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According to Ceska and Ceska (2010), this species is "Introduced and invasive. North American invasive populations are considered to be of a hybrid origin (M. spicatum x M. sibiricum) by Moody & Les (2002, 2007). Stem drying reddish. No winter buds."
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General: Perennial aquatic from a rhizome, stems usually branched, to 250 cm long, reddish-brown, pinkish-tawny in drying.
Leaves: In whorls of 3 to 5 mostly 1 cm apart or more on stem, those in the middle whorls usually less than 2.5 cm long, simply pinnate with 12 or more segments on each side of rachis; segments rarely to 1.5 cm long, in a regular, feather-like arrangement, about 1-2.5 mm apart; winter buds absent.
Flowers: Spikes to about 15 cm long, emergent erect; flowers usually in whorls of 4 in the axils of bracts; all but the lowest bracts essentially entire and shorter than the flowers and fruits, the lowest comb-like to sharply toothed and commonly exceeding the flowers; flowers progressing from basal whorls of pistillate flowers through 1 perfect flower to the upper whorl of male flowers with reddish, soon deciduous petals about 3 mm long; stamens 8.
Fruits: Mericarps, 4, nearly round, with tiny warts on the dorsal ridges.
Notes: This species was introduced to British Columbia in the early 1970's and has become a serious aquatic weed. In Hitchcock et al. (1961) plants of this species would key out as "Myriophyllum spicatum var. exalbescens."
Recommended citation: Author, Date. Page title. In Klinkenberg, Brian. (Editor) 2020. E-Flora BC:
Electronic Atlas of the Plants of British Columbia [eflora.bc.ca]. Lab for
Advanced Spatial Analysis, Department of Geography, University of British
Columbia, Vancouver. [Accessed:
2023-12-07 1:15:13 PM
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