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Amaranthaceae
See list of 19 genera in this familyReference: Clemants (1992).
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1a. Leaves opposite
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2b. Stems not appearing jointed; leaves neither connate nor scale-like; flowers not arranged in groups of 3, not sunken into the stem
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3a. Flowers unisexual; stems and inflorescence glabrous or farinose, but not pubescent; leaves glabrous or farinose, but not pubescent; filaments distinct; fruits concealed by a pair of accrescent bracteoles [Fig. 323]; leaf blades entire or, more commonly, toothed or with a pair of lobes near the base [Fig. 325] (in part)
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3b. Flowers bisexual; stems sparsely to densely villous or villous-tomentose; leaves pubescent on one or both surfaces (at least on the abaxial midrib); filaments connate (at least at the base); fruits not concealed by a pair of accrescent bracteoles (though often concealed by the persistent perianth); leaf blades entire
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4a. Spikes 20–28 mm in diameter, white, yellow, red, or purple, showy; style terminated by 2 subulate or filiform stigmas; plants annual, from fibrous roots
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4b. Spikes 6–8 mm in diameter, mainly white or gray to white-green or gray-green, not especially showy; styles terminated by a single capitate stigma or the stigma minutely 2-lobed; plants annual with a taproot or perennial
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5a. Filaments monadelphous, the connate tube suggesting a gamopetalous corolla; leaf blades linear to narrow-lanceolate; rachis of inflorescence moderately to densely villous-tomentose; calyx segments ± monomorphic; plants annual
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5b. Filaments connate only at the very base; leaf blades obovate to orbicular; rachis of inflorescence glabrous or sparsely pubescent; calyx segments polymorphic—the outer 2 longest and spine-tipped, the next inner shorter and narrower, the inner 2 shortest and with hairs along the abaxial keel; plants perennial
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1b. Leaves alternate or all basal
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6a. Sepals usually dry and scarious; filaments distinct or, more commonly, connate near the base; ovary with 3 stigmas (often only 2 in A. palmeri) [Fig. 318]
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7a. Flowers unisexual; utricle 1-seeded; inflorescence not fasciated
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7b. Flowers bisexual; utricle 6- to 10-seeded; inflorescence fasciated
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6b. Sepals membranaceous to herbaceous (hyaline in Axyris); filaments distinct; ovary with 2 (–5) stigmas
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8a. Leaves stellate-pubescent on the abaxial surface; sepals hyaline; fruit obovate in outline, with a bilobed wing at the apex
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8b. Leaves glabrous, farinose, or pubescent, but not stellate-pubescent; sepals usually pigmented; fruit orbicular to obovate or oblong in outline, without a bilobed wing at the apex
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9a. Plants monoecious or dioecious (i.e., flowers unisexual); fruit or seed concealed by a pair of accrescent bracteoles [Fig. 323]
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10a. Stigmas 2; herbage glabrous or sparsely to densely farinose (in part)
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10b. Stigmas 4 or 5; herbage glabrous
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9b. Plants synoecious (i.e., with bisexual flowers only) or sometimes polygamous (i.e., with bisexual and unisexual flowers); fruit visible or concealed by a persistent calyx, the bracteoles not accrescent
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11a. Leaf blades linear to narrow-lanceolate or oblanceolate in outline, entire, sessile or subsessile (with obscure petioles up to 3 mm long in Kochia) [Fig. 338]
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12a. Leaves tipped with spines (especially those from the upper portion of the stem)
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13a. Flowers with usually 2 styles and 5 stamens; fruits globose to ovoid, with a horizontally oriented seed
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13b. Flowers with usually 5 styles and 3 stamens; fruits compressed, with a vertically oriented seed
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12b. Leaves not tipped with spines, at most pointed
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14a. Stems, leaves, and/or perianth villous or short-pilose with eglandular hairs
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15a. Fruiting sepals with a prominent, transverse wing on the abaxial surface
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15b. Fruiting sepals without a wing, with either conical tubercles or hooked spines on the abaxial surface [Fig. 327]
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14b. Plants glabrous or farinose or stipitate-glandular in Dysphania
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16a. Leaves terete to planoconvex in cross-section; flowers borne in groups of 1–7, usually 3, in the axils of the leaves
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16b. Leaves flat, at least in the basal portion; flowers borne variously, but not consistently in groups of 3
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17a. Plants glabrous or farinose, but not glandular (in part)
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17b. Plants with stipitate glands or subsessile glands (in part)
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11b. Leaf blades oblong or lanceolate to ovate or triangular, entire, toothed, or lobed, at least the lower ones petioled (caution: the lower leaves in some Chenopodium and often all the leaves in Cycloloma deciduous by fruiting) [Fig. 329]
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18a. Fruiting perianth with a continuous, transverse wing; inflorescence a diffusely branched panicle with solitary flowers at each node
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18b. Fruiting perianth lacking a horizontally oriented wing; inflorescence usually either a panicle with spike-like branches or of axillary clusters of flowers, the flowers occurring singly or in glomerules at each node
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19a. Ovary semi-inferior; roots moderately to strongly swollen, dark red, yellow, or white
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19b. Ovary superior; roots not swollen, usually pale or brown
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20a. Calyx composed of 1 sepal, not enclosing the fruit at maturity; androecium composed of 1 stamen
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20b. Calyx composed of 3–5 sepals, enclosing and often somewhat concealing the fruit at maturity; androecium composed of 1–5 stamens, commonly 5
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21a. Plants glabrous or farinose, but not glandular (in part)
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21b. Plants with stipitate glands or subsessile glands (in part)
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Each photo represents one genus in this family.