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(Last Modified On 1/25/2013)
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(Last Modified On 1/25/2013)
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Family
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AMARANTHACEAE
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Contributor
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JAMES A. DUKE
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Description
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Flowers perfect or unisexual, monoecious, polygamous or dioecious, mostly pentamerous, usually bracteate and bibracteolate, sessile or short-pedicellate. Calyx uniseriate or biseriate, commonly hypogynous; sepals (2-) 5, discrete or partially connate, scariose, whitish or variously colored. Corolla absent. Stamens (2-) 5, rarely more, hypogynous or perigynous, the filaments discrete or flattened and united below into a tube, the tube often with filamentous pseudostaminodia inserted between the filaments; anthers 2- to 4-locellate, usually introrse and dorso-medially attached. Ovary superior, unilocular, uniovulate (multiovulate in Pleuropetalum, Celosia and allied genera); ovules campylotropous on mostly elongate flattened funicles; styles 1-8; stigmata capitate or filiform. Fruit a 1-seeded utricle or rarely a several-seeded capsule, often circumscissile; seeds usually cochleate-orbiculate, the embryo excentric in a mealy endosperm. Herbs, shrubs, small trees or clambering vines with alternate or opposite mostly entire exstipulate leaves. Inflorescences of solitary flowers, spikes, glomes, glomerules, or thyrses simply, racemosely or corymbosely disposed.
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Distribution
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This largely tropical and subtropical family, of some 50 genera and 500 species, is represented in Panama by eleven of the twelve genera thus far reported for Central America. The twelfth genus, represented in Central America by Froe- lichia interrupta, has not yet been reported between Guatemala and Colombia.
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Note
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Many of the Panama species are cultivants or anthropochorous weeds of disturbed habitats. Several species in several genera are employed as potherbs and species of Amaranthus are a source of grain. Species of Iresine, Celosia, Amaranthus and Gomphrena are planted as ornamentals in Central America and other places.
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Key
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a. Leaves alternate; fruit a many-seeded capsule or a 1-seeded utricle; stigmata 2-8; anthers 4-locellate. b. Fruit a many-seeded capsule; stamens united below for nearly half their length; stigmata 2-8, usually exceeding the calyx. c. Capsules exceeding the usually deflexed sepals; seeds more than 10; stigmata 2-S, as long as or longer than the sulcate style; inflorescence paniculate or corymbose; leaves usually ovate; woodland plants...................................................................................... 1. PLEUROPETALUM cc. Capsules included by the erect sepals; seeds less than 10, stigmata 2-3, much shorter than the terete style; inflorescences of mostly simple spikes (very complex fasciated inflorescences in cultivants); leaves mostly lanceolate; cultivants or escapes (in Panama) ........... 2. CELOSIA bb. Fruit a 1-seeded utricle; stamens discrete or united below for less than a third of their length; stigmata 2-3, exserted or included. d. Flowers monoecious or polygamo-monoecious (in Panama spp.); filaments discrete; seeds exarillate, reddish brown, less than 1.5 mm. broad; erect or ascending herbs ............................... 3. AMARANTHUS dd. Flowers perfect; filaments basally connate; seeds arillate, black, 1.5-2.5 mm. broad; clambering suffruticose herbs or shrubs ........... 4. CH AMISSOA aa. Leaves opposite; fruit a 1-seeded indehiscent utricle; stigmata 1-3; anthers 2- to 4-locellate. e. Inflorescences of elongate spikes, the constituent flowers or glomerules deflexed in fruit; bracts and bracteoles strongly spinescent; anthers 4-locellate; style 1, with a capitate stigma. f. Flowers not glomerulate, perfect; spines straight or slightly arcuate; seeds 0.8-1.2 mm. broad, reddish brown; sepals glabrate or minutely tomentose, without protrusive ribs ..................................... 5. ACHYRANTHES ff. Flowers glomerulate, some sterile and highly modified; spines uncinate; seeds 1-2.5 mm. broad, succineous; sepals pilose, with strongly protrusive ribs .................................... 6. CYATHULA ee. Inflorescences of panicles, racemes, glomerules or short congested spikes, the constituent flowers not strongly deflexed in fruit; bracts rarely spinescent (Atternanthera spp.); anthers 2-locellate; styles 1-3, the stigmata filiform, cylindric or capitate. g. Inflorescences of spikes in much branched panicles (in Panama); flowers perfect, polygamous or dioecious, often with an obvious tuft of hairs arising between the bracts and sepals; stigmata 1-3, if 1, bilabiate; erect herbs, shrubs, trees or clambering vines. h. Flowers perfect; stigma 1, bilabiate; outer 3 sepals much broader than the inner, with the basal hairs borne mostly inside the outer sepals; clambering suffruticose perennials ........................ 7. PFAFFIA hh. Flowers perfect or dioecious; stigmata 2-3, filiform to deltoid; sepals subequal, the basal hairs arising mostly outside the sepals; erect herbs or shrubs (in Panama) .. .................................... 8. IRESINE gg. Inflorescences of spikes or glomes, these solitary or in trichoto- mously few-branched corymbs; flowers perfect; tufts of intrafloral hairs not obvious to the naked eye; stigmata 1-2, if 1, capitate; procumbent or erect herbs (Atternanthera spp. may be shrubby clamberers). i. Leaf bases amplexicaul, with a tuft of short hairs around the cupuliform node; stigmata 2; pseudostaminodia absent, the filament tube short or absent; flowers short-pedicellate within the bracteoles ........- .............-........ 9. PHILOXERUS ii. Leaf bases not amplexicaul, thus not forming a cup with a tuft of hairs around the node; pseudostaminodia well-developed (in Panama), the filament tube obvious; flowers sessile within the bracteoles. j. Stigma 1, capitate to short-cylindric; anthers with an obvious filament inserted between the lacerate or dentate pseudo- staminodia; bracteoles shorter than the sepals, not conspicu- ously cristate (in Panama) ............................ -------10. ALTERNANTHERA jj. Stigmata 2, filiform; anthers sessile at the summit of the filament tube between bilobate pseudostaminodia; bracteoles equaling or exceeding the sepals, cristate .............................. 11. GOMPHRENA
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