Urtica chamaedryoides |
Urticaceae |
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heartleaf nettle, slim stingingnettle |
nettle family |
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Habit | Herbs, annual, with taproot, 1.5-8 dm. | Herbs or small shrubs [lianas, trees], herbs annual or rhizomatous perennial, usually pubescent, sometimes with stinging hairs, deciduous. | ||||||||||||||||||||||||||||||||
Stems | usually branched from base, erect or reclining. |
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Leaves | blades narrowly ovate to orbiculate, distal blades sometimes lanceolate, 2-8 × 1-6 cm, base nearly cordate to rounded, sometimes cuneate in distal leaves, margins serrate, apex rounded to acute; cystoliths rounded or ± elongate. |
blades paired, equal in size (except in Pilea, which may have unequally paired leaves), dotted with linear or rounded marks formed by cystoliths (variously shaped calcium carbonate crystals inside epidermal cells). |
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Inflorescences | ± globose cymes. |
axillary or terminal, of paniculately or racemosely arranged cymes, or spikelike. |
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Flowers | unisexual, staminate and pistillate intermixed in same inflorescence, sessile to short-pedunculate. |
bisexual or unisexual (staminate or pistillate), staminate and pistillate flowers on same or different plants; perianth hypogynous. |
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Staminate flowers | usually pedicellate; tepals 4-5, white or green; stamens 4-5, equaling tepals in number; filaments inflexed in bud, reflexing suddenly as flowers open; anthers basifixed, dehiscing by longitudinal slits; pollen ejected explosively; pistillode 1. |
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Pistillate flowers | outer tepals linear, 0.4-0.8 mm, inner tepals ovate, 1.4-2 × 1-1.4 mm. |
usually sessile; tepals 2-4, hypogynous, greenish or reddish, distinct or connate; staminodes present or absent; pistil 1, 1-locular; placentation basal; ovule1; style present or stigma sessile; stigma linear [capitate]; Bisexual flowers: tepals 4; stamens 4; pistil 1. |
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Fruits | achenes, free or loosely or tightly surrounded by persistent, accrescent perianth. |
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Achenes | ovoid to broadly ellipsoid, 1.2-1.4(-1.6) × 0.8-1 mm. |
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2n | = 26. |
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Urtica chamaedryoides |
Urticaceae |
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Phenology | Flowering all year except early winter. | |||||||||||||||||||||||||||||||||
Habitat | Rich, wooded slopes, bluffs, stream banks, swamps, waste places, and fields, often on limestone or nearly neutral soils | |||||||||||||||||||||||||||||||||
Elevation | 0-600 m (0-2000 ft) | |||||||||||||||||||||||||||||||||
Distribution |
AL; AR; FL; GA; IL; KS; KY; LA; MO; MS; NC; OH; OK; SC; TN; TX; n Mexico
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Nearly worldwide; primarily tropical and subtropical regions |
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Discussion | Genera ca. 45, species ca. 800 (8 genera, 21 species in the flora). Cystoliths cause patterns on epidermal surfaces. Forms of the cystoliths given in descriptions are readily discernible from surface patterns. Stinging hairs in Urticaceae have a distinct bulbous or cylindric base and a stiff, translucent apex. Nonstinging hairs are soft and flexible and lack a bulbous or cylindric base. The compounds producing the stinging sensation caused by contact with some members of Urticaceae have been reported to be histamine, acetylcholine, 5-hydroxytryptamine, and, in extracts from which the other three have been removed, an unknown substance that produces pain (E. L. Thurston and N. R. Lersten 1969). E. L. Thurston (1969) was not able to find these compounds in Urtica chamaedryoides using analytic techniques, but J. M. Kingsbury (1964, p. 67) reported that the same species "...contains toxicologically significant amounts of acetylcholine and histamine." The tip of the stinging hair breaks off upon slight contact, leaving a sharp point that readily pierces skin and allows fluid contents of the hair to enter flesh through the body of the hair, which acts as a miniature hypodermic needle. Economically the Urticaceae are most important for their fibers (see D. W. Woodland 1989). They can be troublesome weeds (species of Urtica and Parietaria), pot herbs (species of Pilea in the tropics, of Urtica in temperate zones), and frequently cultivated ornamentals (Pilea) (I. Friis 1993). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 3. | FNA vol. 3, p. 400. | ||||||||||||||||||||||||||||||||
Parent taxa | Urticaceae > Urtica | |||||||||||||||||||||||||||||||||
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Synonyms | U. chamaedryoides var. runyonii | |||||||||||||||||||||||||||||||||
Name authority | Pursh: Fl. Amer. Sept. 1: 113. (1814) | Jussieu | ||||||||||||||||||||||||||||||||
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