The World Flora Online

6. Potamogeton perfoliatus L., Sp. Pl. 126 (1753). Lectotipo (designado por Haynes, 1986): Suecia-Finlandia, Linnaeus s.n. (Institut de France, Paris).

Por A. Novelo R. y A. Lot H.

Potamogeton bupleuroides Fern., P. perfoliatus var. bupleuroides (Fern.) Farw.

Tallos erectos c. 1 mm de diámetro, delgados, sin glándulas en los nudos. Hojas siempre sumergidas, con la base envolviendo al tallo; estípulas 3.5-6.5 cm, libres, caducas; láminas 0.9-7 x 1.7-4 cm, homomorfas, lanceoladas a ovadas, el ápice redondeado, los márgenes enteros. Inflorescencia con 3-9 verticilos de flores, cilíndrica, compacta; pedúnculos 1-5 cm x hasta 1.5 mm, igual o más gruesos que el tallo. Tépalos 0.7-1.5 mm de ancho; anteras 1-1.2 mm. Aquenios 1.6-3 x 1.3-2 mm, orbiculares, dorsalmente lisos; pico estilar 0.1-0.7 mm, persistente. Ríos y lagos de agua dulce. G (Bernoulli s.n., K). 0-1800 m. (E. Canadá a Louisiana y Guatemala, Europa.)

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Plants perennial, submerged in fresh water. Rhizome unspotted, terete, slender. Stems terete, 0.5-2.5 mm in diam., densely branched at upper part. Stipules axillary, convolute, 3-22 mm, membranous, evanescent; leaves sessile, lanceolate to broadly ovate, orbicular-ovate, or ovate-oblong, 3-5-veined, with narrow rows of lacunae bordering midvein, base cordate and amplexicaul, margin minutely denticulate, apex obtuse or rounded. Spikes usually contiguous and cylindric, with 4-7 whorls of opposite flowers; peduncles 2-11 cm. Carpels 4. Fruit obovoid, 2.5-4.5 mm, abaxial keels 3, with a slightly sharp midvein and 2 indistinct lateral keels, with a short beak at tip. Fl. and fr. May-Oct. 2n = 52.

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• 2
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Rhizomes present. Cauline stems terete, without spots, to 250 cm; nodal glands absent. Turions absent. Leaves submersed, ± spirally arranged, sessile, lax; stipules deteriorating into fibers and deciduous, inconspicuous (absent on proximal portion of stem), convolute, free from blade, light brown to green, not ligulate, 3.5--6.5 cm, not fibrous, not shredding at apex; blade olive-green, broadly lanceolate, orbiculate, or ovate, not arcuate, 0.9--7.6(--9.7) cm ´ 7--40 mm, base rounded, without basal lobes, clasping, margins entire, often crispate, apex not hoodlike, not splitting when pressed, round, rarely acute; veins 3--25. Inflorescences unbranched, emersed; peduncles not dimorphic, terminal or axillary, erect to rarely recurved, cylindric, 1--7.3 cm; spike not dimorphic, cylindric, 0.4--4.8 cm. Fruits sessile, greenish brown to olive-green, obovoid, turgid or rarely concave, not abaxially or laterally keeled, 1.6--3 ´ 1.3--2.2 mm; beak erect, 0.4--0.6 mm; sides without basal tubercles; embryo with 1 full spiral. 2n = 52.

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Stem slender, to 2.5 mm, often much branched; internodes mostly 1–3 cm; lvs all submersed, ovate to suborbicular, 1–5(–9) cm × 5–25(–40) mm, mostly broadly rounded or obtuse, sessile, with cordate-clasping, often perfoliate base, delicately 3–25-veined, 3(5) veins stronger; stipules axillary, free, evanescent; peduncles 1–7 cm, about as thick as the stem, not clavate; spikes dense, cylindric, 1–4.5 cm; frs obliquely obovoid, 1.6–3 mm (including the short beak), very shallowly pitted, with 3 obscure dorsal keels, or keelless; 2n=52. Ponds and slow streams; irregularly cosmopolitan, in Amer. from Nf. and Ont. to N.C. and O., disjunct along the Gulf Coast.

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• 6
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Rhizomes present; erect stems terete, without spots, to 2.5 m. Leaves sessile, submersed, ± spirally arranged, lax, entire to crisped, usually olive-green, broadly lanceolate, orbicular, or ovate, nonarcuate, 3-25-veined, 0.9-7.6(-9.7) x 0.7-4 cm, the apex noncucullate, mostly round, rarely acute, the base clasping, without basal lobes; glands absent; ligules inconspicuous, free from blade, light brown to green, nonflbrous, not shredding at apex, deteriorating and deciduous, convolute, 3.5-6.5 cm long. Turions absent. Inflorescences unbranched; peduncles similar, cylindrical, terminal or axillary, erect to rarely recurved, 1-7.3 cm long; spike similar, cylindrical, 0.4-4.8 cm long. Fruits sessile, obovate, turgid, without abaxial or lateral keels, 1.6-3 x l .3-2.2 mm; beak erect, 0.4-0.6 mm long; sides without basal tubercles; embryo with one full spiral. Chromosomes: x = 26.

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Rhizomatous aquatic. Stem branched or simple. Leaves submerged, sessile, lanceolate to orbicular, cordate-amplexicaul, size and shape variable 2-6 cm long, 1.5-2 (-2.5) cm broad, entire or minutely denticulate, rounded to obtuse at the apex, usually alternate below, opposite above, 2-7 (-13)-veined, thin, translucent. Stipules free, small, length variable, less than 1 cm long, soon evanescent. Spike 4-5 cm long, densely flowered. Fruitlets 2-3.5 mm long, 1.5-2 (-3) mm broad, beaked, ventral area convex, irregular or straight, beak more or less keeled.

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Stängel bis 6 m lang, meist verzweigt, rund. Alle Blätter untergetaucht, rundlich bis eiförmig, 3–6(–10) cm lang, fein gezähnt, sitzend und mit tief herzförmigem Grund umfassend. Blütenstand bis 3 cm lang, auf höchstens 10 cm langem Stiel, d

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Çokyıllık, rizomlu sucul bitkiler. Gövde silindirik, dallanmamış ya da üst kısımlarda dallanmış, en çok 200 cm boyunda; filiz üretmez. Yapraklar almaşlı, fırfırlı şeffaf, batık; yaprak kını yaprak tabanından serbest, yaklaşık 14 mm boyunda, açık şekilli, zarsı, dökülücü; yaprak ayası sapsız, 5-25 damarlı, 1,7-6,1 × 1,2-3,4 cm, geniş mızraksı, geniş yumurtamsı, dairesel, yeşil, nadiren yaprak ortaları pas rengi, kenarları düz, bazen belli belirsiz ortalarda dişli; tabanı yüreksi, gövdeyi saran; uçları küt, yuvarlak, sivri bazen çok az külahlı. Çiçekdurumu sapı dik, silindirik, 1,2-5,3 cm uzunluğunda; çiçekdurumu başak, terminal bazen koltuksal, kısa, 1,9-2,7 cm uzunluğunda, kesintisiz. Karpel 4 tane. Meyve tersyumurtamsı, sapsız, 2,5-3,5 × 1,8-2,25 mm; gaga kısa, koyu yeşil ilâ siyah, 0,3-0,5 mm.

6–7. Tiefe, langsam fliessende oder stehende, nährstoffreiche Gewässser, kollin-subalpin. M, J, AN, selten AS.

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Widespread in temperate and subtropical regions of North America, Europe, Asia, and Australia. It is known from two localities in the Neotropics, Guatemala and Cuba. The species occurs in lakes and saline bays, from sea level to 1500 m.

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