Contains 15 accepted taxa overall.
Characteristics
Classification
Citation
AMARANTHUS Linnaeus, Sp. Pl. 989. 1753.
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TYPE: Amaranthus caudatus Linnaeus Lectotypified by Britton & A. Brown, Ill. Fl. N. U.S., ed. 2. 2: 1. 1913.
Species
| Scientific Name | Common Name | Herbarium Specimens | Status | Photos |
|---|---|---|---|---|
| Amaranthus albus | Tumbleweed Amaranth | |||
| Amaranthus blitoides | Matweed Amaranth, Prostrate Pigweed | |||
| Amaranthus cannabinus | Salt-marsh Water-hemp | |||
| Amaranthus crassipes var. crassipes | Spreading Amaranth | |||
| Amaranthus cruentus | Red Amaranth, Blood Amaranth, Purple Amaranth | |||
| Amaranthus hybridus ssp. hybridus | Smooth Amaranth, Green Amaranth, Hybrid Amaranth, Smooth Pigweed | |||
| Amaranthus palmeri | Careless-weed, Palmer’s Amaranth | |||
| Amaranthus polygonoides | Tropical Amaranth, Smartweed Amaranth | |||
| Amaranthus powellii | Green Amaranth, Powell's Amaranth | |||
| Amaranthus pumilus | Seabeach Amaranth, Dwarf Amaranth | |||
| Amaranthus retroflexus | ||||
| Amaranthus spinosus | Spiny Amaranth | |||
| Amaranthus thunbergii | Thunberg's Amaranth | |||
| Amaranthus tuberculatus | Inland Water-hemp | |||
| Amaranthus viridis | Slender Amaranth, Tropical Green Amaranth |
Identification Key
1. Stem nodes usually with paired spines
1. Stem nodes without spines
2
2. Plant dioecious
3
2. Plant monoecious, staminate and carpellate flowers intermingled or separated
6
3. Leaf blades linear-oblong, <1.1 cm wide, those subtending the inflorescence <0.5 cm wide
3. Leaf blades linear-oblong, lanceolate, to ovate, larger ones >1 cm wide, usually at least some subtending the inflorescence >0.5 cm wide
4
4. Plant (0.25)0.5-1.5(3) m tall; petioles commonly subequal to longer than the leaf blade; staminate flower bracts longer than 2 mm, mostly with prominent midribs; outer staminate tepals with prominent midribs, usually longer than the inner tepals; carpellate flowers with 5 tepals, at least some >2 mm long; utricle circumscissile dehiscent
4. Plant (0.25)1-3(9) m tall; petioles usually shorter than the leaf blade; staminate flower bracts 2 mm or shorter, midribs mostly not prominent or sometimes moderately prominent; outer staminate tepals without prominent midribs (sometimes moderately prominent), mostly not longer than the inner tepals; carpellate flower with 0-2 tepals, tepals usually <2 mm long; utricle indehiscent
5
5. Staminate bracts 1.5-2 mm long, midribs prominent; utricles 1-2.5 mm long; seeds 1-1.2 mm wide
5. Staminate bracts <1 mm long, midribs not prominent; utricles 2.5-4 mm long; seeds 2-3 mm wide
6. Inflorescences predominantly of axillary clusters or glomerules, distal nodes sometimes condensed into leafy spikes
7
6. Inflorescences predominantly terminal spikes and/or panicles, leafless or almost leafless at least in the distal part, axillary spikes or clusters usually also present
10
7. Pistillate flowers usually with 3 tepals
8
7. Pistillate flowers usually with (4-)5 tepals
9
8. Leaf blades obtuse or acuminate to short-mucronate or shallowly emarginate at apex; utricles dehiscent
8. Leaf blades usually deeply and broadly emarginate at apex; utricles indehiscent
9. Inflorescence axes thickened, becoming indurate at maturity
9. Inflorescence axes not thickened, not indurate at maturity
10. Inflorescence bracts shorter than tepals; tepals of pistillate flowers usually 2-3; utricles indehiscent
11
10. Inflorescence bracts usually exceeding tepals, sometimes shorter than tepals; tepals of pistillate flowers usually 5; utricles dehiscent
13
11. Utricles distinctly rugose, equaling or slightly exceeding tepals
11. Utricles smooth to faintly rugose, occasionally wrinkled or rugose in dry plants, distinctly exceeding tepals
12
12. Plants annual; leaf blades usually deeply emarginate at apex; utricles subglobose to obovate, compressed; seeds filling fruit almost completely
12. Plants short-lived perennial or annual; leaf blades retuse or shallowly emarginate at apex; utricles ellipsoid, slightly to distinctly inflated; seeds filling only proximal portions of fruit
13. Tepals of pistillate flowers acute, acuminate, to aristate at apex
14
13. Tepals of pistillate flowers obtuse, rounded, to emarginate at apex
15
14. Bracts shorter than 2 mm, shorter than tepals; style branches strongly spreading; seeds 0.8-1 mm wide
14. Bracts 2-7 mm, longer than or equaling tepals; style branches erect or slightly reflexed; seeds. 1-1.3 mm wide
15. Inflorescences drooping, usually bright red to purple, occasionally white or yellowish, rarely green; bracts subequal to tepals and usually not exceeding style branches at maturity; seeds white, ivory, reddish, brown, or black
15. Inflorescences erect or reflexed only at the tip, usually green, occasionally silvery green, sometimes reddish; bracts usually exceeding tepals and style branches; seeds brown to black
Genus Synonyms
| Synonym | Full Citation | Basionym | Type |
|---|---|---|---|
| No synonyms found. | |||