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heartleaf bursage, Tucson bur ragweed, Tucson burr ragweed

Habit Shrubs, 30–50+ cm.
Stems

erect.

Leaves

mostly alternate;

petioles 3–35 mm;

blades deltate to rounded-deltate, 10–35(–80) × 10–30(–70) mm, bases cordate to truncate, margins coarsely toothed, abaxial faces densely puberulent (including veins), adaxial faces strigillose to scabrellous and gland-dotted.

Staminate heads

peduncles 0–1 mm;

involucres cup-shaped, 2–3(–5) mm diam., strigillose;

florets 8–30+.

Pistillate heads

clustered, proximal to staminates;

florets (1–)2.

Burs

bodies ± globose to fusiform, 3–4+ mm, tomentulose and stipitate-glandular, spines 8–20+, scattered, ± subulate (basally navicular), 1–2 mm, tips straight or uncinate.

Ambrosia cordifolia

Phenology Flowering Mar–Apr.
Habitat Sandy washes, benches
Elevation 700–1200 m (2300–3900 ft)
Distribution
from FNA
AZ; Mexico (Sinaloa, Sonora)
[WildflowerSearch map]
[BONAP county map]
Source FNA vol. 21, p. 14.
Parent taxa Asteraceae > tribe Heliantheae > subtribe Ambrosiinae > Ambrosia
Sibling taxa
A. acanthicarpa, A. ambrosioides, A. artemisiifolia, A. bidentata, A. chamissonis, A. cheiranthifolia, A. chenopodiifolia, A. confertiflora, A. deltoidea, A. dumosa, A. eriocentra, A. grayi, A. hispida, A. ilicifolia, A. linearis, A. monogyra, A. psilostachya, A. pumila, A. salsola, A. tomentosa, A. trifida
Synonyms Franseria cordifolia
Name authority (A. Gray) W. W. Payne: J. Arnold Arbor. 45: 421. (1964)
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