Flora of North America species comparison

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Ambrosia chenopodiifolia

Ambrosia eriocentra

San Diego bur ragweed, San Diego bur-sage, San Diego burr ragweed

woolly bur-sage, woolly fruit bur ragweed, woollyfruit burr ragweed
Habit Shrubs, 30–80+ cm. Shrubs, 30–80(–120+) cm.
Stems

erect.

erect.
Leaves

mostly alternate;

petioles 5–20 mm;

blades ovate to rounded-deltate, 20–35(–50) × 18–30(–45) mm, bases broadly cuneate to ± truncate, margins toothed, abaxial faces ± densely tomentulose (between veins), adaxial faces sparsely tomentulose, glabrescent.

mostly alternate;

petioles 0–2 mm;

blades (± white abaxially) elliptic, lance-linear, or rhombic, 10–40(–60) × 5–15(–40) mm, bases ± cuneate, margins irregularly toothed to ± laciniate, abaxial faces densely strigillose, adaxial faces tomentulose and pilosulous.
Staminate heads

peduncles 0–3 mm;

involucres ± cup-shaped, 3–5 mm diam., tomentulose;

florets 12–20+.

peduncles 0–0.5 mm;

involucres saucer-shaped to shallowly cup-shaped, 4–8+ mm diam., tomentulose and/or pilose;

florets 12–25+.
Pistillate heads

clustered, proximal to staminates;

florets 2(–3).

clustered, proximal to staminates;

florets 1.
Burs

bodies obconic to fusiform, 4–6 mm, tomentulose (little, if at all, stipitate-glandular), spines 15–20+, scattered or on distal 1/2, ± subulate (the proximal basally flattened), 2–3 mm, tips usually uncinate, sometimes straight.

bodies obconic to fusiform, 3–5+ mm, densely villous and stipitate-glandular, spines 12–20+, scattered or mostly distal, ± subulate, 3–4 mm, tips straight.
2n

= 72.

= 36.

Ambrosia chenopodiifolia

Ambrosia eriocentra
Phenology Flowering Mar–Apr. Flowering Apr–May(–Jul).
Habitat Clays or sandy soils, among lava rocks Sandy and gravelly washes
Elevation 50–200 m (200–700 ft) 700–1700 m (2300–5600 ft)
Distribution
from FNA
CA; Mexico (Baja California, Baja California Sur)
[WildflowerSearch map]
[BONAP county map]
from FNA
AZ; CA; NV; UT
[WildflowerSearch map]
[BONAP county map]
Source FNA vol. 21, p. 14. FNA vol. 21, p. 13.
Parent taxa Asteraceae > tribe Heliantheae > subtribe Ambrosiinae > Ambrosia Asteraceae > tribe Heliantheae > subtribe Ambrosiinae > Ambrosia
Sibling taxa
A. acanthicarpa, A. ambrosioides, A. artemisiifolia, A. bidentata, A. chamissonis, A. cheiranthifolia, A. confertiflora, A. cordifolia, 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
A. acanthicarpa, A. ambrosioides, A. artemisiifolia, A. bidentata, A. chamissonis, A. cheiranthifolia, A. chenopodiifolia, A. confertiflora, A. cordifolia, A. deltoidea, A. dumosa, A. grayi, A. hispida, A. ilicifolia, A. linearis, A. monogyra, A. psilostachya, A. pumila, A. salsola, A. tomentosa, A. trifida
Synonyms Franseria chenopodiifolia Franseria eriocentra
Name authority (Bentham) W. W. Payne: J. Arnold Arbor. 45: 419. (1964) (A. Gray) W. W. Payne: J. Arnold Arbor. 45: 423. (1964)
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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