Chenopodium

Herbs, annual or perennial [rarely suffruticose, or small trees], farinaceously pubescent with small white inflated hairs or glabrous. Stems erect to prostrate, branched (rarely simple), not jointed, not armed, not fleshy. Leaves alternate, petiolate or sessile, not fleshy; blade linear, oblong, lanceolate, ovate, triangular, trullate, or rhombic, flattened, not jointed, not spinose, base truncate, cordate, hastate, or cuneate, margins entire, dentate, sinuate, or serrate, apex acute to acuminate or obtuse, occasionally lobed. Inflorescences spicate and terminal or axillary glomerules; bracts usually absent or leaflike but narrower than leaves. Flowers bisexual (rarely unisexual, then terminal flower male or bisexual and lateral flowers female), bracteoles absent; perianth segments (3–)5, usually connate at base, sometimes almost to middle or beyond, not imbricate, rounded or keeled abaxially, wings and spines absent; stamens 5 or fewer; ovary superior; style 1 or absent; stigmas 2(–5), filiform. Fruits utricles or achenes, often enclosed in infolded perianth, indehiscent or irregularly dehiscent; pericarp membranaceous or chartaceous, adherent or nonadherent. Seeds horizontal or vertical [rarely oblique], lenticular to subglobose; seed coat black, brown-black, or reddish brown; embryo annular or hippocrepiform (horseshoe-shaped), surrounding copious farinaceous perisperm; radicle inferior or centrifugal. x = 9.

Distribution

Worldwide.

Discussion

Species 100+ (34 in the flora).

Chenopodium quinoa Willdenow (quinoa) is cultivated occasionally as a grain crop. It will key to Chenopodium berlandieri and is related to it. It generally has larger leaves and inflorescences and light-colored seeds.

Seeds are generally flattened and lentil-like. The equatorial edge (here called margin) may be rounded, flattened, or grooved. The surface is usually honey combed or smooth. All leaf characteristics refer to primary, well-developed leaves; those often fall early, however, so smaller, upper leaves often are shorter, narrower, and less lobed.

Selected References

Aellen, P. 1929. Beitrag zur Systematik der Chenopodium-Arten Amerikas. Verwiegend auf Grund der Sammlung des United States National Museum in Washington, D.C. Repert. Spec. Nov. Regni Veg. 26: 31–64, 119–160.

Bassett, I. J. and C. W. Crompton. 1982. The genus Chenopodium in Canada. Canad. J. Bot. 60: 586–610.

Mosyakin, S. L. 1993. An outline of a system for Chenopodium L. (species of Europe, North and Central Asia). Ukrayins’k. Bot. Zhurn. 50: 71–77.

Mosyakin, S. L. and S. E. Clemants. 1996. New infrageneric taxa and combinations in Chenopodium L. (Chenopodiaceae). Novon 6: 398–403.

Aellen P. and T. Just. 1943. Key and synopsis of the American species of the genus Chenopodium L. Amer. Midl. Naturalist 30: 47–76.

Wahl, H. A. 1954. A preliminary study of the genus Chenopodium in North America. Bartonia 27: 1–46.

Lower Taxa

Chenopodium subg. Blitum, Chenopodium subg. Chenopodium

Key

1	Seeds vertical or both horizontal and vertical; leaf blades glabrous or occasionally farinose (C. glaucum, C. macrospermum) [7a. Chenopodium subg. Blitum]	> 2
1	Seeds all horizontal; leaf blades usually farinose [7b. Chenopodium subg. Chenopodium, 7b.2 Chenopodium sect. Chenopodium and 7b.1 sect. Grossefoveata]	> 9
2	Perianth segments 5; plants perennial [7a.1. Chenopodium sect. Agathophytum]	> 3
2	Perianth segments usually 3; plants annual	> 4
3	Leaf blade margins entire	Chenopodium bonus-henricus
3	Leaf blade margins sinuate-dentate	Chenopodium californicum
4	Leaf blades lanceolate or oblong, glaucous abaxially [7a.5 Chenopodium sect. Glauca]	Chenopodium glaucum
4	Leaf blades triangular or rhombic, rarely lanceolate, green abaxially	> 5
5	Leaf blades farinose abaxially [7a.3. Chenopodium sect. Degenia]	Chenopodium macrospermum
5	Leaf blades glabrous abaxially	> 6
6	Glomerules 3-10 mm diam., sessile on unbranched terminal and occasionally axillary spikes; perianth segments fleshy, red at maturity (not fleshy but often red in C. capitatum var. parvicapitatum); seeds all vertical [7a.2. Chenopodium sect. Blitum]	> 7
6	Glomerules 2-5 mm diam., sessile on lateral branched spikes; perianth segments membranaceous, green at maturity; horizontal and vertical seeds both present [7a.4. Chenopodium sect. Pseudoblitum]	> 8
7	Glomerules not subtended by leaflike bracts in distal 1/2 of spike; flow- ers maturing uniformly from apex of plant to base	Chenopodium capitatum
7	Glomerules subtended by leaflike bracts throughout inflorescence; flow- ers maturing from base of plant to apex	Chenopodium foliosum
8	Perianth segments connate nearly to tip	Chenopodium chenopodioides
8	Perianth segments mostly connate only at very base	Chenopodium rubrum
9	Flowers individually disposed in panicles; leaf blades glabrous	> 10
9	Flowers in loose or dense glomerules; leaf blades usually farinose [7b.2. Chenopodium sect. Chenopodium]	> 11
10	Leaves sinuate-dentate; seeds 1.3-1.9 mm diam. [7b.1. Chenopodium sect. Grossefoveata]	Chenopodium simplex
10	Leaves entire; seeds 0.8-1.3 mm diam. [7b.2a. Chenopodium subsect. Polysperma]	Chenopodium polyspermum
11	Primary leaves linear, linear-lanceolate, or occasionally narrowly oblong-ovate, 2-3 times longer than broad or longer; usually without teeth or lobes or occasionally with a pair of basal lobes [7b.2d. Chenopodium subsect. Leptophylla and 7b.2b. Chenopodium subsect. Chenopodium (33. C. strictum)]	> 12
11	Leaves ovate, rhombic, triangular, or lanceolate, to 2 times longer than broad; usually with basal lobes and often with additional teeth on margin	> 22
12	Leaves with 1 vein, blades linear, usually somewhat fleshy, margins entire	> 13
12	Leaves with 3 veins from base, blades linear, lanceolate, or occasionally narrowly oblong-ovate or triangular-rhombic, usually without teeth or lobes or occasionally with a pair of basal lobes	> 16
13	Fruit an utricle, pericarp separable; plant mostly not farinose	Chenopodium subglabrum
13	Fruit an achene, pericarp attached; plant mostly farinose	> 14
14	Sepals connate to or above widest part of seed; seeds 1.3-1.5 mm diam., margins acute	Chenopodium cycloides
14	Sepals connate only at very base; seeds 0.8-1.5 mm diam., margin srounded	> 15
15	Seeds 1.4-1.6 mm diam.; well-grown plants more than 4 dm	Chenopodium pallescens
15	Seeds 0.9-11.1 mm diam.; plants chiefly less than 4 dm	Chenopodium leptophyllum
16	Leaves 3 times longer than broad or longer	> 17
16	Leaves 2-3 times longer than broad, usually narrowly oblong-ovate or deltoid rhombic	> 20
17	Fruit an achene, pericarp attached, minutely granular-roughened; seeds flattened on top	Chenopodium hians
17	Fruit an utricle, pericarp separable; seeds rounded on top	> 18
18	Perianth spreading from fruit at maturity; plants strictly erect	Chenopodium pratericola
18	Perianth enclosing fruit at maturity; plants erect to spreading	> 19
19	Plants usually spreading; perianth segments obtuse; leaf blades usually unlobed	Chenopodium desiccatum
19	Plants erect; perianth segments acute; leaf blades often with basal lobes	Chenopodium foggii
20	Fruit an utricle, pericarp separable; leaf blades entire	Chenopodium atrovirens
20	Fruit an achene, pericarp attached; leaf blades often toothed	> 21
21	Leaves with 3 prominent veins, sparsely farinose; seeds 0.7-0.8 mm diam	Chenopodium nevadense
21	Leaves with one prominent vein and two obscure outer veins at the base, moderately farinose; seeds 0.9-1.5 mm diam.	Chenopodium strictum
22	Seeds honeycomb-pitted [7b.2f. Chenopodium subsect. Favosa]	> 23
22	Seeds smooth or areolate	> 26
23	Lower leaves entire or with only 1-2 teeth or lobes near base	> 24
23	Lower leaves serrate and usually lobed	> 25
24	Seeds subglobose, entirely covered by perianth segments at maturity; pericarp slightly to prominently whitened; leaves broadest very near base	Chenopodium watsonii
24	Seeds more or less flattened, partially exposed at maturity; pericarp black; leaves usually prominently lobed above the base	Chenopodium neomexicanum
25	Leaves with central lobe 2-3 times longer than lateral lobe	Chenopodium ficifolium
25	Leaves with central lobe only slightly longer than lateral lobes or unlobed and merely toothed	Chenopodium berlandieri
26	Leaves triangular	> 27
26	Leaves ovate to broadly ovate, rhombic, or lanceolate, variously lobed or toothed	> 30
27	Leaf blades toothed and sometimes with basal lobes, usually glabrous	> 28
27	Leaf blades with basal lobes but no additional teeth, usually farinose [7b.2e. Chenopodium subsect. Fremontiana]	> 29
28	Seeds 0.8-1.2 mm diam, seed margin round; leaf blades often with basal lobes [7b.2b. Chenopodium subsect. Urbica]	Chenopodium urbicum
28	Seeds 1-1.5 mm diam., seed margin acute; leaf blades without basal lobes [7b.2c. Chenopodium subsect. Undata]	Chenopodium murale
29	Plants simple below, branching above; seeds 1-1.3 mm diam.	Chenopodium fremontii
29	Plants profusely branching from base; seeds 0.9-1.1(-1.2) mm diam	Chenopodium incanum
30	Leaf blades without teeth except for often present basal lobes or teeth	> 31
30	Leaf blades with lateral teeth and often basal lobes	> 35
31	Flowers in markedly different stages of development in the same glom- erules [7b.2g. Chenopodium subsect. Standleyana]	Chenopodium standleyanum
31	Flowers all more or less in same stages of development in same glomerules	> 32
32	Leaves without basal lobes or teeth, malodorus [7b.2b. Chenopodium subsect. Chenopodium]	Chenopodium vulvaria
32	Leaf blades with basal lobes; not malodorous	> 33
33	Fruit an achene, pericarp attached [7b.2e. Chenopodium subsect. Fremontii]	Chenopodium nevadense
33	Fruit an utricle, pericarp separable	> 34
34	Plants 0.1-0.7 m [7b.2d. Chenopodium subsect. Leptophylla]	Chenopodium atrovirens
34	Plants 0.5-1.2 m [7b.2e. Chenopodium subsect. Fremontii]	Chenopodium albescens
35	Leaves widely ovate, as long as broad; lateral lobes equaling terminal lobes in size	Chenopodium opulifolium
35	Leaves ovate, rhombic, or lanceolate, longer than broad; lateral lobes when present smaller than the terminal lobe	> 36
36	Leaf margins tapering to an acute apex; leaves ovate, rhombic, or lanceolate; inflo- rescence branched spicate or cymose	Chenopodium album
36	Leaf margins more or less parallel below the obtuse apex, leaves lanceolate to narrowly elliptic; inflorescence normally moniliform, not profusely branching	Chenopodium strictum