Amaranthus palmeri |
Amaranthus subg. Acnida |
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carelessweed, Palmer's amara nth, Palmer's pigweed |
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Habit | Plants glabrous or nearly so. | Plants dioecious. |
Stems | erect, branched, usually (0.3–)0.5–1.5(–3) m; proximal branches often ascending. |
erect to ascending, not fleshy. |
Leaves | long-petiolate; blade obovate or rhombic-obovate to elliptic proximally, sometimes lanceolate distally, 1.5–7 × 1–3.5 cm, base broadly to narrowly cuneate, margins entire, plane, apex subobtuse to acute, usually with terminal mucro. |
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Bracts | of pistillate flowers with long-excurrent midrib, 4–6 mm, longer than tepals, apex acuminate or mucronulate; of staminate flowers, 4 mm, equaling or longer than outer tepals, apex long-acuminate. |
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Inflorescences | terminal, linear spikes to panicles, usually drooping, occasionally erect, especially when young, with few axillary clusters, uninterrupted or interrupted in proximal part of plant. |
mostly terminal, well-developed spikes or spicate panicles. |
Staminate flowers | tepals 5, unequal, 2–4 mm, apex acute; inner tepals with prominent midrib excurrent as rigid spine, apex long-acuminate or mucronulate; stamens 5. |
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Pistillate flowers | tepals 1.7–3.8 mm, apex acuminate, mucronulate; style branches spreading; stigmas 2(–3). |
tepals absent or 1–5. |
Seeds | dark reddish brown to brown, 1–1.2 mm diam., shiny. |
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Utricles | tan to brown, occasionally reddish brown, obovoid to subglobose, 1.5–2 mm, shorter than tepals, at maturity walls thin, almost smooth or indistinctly rugose. |
indehiscent or dehiscence circumscissile. |
Amaranthus palmeri |
Amaranthus subg. Acnida |
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Phenology | Flowering summer–fall, occasionally spring–winter in southern part of its native range. | |
Habitat | Streambanks, disturbed habitats, especially agricultural fields, railroads, waste areas, roadsides | |
Elevation | 100-1000 m (300-3300 ft) | |
Distribution |
AR; AZ; CA; CO; FL; GA; IL; KS; KY; LA; MA; MD; MO; MS; NC; NE; NJ; NM; NV; NY; OH; OK; PA; SC; TN; TX; UT; VA; WI; WV; ON; Mexico [Introduced Europe, Asia, and Australia]
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North America; Mexico; Central America; n South America; introduced elsewhere |
Discussion | Originally native to the North American Southwest, from southern California to Texas and northern Mexico, Amaranthus palmeri at present is a successful invasive species, which is evident from its expansion both in eastern North America and overseas. Because of its rapid spread, the distribution data presented here are probably incomplete. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Species 9 (9 in the flora). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 4, p. 418. | FNA vol. 4, p. 415. |
Parent taxa | Amaranthaceae > Amaranthus > subg. Acnida > sect. Saueranthus | Amaranthaceae > Amaranthus |
Sibling taxa | ||
Subordinate taxa | ||
Synonyms | subg. Acnida | |
Name authority | S. Watson: Proc. Amer. Acad. Arts 12: 274. (1877) | (Linnaeus) Aellen ex K. R. Robertson: J. Arnold Arbor. 62: 283. (1981) |
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