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(Last Modified On 1/14/2013)
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(Last Modified On 1/14/2013)
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Family
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POLYGONACEAE
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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 or dioecious, trimerous or dimerous, on short usually articulate pedicels, solitary or fasciculate within scariose ochreolae. Calyx uniseriate or biseriate, hypogynous, of 3-6 free or partially connate tepals. greenish to red or white. Stamens usually 6-9, rarely more or less, the filaments filiform or flattened, occasionally partially adnate to the calyx; anthers 2- or 4- locular, usually versatile and introrse. Ovary superior, triquetrous or lenticular, unilocular, containing a single erect orthotropous ovule, the stigmata filiform or capitate and entire or variously fringed. Achene trigonous or lenticular, usually with a crustaceous pericarp, the embryo usually excentric in a mealy endosperm. Herbs, shrubs, trees or vines with alternate usually entire simple leaves with ochreate stipules, the stems often sulcate, hollow and geniculate. Flowers in terminal racemes or panicles, often spicate, rarely cymose, or solitary or fasciculate in the axils, usually subtended by scariose ochreolae.
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Note
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This predominantly north temperate family of about 30 genera and 700 species is represented in Panama by six genera. It is economically a rather unimportant family. Fagopyrum, the buckwheat, and Rheum, the rhubarb, are crops of limited importance. Antigonon spp., Polygonum spp. and Muehlenbeckia spp. are often cultivated in Central America as ornamentals. Some species of Rumex are troublesome lawn weeds.
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Key
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a. Plants herbaceous or suffruticose (spp. of Polygonum ? TINARIA twin- ing); calyx of 3-6 tepals, the inner slightly larger; stamens 5-9. b. Calyx of 6 tepals, the outer reflexed or spreading, the inner usually larger and longitudinally folded, often tuberculate; flowers perfect or dioecious, verticillate; filaments shorter than the anthers - 1. RUMEX bb. Calyx of 3-5 subequal tepals, not reflexed, closely conforming to the achene, not plicate or tuberculate; flowers perfect, not verticillate; filaments longer than the anthers. - 2. POLYGONUM aa. Plants shrubby, arboreal or lianoid; calyx of 5-6 tepals, the outer slightly or greatly larger than the inner; stamens mostly 8-9. c. Achenes scarcely if at all exceeded by the tepals; tepals discrete and scariose or showing tendencies to form a fleshy calyx tube fused with the achene; tepals 5, the outer only slightly larger than the inner; stamens 8. d. Flowers perfect; tepals cordate, discrete, becoming scariose, loosely investing the achene; vines with tendrils. -. 3. ANTIGONON dd. Flowers dioecious or polygamo-dioecious (perfect in Muehlen- beckia spp.); tepals not cordate, bony to fleshy but not scariose, closely investing the achene; trees, shrubs or scramblers without tendrils. e. Inflorescences both axillary and terminal, dioecious or perfect; tepals discrete nearly to their base; scramblers (in Panama), the twigs terete to quadrangulate, not lenticular. -4. MUEHLENBECKIA ee. Inflorescences terminal on primary or short lateral branches, dioecious with staminodes or pistillodes developed; tepals forming a dry to fleshy tube, at least at their bases; trees in Panama (except one scrambler with bilateral wood and lenticular twigs). 5. COCCOLOBA cc. Achenes conspicuously exceeded by 3 wing-like outer tepals; outer tepals of the pistillate flowers basally fused to form a tube free of the achene; tepals 6, the outer much longer and broader than the inner in pistillate flowers; stamens 9-........................... . 6. TRIPLARIS
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