. The species' geographic range is limited to coastal south Texas and northeastern Mexico. Much of its original habitat has been converted to agricultural fields and pastures. The remnant, fragmented native prairies and savannahs are threatened by continued habitat distruction, agricultural chemicals, and by invasive, non-native grasses, which are commonly planted in the area.

Current Listing Status Summary

Status: Endangered
Date Listed: 08/24/1994
Lead Region:   Southwest Region (Region 2) 
Where Listed:


Population detail:

Listing status: E

For most current information and documents related to the conservation status and management of Ambrosia cheiranthifolia, see its USFWS Species Profile

Comments: Threatened by continued habitat distruction, agricultural chemicals, and by invasive, non-native grasses, which are commonly planted in the area.

Biological Research Needs: Population biology; habitat requirements.

Needs: 5; 1 in each county in Texas and 1 in Tamaulipas, Mexico; probably 100 acres needed to preserve habitat.

Comments: Distinct species in large genus.