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Key to Chenopodium

Chenopodiaceae

Chenopodium

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1 Seeds arranged vertically or both horizontally and vertically in the fruit; leaf blades glabrous or occasionally sparsely farinose.
  2 Perianth segments 5; plants perennial; [Blitum, sect. Blitum]
  2 Perianth segments 3; plants annual.
    3 Leaves lanceolate or oblong, glaucous on the lower surface; [Oxybasis, sect. Pseudoblitum]
    3 Leaves triangular or rhombic, green or white-farinose on the lower surface.
      4 Leaves farinose on the lower surface; [Oxybasis, sect. Oxybasis]
      4 Leaves glabrous and green on the lower surface.
        5 Glomerules 3-10 mm in diameter, borne sessile on unbranched terminal and occasionally axillary spikes; perianth segments fleshy and red at maturity; [Blitum, sect. Blitum]
        5 Glomerules 2-5 mm in diameter, borne sessile on lateral branched spikes; perianth segments membranaceous, green at maturity; [Oxybasis, sect. Pseudoblitum]
1 Seeds arranged horizontally in the fruit; leaf blades usually farinose.
          6 Flowers individually disposed in panicles; leaf blades glabrous; [Chenopodiastrum, sect. Grossefoveata]
          6 Flowers in loose or dense glomerules; leaf blades usually farinose; [subgenus Chenopodium, section Chenopodium].
             7 Primary leaves linear, linear-lanceolate, at least 2-3× as long as wide, usually untoothed and unlobed (but often with 2 basal lobes in C. foggii); [subsection Leptophylla].
               8 Leaves 1-veined, linear.
                 9 Seeds 0.9-1.1 mm in diameter; taller plants often < 4 dm tall
                 9 Seeds 1.4-1.6 mm in diameter; taller plants > 4 dm tall
               8 Leaves 3-veined from base, linear to lanceolate or narrowly oblong-ovate or triangular-rhombic.
                   10 Leaves 2-3× as long as wide
                   10 Leaves > 3× as long as wide.
                     11 Perianth spreading from fruit at maturity; plants strictly erect
                     11 Perianth enclosing the fruit at maturity; plants erect to spreading.
                       12 Plants usually spreading; perianth segments obtuse; leaf blades usually unlobed
             7 Primary leaves ovate, rhombic, triangular, or lanceolate, usually with basal lobes and often also with additional teeth on the margins.
                          13 Seeds honeycomb-pitted; [subsection Favosa].
                            14 Seeds 1.2-2.0 mm in diameter.
                              15 Style bases with yellow area; seeds 1.2.1.5 mm in diameter
                              15 Style bases without yellow area; seeds 1.3-2.0 mm in diameter.
                                16 Inflorescences large and drooping; seeds 1.7-2.0 mm in diameter
                                16 Inflorescences small and erect; seeds 1.3-1.9 mm in diameter
                            14 Seeds 1.0-1.3 mm in diameter.
                                  17 Leaves rhombic-triangular, usually without basal lobes; inflorescences becoming bractless
                                  17 Leaves 3-lobed; inflorescences with or without bracts.
                                    18 Inflorescences bractless
                                    18 Inflorescences with leafy bracts
                                       19 Style bases without yellow area
                                       19 Style bases with yellow area
                          13 Seeds smooth or areolate.
                                         20 Leaves triangular.
                                           21 Leaf blades with basal lobes but no additional teeth, usually farinose; [subsect. Fremontiana]
                                             22 Plants simple below, branching above; seeds 1-1.3 mm in diameter
                                             22 Plants profusely branching from base; seeds 0.9-1.1(-1.2) mm in diam.
                                           21 Leaf blades toothed and sometimes with basal lobes, usually glabrous.
                                               23 Seeds 1.0-1.5 mm in diameter, the seed margin sharp; leaf blades without basal lobes; [Chenopodiastrum, sect. Chenopodiastrum]
                                               23 Seeds 0.8-1.2 mm in diameter, the seed margin rounded; leaf blades often with basal lobes; [Oxybasis, sect. Urbica]
                                         20 Leaves ovate to broadly ovate, rhombic, or lanceolate, variously lobed or toothed.
                                                 24 Leaf blades without teeth, except for the often present basal lobes or teeth.
                                                    25 Leaves not aromatic; flowers in each glomerule in markedly different stages of development; [subsection Standleyana]
                                                    25 Leaves strongly malodorous; flowers in each glomerule in similar stages of development; [subsection Chenopodium]
                                                 24 Leaf blades with lateral teeth and often basal lobes; [subsection Chenopodium].
                                                      26 Leaves widely ovate, 1× as long as wide; lateral leaf lobes as large as the terminal lobe
                                                      26 Leaves ovate, rhombic, or lanceolate, >1× as long as wide; lateral leaf lobes smaller than the terminal lobe (or absent).
                                                        27 Leaf margins more or less parallel below the obtuse apex; leaves lanceolate to narrowly elliptic; inflorescence generally moniliform, not profusely branched; seeds oval in outline; pericarp strongly adherent
                                                        27 Leaf margins tapering to an acute apex; leaves ovate, rhombic, or lanceolate; inflorescence branched (spicate or cymose); seeds circular in outline; seed pericarp non-adherent.
                                                          28 Plants greenish-gray, copiously farinose; perianth parts yellow-farinose, ribbed but not keeled
 Chenopodium album var. stevensii
                                                          28 Plants green, slightly farinose; perianth parts green to slightly farinose, with a keeled midrib.
                                                            29 Plant sparsely branched, with an erect habit; inflorescences in paniculate spikes; lower leaves lobed or toothed; upper leaves triangular and toothed
                                                            29 Plant densely branched from base; inflorescences in paniculate arching branches; lower leaves with a few lobes or teeth; upper leaves lanceolate and entire