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Vascular Plants of California
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Myriophyllum verticillatum
WHORLED 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].
Reference: Ceska et al. 1986 Brittonia 38:73--81
Myriophyllum verticillatum L.
NATIVE
Habit: Monoecious; winter buds club-shaped at ends of non-flowering branches, generally in fall. Stem: > 1 m, dark green to +- black when dry. Leaf: submersed leaves < 5 cm, segments 18--34, < 10 mm, linear, Inflorescence: spike, 5--12 cm, emergent; bracts 3--8(10) mm, pinnately dissected, segments linear.
Ecology: Lakes, marshes; Elevation: < 2072 m. Bioregional Distribution: NCo, n&s SNH, GB; Distribution Outside California: to Alaska, Canada, eastern United States, Eurasia. Flowering Time: Jul--Sep
Unabridged Note: Recognizable by stems that are dark green when fresh and +- black when dry, and by inflorescence bracts that resemble miniature leaves. Club-shaped winter buds develop later in season.
Jepson eFlora Author: Adolf Ceska & Oldriska Ceska
Reference: Ceska et al. 1986 Brittonia 38:73--81
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Botanical illustration including Myriophyllum verticillatum

botanical illustration including Myriophyllum verticillatum

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Citation for this treatment: Adolf Ceska & Oldriska Ceska 2012, Myriophyllum verticillatum, in Jepson Flora Project (eds.) Jepson eFlora, http://ucjeps.berkeley.edu/eflora/eflora_display.php?tid=34279, accessed on June 19, 2019.

Citation for the whole project: Jepson Flora Project (eds.) 2019, Jepson eFlora, http://ucjeps.berkeley.edu/eflora/, accessed on June 19, 2019.

No expert verified images found for Myriophyllum verticillatum.



Geographic subdivisions for Myriophyllum verticillatum:
NCo, n&s SNH, GB
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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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Blue markers indicate specimens that map to one of the expected Jepson geographic subdivisions (see left map). Purple markers indicate specimens collected from a garden, greenhouse, or other non-wild location.
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CCH collections by month

Duplicates counted once; synonyms included.
Species do not include records of infraspecific taxa, if there are more than 1 infraspecific taxon in CA.
Blue line denotes eFlora flowering time.