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Potamogeton americanus, spray showing attachment of cases of caddis fly (fam. Leptoceridae).
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Potamogeton obtusifolius, winter buds. October.
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Potamogeton Robbinsii, photo-micrograph of section through old stem, showing arrangement of mechanical tissue.
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Potamogeton heterophylius. 12, typical habit of land form; 13, terminal portion of rootstock showing tendency to become tuberous; 14, same, more advanced stage; 15, aquarium specimen
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Leafy pondweed (Potamogeton foliosus). Niagra Falls to Michigan and California (After Britton & Brown)
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Potamogeton americanus. 1, seed; 2, seedling 5 days old; 3, seedling 14 days old; 4, seedling of four months; A, winter buds; 5, germinating winter bud, natural size; the last two winter buds belated in development. Aquarium specimen, January 24, 1914
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Potamogeton obtusifolius, erect axes bearing winter buds. October.
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Potamogeton Robbinsii, photo-micrograph of section through old stem, showing arrangement of mechanical tissue--Detail.
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Potamogeton heterophyllus (16-17); Potamogeton perfoliatus (18-19). 16, aquarium specimen; 17, aquarium specimen; 18, winter shoot showing elongation of internodes; 19, growing tips of same
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Potamogeton amplifolius, leaves, showing characteristic mines of Hydrellia.
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Potamogeton americanus. 1, seed; 2, seedling 5 days old; 3, seedling 14 days old; 4, seedling of four months; A, winter buds; 5, germinating winter bud, natural size; the last two winter buds belated in development. Aquarium specimen, January 24, 1914; 6, rootstock with winter bud A, natural size. September
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Potamogeton filiformis (36-37); Potamogeton peclinatus (38-40). 36, habit sketch; 37, detail of tuberous rootstock; 38, young plant developing from tuber; 39, series of tubers; 40, tubers, showing details of early growth
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Potamogeton Robbinsii, branch, showing points where dismemberment occurs.
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Potamogeton heterophyllus.
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Potamogeton amplifolius (7) rootstock; Potamogeton heterophyllus (8); Potamogeton heterophyllus (9-12). 7, rootstock; 8, submerged plant; 9, rootstock not tuberous; 10, tuberous rootstock; 11, tuberous rootstock
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Long-leaved pondweed (Potamogeton lonchites). Found in ponds and slow streams, New Brunswick to Washington, south to Florida and California (After Britton & Brown)
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Curled-leaved Pondweed (Potamogeton crispus). Found in fresh, brackish or even salt water, Massachusetts to Pennsylvania and Virginia. Also in Europe (After Britton & Brown)
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Fennel-leaved pondweed (Potamogeton pectinatus). Found in fresh, brackish, or salt water, Cape Breton to British Columbia, south to Florida, Texas, and California. Also in Europe (After Britton & Brown)
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Potamogeton amplifolius, rooted tip of branch, a propagative structure.
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Potamogeton crispus, germinating burs. October.
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Potamogeton pectinatus, gigantic form of Dudley, portion of leafy spray showing tubers. November.
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Potamogeton crispus (31-32); Potamogeton zosterifolius (33-35). 31, subterranean stem; 32, sprouting bur; 33, winter bud; 34, long section of winter bud; 35, winter bud sprouting
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Potamogeton pectinatus. 45, plant developed in aquarium, suspended in water; 46, sprouting seed; 47, same, later stage; 48, seedling about 10 days old, outer testa of seed removed; 49, seedling three weeks old
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Potamogeton crispus. 20, recumbent branch; 21, spicular bur; 22, denticulate bur; 23, sprouting bur; 24, denticulate bur; 25, spicular bur
