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Ambrosia deltoidea

(Rabbit Bush)

Interesting Facts

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Common Names

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Common Names in English:

Rabbit Bush, Triangle Burr Ragweed, Triangle Bursage, Triangle Leaf Bursage

Description

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Family Compositae

The largest family of flowering plants , the Compositae (Asteraceae), comprising about 1,100 genera and more than 20,000 species and characterized by many small flowers arranged in a head looking like a single flower and subtended by an involucre of bracts. A head may consist of both ray flowers and disk flowers, as in the sunflower, of disk flowers only, as in the burdock, or of ray flowers only, as in the dandelion.

Tribe Heliantheae

The Heliantheae are a tribe of closely related genera of the sunflower family that can be readily recognized due to the association of a receptacular bract or chaff scale with each disk floret in the head . The heads usually include bisexual , actinomorphic disk florets with tubular corollas that have 4 or 5 distal lobes and also peripheral zygomorphic female or sometimes sterile florets with strap-shaped corollas that have 3 or fewer distal teeth. However, the ray flowers are sometimes absent and the heads are then discoid , containing only bisexual florets with tubular corollas. The pappus is absent or more commonly ranges from scales to stiff bristles . -- Gerald Carr.

Genus Ambrosia

Annuals , perennials , or shrubs , 10-400+ cm (usually rhizomatous ). Stems erect , decumbent , or prostrate , branched. Leaves usually cauline; opposite ± throughout or opposite (proximal ) and alternate or mostly alternate; sessile or petiolate ; blades (or lobes ) deltate, elliptic , filiform , lanceolate, linear , obovate , ovate , or rhombic (and most intermediate shapes ), usually pinnately, sometimes palmately lobed , ultimate margins entire or toothed , faces hairy or glabrate , usually gland-dotted or stipitate-glandular . Heads discoid (unisexual , pistillate proximal to or intermixed with staminates , staminates usually in racemiform to spiciform arrays; rarely, single plants all or mostly staminate or pistillate). Pistillate heads: phyllaries 12-30(-80+) in 1-8+ series, outer (1-) 5-8 distinct or ± connate , herbaceous, the rest (sometimes interpreted as paleae) ± connate, usually with free tips forming tubercles , spines, or wings (the whole becoming a hard perigynium or "bur") ; florets 1(-5+), corollas 0. Staminate heads: involucres cup-shaped to saucer-shaped , 1.5-6+ mm diam.; phyllaries 5-16+ in ± 1 series, ± connate; receptacles ± flat or convex ; paleae spatulate to linear, membranous, sometimes villous , hirtellous, and/or gland-dotted or stipitate-glandular, sometimes none; florets 5-60+; corollas whitish or purplish, ± funnelform , lobes 5, erect or incurved ; staminal filaments connate, anthers distinct or weakly coherent. Cypselae (black) ± ovoid or fusiform , enclosed within globose to obovoid , pyramidal , pyriform , obconic, or fusiform, hard, smooth , tuberculate , spiny , or winged "burs"; pappi 0. x = 18.

Species 40+: tropical to subtropical and temperate New World, mostly North America, some established in Old World.[1]

Physical Description

Species Ambrosia deltoidea

Shrubs , 30-80+ cm. Stems erect . Leaves mostly alternate; petioles 5-12+ mm; blades deltate to lance-deltate, 12-25(-35) × 5-12(-18) mm, bases cuneate to truncate , margins toothed , abaxial faces ± densely tomentulose (between veins), adaxial faces sparsely tomentulose, glabrescent . Pistillate heads clustered, proximal to staminates ; florets 2-3. Staminate heads: peduncles 0.5-3(-5) mm; involucres ± cup-shaped, 4-8 mm diam., tomentulose; florets 12-30+. Burs: bodies ± fusiform to globose , 3-4 mm, usually stipitate-glandular (little, if at all, tomentulose), spines 20-30+, scattered or on distal 1/2, ± subulate (the proximal basally flattened), 1-3 mm, tips usually straight, sometimes uncinate . 2n = 36. [source]

Some specimens are intermediate for the char­-acteristics that distinguish Ambrosia deltoidea and A. chenopodiifolia. The type of A. deltoidea may be better treated as conspecific with that of A. chenopodiifolia. [source]

Habit: Subshrub , Shrub

Flowers: Bloom Period: February, March, April, May. • Flower Color: inconspicuous, none

Size/Age/Growth

Size: 18-24" tall.

Habitat

Sandy washes, benches; 200-1000 m [2].

Biology

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Reproduction

Duration: Perennial

Growth

Culture: Space 18-24" apart.

Sunlight: Sun Exposure: Full Sun .

Moisture: Drought Tolerance: High

Temperature: Cold Hardiness: 9a, 9b, 10a, 10b. (map)

Taxonomy

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Synonyms

Franseria confertiflora< /i> (Dc.) Rydb. • Franseria deltoidea Torrey • Franseria strigulosa Rydb. • Gaertneria tenuifolia Harvey & Gray • Smithsonian Contr. Knowl. (2): 15. 1853

Notes

Name Status: Accepted Name .

Comment: Data Providers: CONABIO, Govaerts World Compositae Checklist A-G, IPNI, Tropicos. GCC LSID: urn :lsid:compositae.org:names:41ACE642-E0D0-4EA7-B592-16C502CA55D7

Last scrutiny: 14-Oct-09

Similar Species

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Members of the genus Ambrosia

ZipcodeZoo has pages for 36 species, subspecies, varieties, forms, and cultivars in this genus:

A. acanthicarpa (Annual Bursage) · A. ambrosioides (Ambrosia Bursage) · A. artemisifolia (Common Ragweed) · A. artemisiifolia (Annual Bur-Sage Ambrosia Artemisiifolia) · A. artemisiifolia L. var. artemisiifolia L. (Ragweed) · A. artemisiifolia L. var. paniculata (Michx.) Blank. (Annual Ragweed) · A. artemisiifolia var. artemisiifolia (Common Ragweed) · A. artemisiifolia var. elatior (Annual Ragweed) · A. artemisiifolia var. paniculata (Annual Ragweed) · A. bidentata (Lance-Leaf Ragweed) · A. canescens (Hairy Ragweed) · A. chamissonis (Beach-Bur) · A. cheiranthifolia (Rio Grande Ragweed) · A. chenopodiifolia (San Diego Ambrosia) · A. confertiflora (Ragweed) · A. cordifolia (Heartleaf Bursage) · A. deltoidea (Rabbit Bush) · A. dumosa (Burro Bush) · A. elatior var. elatior (Ragweed) · A. eriocentra (Hollyleaf Bursage) · A. grayi (Bur Ragweed) · A. helenae (Helen Ragweed) · A. hispida (Coastal Ragweed) · A. ilicifolia (Holly-Leaf Bursage) · A. intergradiens (Intergrading Ragweed) · A. linearis (Linear-Leaf Bursage) · A. peruviana (Peruvian Ragweed) · A. psilostachya (Cuman Ragweed) · A. pumila (Dwarf Burr Ragweed) · A. tenuifolia (Field Ragweed) · A. tomentosa (Bur Sage Ragweed) · A. trifida (Blood Ragweed) · A. trifida var. texana (Texan Great Ragweed) · A. trifida var. trifida (Great Ragweed) · A. × helenae (Helen Ragweed) · A. × intergradiens (Intergrading Ragweed)

More Info

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Further Reading

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Notes

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Contributors

Data Sources

Accessed through GBIF Data Portal February 16, 2008:

Identifiers

Footnotes

  1. John L. Strother "Ambrosia". in Flora of North America Vol. 21 Page 3, 9, 10, 25. Oxford University Press. Online at EFloras.org. [back]
  2. "Ambrosia deltoidea". in Flora of North America Vol. 21 Page 11, 14. Oxford University Press. Online at EFloras.org. [back]
Last Revised: 7/15/2012