Herbs or suffrutescent shrubs, sometimes succulent, 2360 species in 169 genera.Shrubs (usually), or herbs. ‘Normal’ plants. Plants succulent (occasionally, if the halophytic Hemichroa is referred here rather than to Chenopodiaceae), or non-succulent (mostly). With a basal aggregation of leaves (occasionally, e.g. in Ptilotus), or with neither basal nor terminal aggregations of leaves (usually). Self supporting, or climbing (occasionally). Leaves alternate, or opposite; ‘herbaceous’ (mostly), or fleshy (perhaps only Hemichroa); sheathing, or non-sheathing; simple. Lamina entire; one-veined, or pinnately veined. Leaves exstipulate. Lamina margins entire.
Distribution
Tropical and subtropical (Africa, America, SE-Asia), temperate regions.
Floral characters
inflorescences determinate, terminal and axillary, flowers bisexual or sometimes unisexual (then monoecious or dioecious), radial, associated with fleshy to dry, papery bracts and /or braclets, and often densely clustered, tepals 3-5,, distinct to slightly connate, green and herbaceous or fleshy, to white or reddish, dry, papery, imbricate. Stamens 3-5, filaments distinct, slightly to strongly connate, anthers 1-2 locular, carpels 2-3, connate. Ovary usually superior; Stigmas 1-3, elongate to capitate. Ovules 1 to few, usually campylotropous
Leaf characters
alternate or opposite, simple, entire or undulate, sometimes serrate or lobed, with pinnate venation, but veins often obscure,, sometimes succulent. Abaxial epidermis not papillose. Adaxial hypodermis absent. Main veins embedded. Minor leaf veins without phloem transfer cells (Amaranthus, Celosia).
Stipules
absent
Fruit characters
Usually achene, utricle or capsule, usually associated with persistent fleshy to dry, perianth and/or braclets.Fleshy, or non-fleshy; dehiscent, or indehiscent; a capsule, or capsular-indehiscent, or a berry, or a drupe, or a nut (often a utricle or nutlet); without fleshy investment. Capsules circumscissile (commonly), or splitting irregularly. Seeds non-endospermic (strictly speaking). Perisperm present (abundant, mealy). Seeds with starch. Embryo well differentiated. Cotyledons 2. Embryo achlorophyllous (1/1); curved. The radicle dorsal. Testa smooth (usually shiny).
Glands
present
Hairs
present, simple to branched
Latex
absent
Uses
widely cultivated as garden ornamentes (Celosia spp. etc.) , and a few potherbs and vegetables (Amaranthus spp.).
Chemical characters
betalains present, essential amino-acids, saponins.Cyanogenic, or not cyanogenic. Alkaloids present, or absent. Iridoids not detected. Proanthocyanidins absent. Flavonols present, or absent; when present, quercetin. Ellagic acid absent (4 species, 4 genera). Betalains present. Saponins/sapogenins present, or absent. Plants often accumulating free oxalates. Inulin not found. C3 and C4, or C3-C4 intermediate. C3 physiology recorded directly in Aerva, Achyranthes, Alternanthera, Arthraerua, Celosia, Digera, Pupalia. C4 physiology recorded directly in Achanthochiton, Aerva, Alternanthera, Amaranthus, Brayulinea, Froelichia, Gomphrena, Gossypianthes, Guillemenia, Lithophila, Tidestromia. C3-C4 intermediacy in Alternanthera ficoides and A. tenella. Anatomy C4 type (Acnidia, Achyranthes, Achanthochiton, Aerva, Alternanthera, Amaranthus, Brayulinea, Celosia, Froelichia, Gomphrena, Pfaffia, Tidestromia, etc.), or non-C4 type (Achyranthes, Alternanthera, Celosia, Centemopsis, Dasysphaera, Digera, Pupalia, Sericicomopsis etc.).
