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Myriophyllum spicatum
EURASIAN WATER-MILFOIL

Higher Taxonomy
Family: HaloragaceaeView Description 

Common Name: WATER-MILFOIL FAMILY
Habit: [Annual, shrub] perennial herb, generally aquatic or semiterrestrial, dioecious or monoecious. Leaf: cauline, opposite, alternate or whorled; submersed blades pinnately divided, segments thread-like; emergent leaves simple, entire to divided. Inflorescence: raceme, spike, or panicle; flowers 1 or clustered, short-pedicelled to +- sessile. Flower: generally unisexual, small; calyx tube short, fused to ovary, lobes 2--4; petals generally 2--4; stamens 4 or 8, filaments generally short; ovary inferior, chambers 1--4, styles 2--4, separate, stigmas generally plumose. Fruit: fleshy or of nut-like mericarps, dehiscent or not. Seed: generally 1 per chamber.
Genera In Family: 6--8 genera, +- 100 species: especially southern hemisphere, some cultivated. Note: Haloragis erecta (Murray) Eichler not naturalized in California.
eFlora Treatment Author: Adolf Ceska & Oldriska Ceska
Scientific Editor: Bruce G. Baldwin.
Genus: MyriophyllumView DescriptionDichotomous Key

Common Name: WATER-MILFOIL
Habit: Plant from rhizomes, occasionally with overwintering buds (late in growing season); occasionally terrestrial. Stem: simple or branched, generally green. Leaf: submersed leaves generally whorled, 3--6 per node; emergent leaves entire to pinnately divided, occasionally bract-like. Inflorescence: generally emergent, spike-like, simple or branched, terminal, flowers in whorls. Flower: proximal pistillate, middle occasionally bisexual, distal staminate; calyx lobes 4; petals generally 4, ephemeral on staminate flowers, minute or 0 on pistillate flowers; stamens generally 8; ovary 4-chambered. Fruit: mericarps 4, nut-like.
Species In Genus: +- 60 species: worldwide. Etymology: (Greek: many leaves, from leaf segments) Note: Myriophyllum specimens best collected in flower or fruit.
Unabridged Note: Plants should be washed first and then "floated" on the herbarium mounting paper in a shallow dish with water [see Ceska & Ceska 1987 Ann Missouri Bot Gard 73:825--827].

Myriophyllum spicatum L.
NATURALIZED
Habit: Monoecious; winter buds 0. Stem: > 1 m, +- red to light green when dry. Leaf: submersed leaves < 3 cm, segments >= 28, < 10 mm, linear, angles, spacing uniform throughout leaf. Inflorescence: spike, 4--8 cm, emergent; bracts 1--3 mm, < flowers, lanceolate, entire to toothed.
Ecology: Uncommon. Ditches, lake margins; Elevation: < 2080 m. Bioregional Distribution: NCoRI, SNF, n SNH, GV, SnFrB, SCo, SnBr, PR, MP; Distribution Outside California: to British Columbia, eastern Canada, eastern United States; native to Eurasia, northern Africa. Flowering Time: Jul--Sep
Unabridged Note: Recognizable by large number of parallel leaf segments that stand in acute angles to rachis.
eFlora Treatment Author: Adolf Ceska & Oldriska Ceska
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Citation for this treatment: Adolf Ceska & Oldriska Ceska 2016. Myriophyllum spicatum, in Jepson Flora Project (eds.) Jepson eFlora, http://ucjeps.berkeley.edu/cgi-bin/get_IJM.pl?tid=34276, accessed on May 04, 2016.

Citation for the whole project: Jepson Flora Project (eds.) 2016. Jepson eFlora, http://ucjeps.berkeley.edu/IJM.html, accessed on May 04, 2016.


Myriophyllum spicatum
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© 2009 Barry Rice

More photos of Myriophyllum spicatum in CalPhotos


Geographic subdivisions for Myriophyllum spicatum:
NCoRI, SNF, n SNH, GV, SnFrB, SCo, SnBr, PR, MP;
Markers link to CCH specimen records. If the markers are obscured, reload the page [or change window size and reload]. Yellow markers indicate records that may provide evidence for eFlora range revision or may have georeferencing or identification issues.
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map of distribution 1
(Note: any qualifiers in the taxon distribution description, such as 'northern', 'southern', 'adjacent' etc., are not reflected in the map above, and in some cases indication of a taxon in a subdivision is based on a single collection or author-verified occurence).

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Duplicates counted once; synonyms included.
Species do not include records of infraspecific taxa.
Blue line denotes eFlora flowering time.