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''Potamogeton coloratus'', or fen pondweed, is an aquatic plant in the genus ''Potamogeton''. It is found in shallow peaty calcareous lakes, ponds and ditches, commonly associated with lowland fens. ==Description== Fen pondweed grows from perennial, creeping rhizomes. The leaves are broad, thin and translucent with noticeable reticulate veining.〔 Both floating and submerged leaves are produced but the difference between these is often rather indistinct, rather than the marked dimorphism seen in other pondweeds. Often, the leaves of fen pondweed are simply longer and narrower lower down the stem and shorter and rounder towards its apex; the leaves towards the apex of the stem may be floating but often grow just below the surface, giving the plant a distinctive 'drowned' appearance,〔 as though water levels have recently risen. Submerged leaves are 70–175 mm long and 10–30 mm wide.〔 All leaves have the stalk shorter than the blade, and the submerged leaves are almost sessile.〔 The leaves are typically reddish to brownish in colour. Flowers are produced in June to July. Like all pondweeds, they are small and greenish, in spikes up to 45 mm long. The fruits of this species are smaller (1.5-1.9 mm long x 1.0-1.3 mm wide) than Broad-leaved pondweed ''Potamogeton natans'' and Bog Pondweed ''Potamogeton polygonifolius''.〔〔 Turions are not produced.〔 Fen pondweed could be confused with other pondweeds, especially bog pondweed ''P. polygonifolius'', to which it is closely related.〔 However, bog pondweed produces completely opaque floating leaves that are very distinct from the submerged leaves; the submerged leaves are longer and die back relatively early in the season. Bog pondweed also lacks the distinctive net-veined appearance. ''Potamogeton lucens'' has leaves with a similar net-veined appearance, but is more uniform in its growth habit, has denticulate (finely toothed) leaf margins and stipules with two conspicuous keels.〔 ''Potamogeton coloratus'' is diploid, with 2n=28.〔 Hybrids have been described with ''P. berchtoldii'' (''P''. × ''lanceolatus'' Sm.) and ''P. gramineus'' (''P''. × ''billupsii'' Fryer), but both are rare.〔〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Potamogeton coloratus」の詳細全文を読む スポンサード リンク
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