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Vascular Plants of California
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Key to Amaranthus

View taxon page for Amaranthus

(For a list of species in Amaranthus, use the above link.)

Jepson Manual glossary definitions can be seen by moving your cursor over words underlined with dots.

1. Dioecious

2. Plant in hand pistillate

3. Perianth parts 1–2, 1 narrowly , 1 rudimentary or 0 ..... A. tuberculatus var. rudis (2)

3' Perianth parts 5, well developed, fan- or spoon-shaped

4. Bracts <= perianth parts ..... A. arenicola (2)

4' Bracts > than perianth parts

5. Plant ± glabrous; outer perianth parts ±  ..... A. palmeri (2)

5' Plant glandular-hairy especially on bracts; outer perianth parts  to ± notched, mucronate ..... A. watsonii (2)

2' Plant in hand staminate

6' Bracts (1.4)2–6 mm

7. Outer perianth parts , spine-tipped; bracts >= perianth parts ..... A. palmeri (2)

7' Outer perianth parts mucronatebracts <= perianth parts

8. Inflorescence axis and bracts glabrous ..... A. arenicola (2)

8' Inflorescence axis and bracts generally sparsely glandular-hairy ..... A. watsonii (2)

1' Monoecious

9. Nodes with 2 spines ..... [A. spinosus]

9' Nodes without spines

10. Perianth parts 1–3, only 1 well developed ..... A. californicus

10' Perianth parts (2)3–5, all well developed.

11. Pistillate perianth parts fan-shaped, margins  or finely  ..... A. fimbriatus

11' Pistillate perianth parts not fan-shaped, margins 

12. Inflorescence of  clusters only, or axillary and terminal

13. Perianth parts (3)4–5

14. Perianth parts narrow-ovate to seeds 1.3–1.7 mm ..... A. blitoides

14' Perianth parts narrow-spoon-shaped; seeds 0.9–1.1 mm ..... A. torreyi

13' Perianth parts (2)3

15. Fruit bracts 1.5–4 mm, tip ± spined ..... A. albus

15' Fruit bracts <= 1 mm, tip not spined

16. Stem hairy distallyfruit 2–3 mm, smooth ..... A. deflexus

16' Stem ± glabrousfruit 1.2–1.5 mm, wrinkled

17. Leaf tip  or ± notched; seeds dull, dotted ..... [A. viridis]

17' Leaf tip deeply notched to 2-lobed; seeds shiny, only margins dotted ..... [A. blitum subsp. emarginatus]

12' Inflorescence terminal only

18. Inflorescence green; bractsstigmaseeds brown to black; often weedy

19. Perianth parts spoon-shaped to obovate, overlapping,  in age, tip rounded to ± notched ..... A. retroflexus

19' Perianth parts  to lance-oblong, not overlapping, , tip  to awned

20. Leaf blades rhombic-ovate or widely inflorescence of many thin, flexible branches; bracts 2–4 mm ..... A. hybridus

20' Leaf blades , rhombic to widely inflorescence of few rigid,  branches; bracts 4.5–6(8) mm ..... A. powellii

18' Inflorescence brightly colored, not green; bracts generally <= stigmaseeds white to ± red-brown or black; cultivated, rarely escaped

21. Inflorescence main axis generally drooping or nodding; perianth parts widely spoon-shaped, margins overlapping, tip  to rounded ..... [A. caudatus]

21' Inflorescence not drooping or nodding; perianth parts  to  (obovate), margins not overlapping,  to  (rounded)

22. Inflorescence  to flexible, lateral axes thin, flexible, 3–8(12) cm, 0.5–1 cm wide; bracts 1.8–2.5 mm; fruit tip abruptly narrowed to a beak ..... [A. cruentus]

22' Inflorescence lateral axes thick, stiff, 9–20(30) cm, 1.2–2 cm wide; bracts 3–5(6) mm; fruit tip gradually narrowed ..... [A. hypochondriacus]

 

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Citation for the whole project: Jepson Flora Project (eds.) . Jepson eFlora, http://ucjeps.berkeley.edu/eflora/ [accessed on ]

Citation for an individual treatment: [Author of taxon treatment] [year]. [Taxon name] in Jepson Flora Project (eds.) Jepson eFlora, [URL for treatment]. Accessed on .

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