Amaranthus L. Amaranthus Amaranthus, L.

2. Amaranthus L. View in CoL View at ENA 2

Annual, rarely perennial herbs; monoecious or dioecious. Leaves usually alternate. Bracteoles 3-5, small and herbaceous or membranous and spinescent. Perianth-segments 0-5, linear or lanceolate to spathulate. Styles and stigmas 2-3. Fruit dry, membranous, indéhiscent or dehiscing transversely. Seeds vertically compressed.

In the following descriptions characters of the perianth refer to female flowers.

All the species are ruderals or weeds. Most of them have been introduced into Europe and are usually casual in the north and centre. This account includes only those species that occur frequently or are known to be naturalized.

A. caudatus L. , Sp. Pl. 990 (1753), perhaps native in S. America, with long pendent red or rarely green inflorescences is commonly cultivated for ornament and sometimes occurs as a casual. Literature: A. Thellung in Ascherson & Graebner, Syn. Mitteleur. FI. 5 (1): 225-356 (1914). A. W. Kloos in Robyns, FI. Gén. Belg. (Spermat.) 1; 306-35 (1953). S. Priszter, Ann. Sect. Horti- Viticult. Univ. Sei. Agr. (Budapest) 2: 121-262 (1953). P. Aellen in Hegi, ///. FI. Mitteleur. ed. 2, 3 (2): 465-516 (1959). J. P. M. Brenan, Watsonia 4: 261-80 (1961). 1 Perianth-segments(4-)5

2 Inflorescencea terminalpanicle,theapicalpart leaflessand often spicate

3 Fruit dehiscing transversely

4 Perianth-segments enlarged in the upper part, ± spathulate, obtuse or truncate 4. retroflexus 4 Perianth-segments lanceolate or narrowly ovate or elliptic, acute

5 Longest bracteoles of the female flowers usually twice as long as the perianth 1. hybridus 5 Longest bracteoles of the female flowers 1-11 times as long as the perianth 2. cruentus 3 Fruit indéhiscent

6 Bracteoles longer than the perianth, spinescent; leaves 2-

5 cm wide, ovate or ovate-oblong 3. bouchonii 6 Bracteoles shorter than the perianth, not spinescent; leaves not more than 1 cm wide, linear-lanceolate 5. muricatus

2 Inflorescencecomposedentirelyofaxillarycymoseclusters, leafy to the apex

7 Fruit dehiscing transversely 6. blitoides

7 Fruit indéhiscent

8 Perianth-segments narrowly spathulate, erect, appressed to the fruit; leaves undulate-crenate 7. crispus

8 Perianth-segments clawed; claw erect, limb patent; leaves entire 8. standleyanus

1 Perianth-segments (2-)3 9 Fruit dehiscing transversely 10 Bracteoles twice as long as the perianth, spinescent 9. albus 10 Bracteoles not longer than the perianth, not spinescent 10. graecizans

9 Fruitindéhiscent 11 Leaves acute; stems puberulent above; fruit inflated 11. deflexus

11 Leaves ± emarginate; stems glabrous; fruit not inflated 12. lividus

1. A. hybridus L. View in CoL , Sp. Pl. 990 (1753)

( A. chlorostachys Willd. ).

Stems 20-100 cm, erect, glabrous or sparsely pubescent above. Leaves rhombic-ovate. Inflorescence elongate-spicate, often compound, with long branches. Bracteoles (2-)4-6 mm, ovate, with a very long mucro, about twice as long as the perianth. Perianth-segments narrowly ovate, usually acute, about as long as the fruit. Fruit dehiscing transversely. 2« = 32. Commonly introduced and naturalized in many parts of Europe. [Al Au Az Cr Da Ga Ge Gr Ho Hs Hu It Ju Lu Po Sm Si.] (Tropical and subtropical America.)

2. A. cruentus L. View in CoL , Syst. Nat. ed. 10, 2: 1269 (1759)

( A.patulus Bertol. ).

Like 1 but the terminal inflorescence usually dense and with short branches at the base; bracteoles 2-4 mm, with short mucro, c. 11 times as long as the perianth. 2zz= 34. Commonly introduced and naturalized, mainly in S. Europe. [Al Au Az Bu Cr Ga Ge Hs Hu It Ju Rm Rs (C, W, K, E) Sa Si.] (Tropical and subtropical America.) A. paniculatus L. , Sp. Pl. ed. 2, 1406 (1763). Very like 2 but the inflorescence red, rarely yellow or green; bracteoles 1-11 times as long as the perianth. Commonly cultivated and sometimes occurring as a casual. Probably originated in cultivation.

3. A. bouchonii Thell. View in CoL , Le Monde des Plantes 27 (nos. 45-160): 4 (1926).

Very like 1 but the bracteoles linear-lanceolate, long- spinescent; perianth-segments elliptic-lanceolate to linear; fruit indéhiscent. Naturalized in France and occurring as a casual elsewhere. [Ga Ge He.] (Origin uncertain.)