Chenopodium L.

3. Chenopodium L. 1

Annual, rarely perennial herbs, glabrous, pubescent, glandular or farinose. Leaves alternate, flat. Flowers hermaphrodite and female, usually in cymes, variously arranged. Bracteoles absent. Perianth-segm ents 2-5, m ore o r less unaltered in fruit, rarely becom ing fleshy; stamens 1-5; stigmas 2(-5). Seeds usually horizontal.

Most species grow in m an-m ade habitats and it is often impossible to decide w hether they fall into the category o f casual, established alien or native in any particular country.

T o see the m arkings on the testa, which are taxonom ically im portant, the skin-like pericarp which closely invests the ripe seed m ust be rem oved; a magnification o f x 40 is required. Literature: P. Aellen in Hegi, 77/. Fl. Mitteleur. ed. 2, 3(2): 569 et seq. (1960). P. Guinet, Jour. Agr. Trop. Bot. Appi. 6: 241-66 (1959) (seeds). T. Kow al, Polsk. Towarz. Bot. (Monogr. Bot.) 1: 87-163 (1954).

1 Ultimate branches of the axillary cymes ending in bare, subulate, spinescent points; leaves linear-oblanceolate, entire to slightly dentate 3. aristatum 1 Ultimate branches of the inflorescence neither bare and subulate nor spinescent; leaves various

2 Plant pubescent, with yellow or amber-coloured glands or glandular hairs, aromatic, not farinose

3 Inflorescence usually composed of distinct though sometimes small dichasial cymes in the axils of leaves or bracts

4 Glands on lower surface of leaves and outside of sepals very shortly stalked; sepals rounded on the back 1. botrys 4 Glands on lower surface of leaves and outside of sepals sessile; sepals each with a conspicuous longitudinal keel down the back 2. schraderanum 3 Inflorescence composed of small sessile clusters of flowers in the axils of leaves or bracts; flowers not in dichasial cymes

5 Sepals in fruit free to at least half-way down, the calyx neither saccate nor net-veined outside; inflorescence distinctly paniculate 4. ambrosioides 5 Sepals in fruit connate to near apex, the calyx saccate and net-veined outside; inflorescence not paniculate

5. multifidum 2 Plant glabrous or farinose (at least on the young parts), eglandular, not aromatic

6Perennial with triangular-hastate or -sagittate leaves; stigmas 0-8-1-5 mm; seeds vertical except in terminal flowers 6. bonus-henricus 6Annual; leaves variable but not hastate or sagittate (except 7

and 8); stigmas up to c. 0-5 mm; seeds vertical or horizontal

7 Seeds vertical except sometimes in the terminal flowers of the partial inflorescence; inflorescence glabrous

8 Leaves densely glaucous-farinose beneath 9. glaucum 8 Leaves green (or reddish) and glabrous beneath

9 Flowers in dense, globose, sessile axillary cymes along the main stems; perianth becoming fleshy and red in fruit

10 Cymes all conspicuously bracteate 7. foliosum 10 Upper cymes ebracteate 8. capitatum 9 Cymes usually in branched axillary and terminal panicles; perianth not becoming markedly fleshy and red in fruit

11 Sepals of lateral flowers of partial inflorescence scarcely ridged on back, usually free to half-way down or more 10. rubrum 11 Sepals of lateral flowers distinctly ridged or keeled on back (at least when young), connate almost to apex, forming a sac closely investing the fruit 11. botryodes 7 Seeds usually all horizontal; inflorescence sometimes glabrous, but more often farinose

12 Larger cauline leaves ± cordate to subtruncate at base, coarsely dentate; seeds 1-75-2 mm in diameter, with coarsely pitted testa 12. hybridum 12 Larger cauline leaves not cordate, ±cuneate; seeds less than 1-75 mm in diameter

13 Inflorescence-axes and outside of sepals glabrous (rarely sparsely farinose in 15)

14 Leaves entire, or rarely with a single, inconspicuous tooth on each side, ovate-elliptic, cuneate at base;

stems 4-angled 13. polyspermum 14 Leaves ± dentate, the larger ones debate; stems not

4-angled 15. urbicum 13 Inflorescence-axes and outside of sepals ± conspicuously farinose, at least when young 15 Plant smelling strongly of decaying fish; leaves entire or with a single angle on one or both sides towards base 14. vulvaria 15 Plant not evil-smelling; leaves often ± dentate or lobed

16 Seeds with acute margins; testa with minute, very close, rounded pits; leaves often strongly dentate,

not at all 3-lobed 16. murale

16 Seeds with obtuse margins; testa smooth, furrowed,

or with much larger pits than 16; leaves variable

17 Testa strongly pitted; leaves conspicuously 3-lobed

18 Middle lobe of leaves ± oblong and parallel-sided,

slightly lobed to subentire; pits on testa close and radially elongate; plant not turning red

17. ficifolium

18 Middle lobe of leaves ± triangular and acute, with a few irregular teeth; pits less deep and regular;

plant soon turning red 18. acerifolium

17 Testa not strongly pitted, usually ± smooth or furrowed; leaves 3-lobed or not

19 Leaves up to 11 x 13 cm; young parts of plant conspicuously tinged with reddish-purple

23. giganteum

19 Leaves rarely more than 6 cm; young shoots not conspicuously reddish-purple

20 Stems 5-30 cm, normally procumbent; leaves 3-

lobed (arctic Russia) 19. jenissejense

20 Stems normally erect or ascending; leaves variable

(not arctic)

21 Leaves (at least middle and lower cauline) almost or quite as wide as long; inflorescence very grey-farinose 20. opulifolium

21 Leaves (except the most juvenile) at least l j

times as long as wide; inflorescence usually not very grey-farinose

22 Plant usually deep green (though often ± masked by grey); stems often reddish; leaves usually ovate-lanceolate, dentate or entire; testa with shallow, widely spaced, radial furrows 21. album

22 Plant usually rather bright glaucescent green;

stems not red; larger cauline leaves always ovate-rhombic, with acute, forwardly directed teeth; testa with more numerous closer and deeper furrows than in 21 22. suecicum