Acanthospermum australe |
Acanthospermum |
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Paraguay starburr, Paraguayan starbur, Paraguayan starburr, southern starbur |
starbur, starburr |
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Habit | Plants 10–60(–120+) cm. | Annuals (sometimes persisting), 10–60(–120) cm. | ||||||||
Stems | ± procumbent. |
erect to ± prostrate (repeatedly “forked”). |
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Leaves | blades deltate to ± rhombic or ovate, 13–37 × 7–32 mm, faces sparsely scabrellous to glabrate or glabrescent, gland-dotted. |
cauline; opposite; petiolate or ± sessile; blades mostly elliptic to deltate, rhombic, or ovate, sometimes lyrate, ultimate margins entire or toothed, faces usually pilosulous to sericeous or scabrellous, sometimes glabrate or glabrescent, usually gland-dotted. |
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Involucres | ± hemispheric, 3–5 mm diam. (becoming ± rotate in fruit). |
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Receptacles | convex, paleate (paleae cuneate to spatulate, ± conduplicate or flattish, membranous). |
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Ray florets | 5–8, pistillate, fertile; corollas yellowish (tubes shorter than to equaling laminae, laminae ovate to elliptic or linear). |
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Disc florets | 3–8(–12+), functionally staminate; corollas yellowish, tubes shorter than funnelform or campanulate throats, lobes 5, deltate. |
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Phyllaries | persistent (outer) or falling, 10–13 in 2 series (outer 4–6 herbaceous, inner 5–8 each investing a ray ovary, enlarging in fruit to form a perigynium, shed with enclosed cypsela). |
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Fruits | plumply ellipsoid to fusiform, weakly compressed, 7–9+ mm, 5–7-ribbed, lacking terminal spines, prickles ± uncinate, mostly along ribs. |
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Heads | radiate, 1(–3) in “forks” of branches (terminal, appearing axillary by sympodial growth). |
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Cypselae | each enclosed within and shed with an often hardened, ± prickly perigynium (the ultimate “fruits” plumply ellipsoid to fusiform, or ± compressed); pappi 0 or rudimentary. |
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x | = 11. |
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2n | = 22. |
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Acanthospermum australe |
Acanthospermum |
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Phenology | Flowering year round, mostly Jul–Aug. | |||||||||
Habitat | Disturbed, often sandy sites | |||||||||
Elevation | 0–300 m (0–1000 ft) | |||||||||
Distribution |
AL; AR; DC; FL; GA; LA; MA; MS; NC; OR; PA; SC; TX; VA; South America [Introduced in North America; also introduced in Mexico, West Indies, Central America, Europe, Asia, Africa, Pacific Islands (Hawaii)]
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mostly tropical to warm-temperate New World [Introduced in North America; also introduced in Old World] |
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Discussion | Reports of Acanthospermum xanthioides (Kunth) de Candolle from New York are evidently based on specimens of A. australe. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Species 6 (3 in the flora). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 21, p. 37. | FNA vol. 21, p. 36. | ||||||||
Parent taxa | Asteraceae > tribe Heliantheae > subtribe Melampodiinae > Acanthospermum | Asteraceae > tribe Heliantheae > subtribe Melampodiinae | ||||||||
Sibling taxa | ||||||||||
Subordinate taxa | ||||||||||
Synonyms | Melampodium australe | |||||||||
Name authority | (Loefling) Kuntze: Revis. Gen. Pl. 1: 303. (1891) | Schrank: Pl. Rar. Hort. Monac. 2: plate 53. (1820) | ||||||||
Web links |