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(Last Modified On 1/14/2013)
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(Last Modified On 1/14/2013)
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Genus
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POLYGONUM L.
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PlaceOfPublication
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Sp. P1. 359. 1753.
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Description
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Flowers perfect, occasionally with tendencies toward suppression of one sex, with pedicels distally -articulated, usually in ochreolate fascicles. Perianth of 4-5 subequal partially connate tepals, white, green, red or pink. Stamens 5-8 (-9), the filaments discrete, often unequal in length, occasionally adnate to the tepals, the anthers small, versatile, introrse, often isodiametric and appearing peltate. Ovary lenticular or trigonous; styles 2 or 3, terminated by capitate stigmata. Achene usually included, lenticular or trigonous, often beaked, the facies ovate or orbicular. Annual or perennial herbs, sometimes clambering or twining, occasionally shrubby. Leaves alternate, mostly linear to ovate, occasion- ally sagittate, cordate or hastate, the blades mostly exceeding the petioles; ochreae usually conspicuous, often fringed with strigose cilia. Inflorescences of terminal spicate panicles, racemes or cymes, in some species the flowers solitary or fasciculate in the axils; rhachises glabrous to sericeous, occasionally glandular.
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Distribution
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This largely temperate genus contains about 150 species, about half of which occur in North America.
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Note
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Many of the herbaceous species are aquatic or bog plants; some are rather obnoxious weeds. Shrubby species are often cultivated as ornamentals. The sections of the genus have often been elevated to generic status, but they are here maintained at the subgeneric level. Heterostyly, tendencies toward the suppression of one sex in the flowers, environmental modifications, and hybridization have all contributed to the difficult taxonomy of the section PER- SICARIA, to which belong five of the isix Panama species. Fourteen species are known from Guatemala and four from Costa Rica.
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Key
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a. Plants not twining; leaf bases acute; inflorescences of terminal sub- spicate racemes or panicles; achenes lenticular or triquetrous; styles 2-3, partially discrete ............................ ? PERSICARIA. b. Ochreae with reflexed or spreading herbaceous flanges; leaves mostly over 4 cm. wide; achenes lenticular ........-1. P. HISPIDUM bb. Ochreae unflanged, but often strigose-ciliate at the summit; leaves mostly less than 4 cm. wide; achenes lenticular or triquetrous............. c. Achenes triquetrous; styles 3; spikes filiform, lax, interrupted, with only the uppermost ochreolae imbricate. d. Tepals, leaves and ochreae conspicuously dark-punctate; midribs of the leaves subglabrous ........ 2. P. PUNCTATUM dd. Tepals, leaves and ochreae inconspicuously pellucid-punctate; midribs of the leaves strigose or strigillose ..................................... 3. P. HYDROPIPEROIDES cc. Achenes lenticular; styles 2; spikes: cylindric, rigid, continuous, with all but the lowermost ochreolae imbricate. e. Facies of the achenes ovate; ochreae 2-3 cm. long, with apical strigose cilia to 1.5 cm. long; peduncles glandless; calyx white; leaves often conspicuously pubescent 4. P. ACUMINATUM ee. Facies of the achenes orbicular; ochreae 0.5-1.5 cm. long, eciliate at the summit; peduncles glandular; calyx pink; leaves, except for the veins, glabrous ........................................................ 5. P. MEXICANUM aa. Plants twining; leaf bases cordate; inflorescences of lax axillary, fre- quently leafy, racemes or panicles; achenes triquetrous. Styles 3, united and capped by a 3-lobed capitate stigma ............................. ? TINARIA. 6. P. CONVOLVULUS
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