View source for Myriophyllum alterniflorum

{{Treatment/ID
|accepted_name=Myriophyllum alterniflorum
|accepted_authority=de Candolle in J. Lamarck and A. P. de Candolle
|publications={{Treatment/Publication
|title=Fl. Franç., ed.
|place=3, 6: 529. 1815
|year=1815
}}
|common_names=Alternate-flowered water-milfoil;myriophylle à fleurs alternes
|basionyms=
|synonyms={{Treatment/ID/Synonym
|name=Myriophyllum alterniflorum var. americanum
|authority=Pugsley
|rank=variety
}}
|hierarchy=Haloragaceae;Myriophyllum;Myriophyllum alterniflorum
|hierarchy_nav=<div class="higher-taxa"><div class="higher-taxon"><small>family</small>[[Haloragaceae]]</div><div class="higher-taxon"><small>genus</small>[[Myriophyllum]]</div><div class="higher-taxon"><small>species</small>[[Myriophyllum alterniflorum]]</div></div>
|volume=Volume 10
|mention_page=
|treatment_page=
}}<!--

--><span class="statement" id="st-d0_s0" data-properties="herb reproduction;herb growth form or habitat;stand density"><b>Herbs </b>monoecious, aquatic, often forming dense stands.</span> <span class="statement" id="st-d0_s1" data-properties="stem architecture;stem some measurement"><b>Stems </b>often branched, to 2.5 m.</span> <span class="statement" id="st-d0_s2" data-properties="turion presence"><b>Turions </b>absent.</span> <span class="statement" id="st-d0_s3" data-properties="distal leaf quantity;distal leaf arrangement;leaf location;leaf arrangement;leaf architecture"><b>Leaves </b>usually in whorls of 3 or 4 (or 5), rarely opposite, distal emersed leaves alternate, heteromorphic;</span> <span class="statement" id="st-d0_s4" data-properties="petiole some measurement">petiole 0–0.5 mm;</span> <span class="statement" id="st-d0_s5" data-properties="leaf location;leaf shape;leaf shape;leaf shape;leaf shape;leaf shape;leaf atypical length;leaf length;outline atypical width;outline atypical width;outline width;segment atypical quantity;segment quantity;segment shape;longest segment atypical some measurement;longest segment some measurement">submersed leaves pectinate, ovate to elliptic or obovate in outline, 3–16 (–40) × (3–) 4–10 (–14) mm, segments 6–16 (–20), linear-filiform, longest segment 2–11 (–15) mm;</span> <span class="statement" id="st-d0_s6" data-properties="leaf location;leaf arrangement or shape;leaf shape;leaf shape;leaf shape;leaf shape;leaf length;leaf width;segment atypical quantity;segment quantity;margin shape;margin shape;margin shape">emersed leaves elliptic to oblanceolate or spatulate proximally, pectinate to pinnatifid distally, 0.7–2 × 0.3–0.5 mm, segments 0–10 (–12), margins ± serrate to shallowly lobed.</span> <span class="statement" id="st-d0_s7" data-properties="inflorescence some measurement"><b>Inflorescences </b>to 12 cm;</span> <span class="statement" id="st-d0_s8" data-properties="flower architecture;flower architecture;bract arrangement">flowers proximally pistillate, in whorls of 4, often medially bisexual, distally staminate from alternate bracts;</span> <span class="statement" id="st-d0_s9" data-properties="bracteole coloration;bracteole coloration;bracteole coloration;bracteole shape;bracteole shape;bracteole shape;bracteole length;bracteole width;margin coloration;margin coloration;margin coloration;margin coloration;margin shape;margin shape;margin shape;apex shape">bracteoles cream to stramineous, with distinct brown to purple margins, ovate to depressed-ovate, 0.2–0.5 × 0.2–0.5 mm, margins serrate to irregularly fringed, apex often aristate.</span> <span class="statement" id="st-d0_s10" data-properties="flower architecture;sepal coloration;sepal coloration;sepal coloration;sepal shape;sepal length;sepal width"><b>Staminate </b>flowers: sepals cream to stramineous, narrowly triangular, 0.1–0.2 × 0.1 mm;</span> <span class="statement" id="st-d0_s11" data-properties="flower architecture;petal duration;petal coloration;petal shape;petal shape;petal shape;petal atypical length;petal length;petal atypical width;petal width">petals caducous, cream, elliptic to obovate, (0.7–) 1.3–1.8 × (0.4–) 0.6–1 mm;</span> <span class="statement" id="st-d0_s12" data-properties="flower architecture;stamen quantity;filament some measurement;anther coloration;anther coloration;anther coloration;anther length;anther width">stamens 8, filaments to 0.6 mm, anthers cream to purple, 1.1–1.5 ×0.2–0.4 mm.</span> <span class="statement" id="st-d0_s13" data-properties="flower architecture;sepal coloration;sepal shape;sepal shape;sepal shape;sepal shape;sepal length;sepal width"><b>Pistillate </b>flowers: sepals cream, lanceolate to triangular or deltate, 0.1–0.2 × 0.1 mm;</span> <span class="statement" id="st-d0_s14" data-properties="flower architecture;petal duration;petal duration;petal coloration;petal shape;petal length;petal width">petals usually caducous, rarely persistent, cream, widely ovate, 0.2–0.4 × 0.2–0.3 mm;</span> <span class="statement" id="st-d0_s15" data-properties="flower architecture;pistil some measurement;stigma coloration;stigma coloration;stigma coloration;stigma shape;stigma some measurement">pistils 0.7–1.1 mm, stigmas red to ± purple, pulvinate, to 0.3 mm.</span> <span class="statement" id="st-d0_s16" data-properties="fruit shape;fruit shape"><b>Fruits </b>ovoid, 4-lobed.</span> <span class="statement" id="st-d0_s17" data-properties="mericarp coloration;mericarp coloration;mericarp coloration;mericarp shape;mericarp shape;mericarp shape;mericarp length;mericarp width;mericarp shape;abaxial surface shape;abaxial surface relief;trichome coloration;trichome coloration;trichome coloration;trichome coloration or relief"><b>Mericarps </b>olive-green to redbrown, cylindric to narrowly ovoid, 1.3–1.6 × 0.3–0.4 mm, transversely widely obovate, abaxial surface broadly rounded, irregularly to densely papillate, sometimes with orange to red, punctate trichomes, wings and ridges absent.</span> <span class="statement" id="st-d0_s18" data-properties="wing presence;ridge presence;2n chromosome quantity">2n = 14.</span><!--

-->{{Treatment/Body
|phenology=Flowering and fruiting Apr–Sep.
|habitat=Oligotrophic to mesotrophic waters, lakes, rivers, sandy substrates.
|elevation=0–500 m.
|distribution=Greenland;St. Pierre and Miquelon;Man.;N.B.;Nfld. and Labr. (Nfld.);N.W.T.;N.S.;Ont.;Que.;Sask.;Alaska;Conn.;Maine;Mass.;Mich.;Minn.;N.H.;N.Y.;R.I.;Vt.;Wis.;Eurasia;n Africa
|discussion=<p>Myriophyllum alterniflorum is distinguished in flower and fruit by minute, alternate, entire distal floral bracts, a characteristic shared only with M. laxum. Unlike the flowers of other Myriophyllum species in the flora, those of M. alterniflorum are widely scattered along the inflorescence and the tip of the spike is often nutant. The pistils are relatively small, each having a prominent, purple, pulvinate stigma that is as broad as or broader than the ovary and persistent in fruit. The pistil and mericarp surface has scattered orange to red punctate trichomes not seen on the pistils or mericarps of any other water-milfoil in the flora area. The cream, depressed-ovate, fringed, often aristate bracteoles with brown to red margins are also distinctive. Seed-set appears to be rare in M. alterniflorum. Specimens examined from Greenland far exceed other North American plants in the size of their leaves and staminate flowers. North American plants with relatively short leaves and a bushy habit have been referred to as var. americanum. Plants of this form can be confused with the relatively small M. sibiricum and M. verticillatum in northern latitudes but are distinguishable based on floral characters. Leaf size in M. alterniflorum is plastic and continuous in variation, thus varieties are not recognized here as separate taxa.</p>
|tables=
|references=
}}<!--

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-->{{#Taxon:
name=Myriophyllum alterniflorum
|authority=de Candolle in J. Lamarck and A. P. de Candolle
|rank=species
|parent rank=genus
|synonyms=Myriophyllum alterniflorum var. americanum
|basionyms=
|family=Haloragaceae
|phenology=Flowering and fruiting Apr–Sep.
|habitat=Oligotrophic to mesotrophic waters, lakes, rivers, sandy substrates.
|elevation=0–500 m.
|distribution=Greenland;St. Pierre and Miquelon;Man.;N.B.;Nfld. and Labr. (Nfld.);N.W.T.;N.S.;Ont.;Que.;Sask.;Alaska;Conn.;Maine;Mass.;Mich.;Minn.;N.H.;N.Y.;R.I.;Vt.;Wis.;Eurasia;n Africa
|reference=None
|publication title=Fl. Franç., ed.
|publication year=1815
|special status=
|source xml=
|genus=Myriophyllum
|species=Myriophyllum alterniflorum
|2n chromosome quantity=14
|abaxial surface relief=papillate
|abaxial surface shape=rounded
|anther coloration=cream;purple
|anther length=1.1mm;1.5mm
|anther width=0.2mm;0.4mm
|apex shape=aristate
|bract arrangement=alternate
|bracteole coloration=cream;stramineous
|bracteole length=0.2mm;0.5mm
|bracteole shape=ovate;depressed-ovate
|bracteole width=0.2mm;0.5mm
|distal leaf arrangement=opposite
|distal leaf quantity=3
|filament some measurement=0mm;0.6mm
|flower architecture=pistillate;pistillate;pistillate;staminate;staminate;staminate;staminate;pistillate
|fruit shape=4-lobed;ovoid
|herb growth form or habitat=aquatic
|herb reproduction=monoecious
|inflorescence some measurement=0cm;12cm
|leaf architecture=heteromorphic
|leaf arrangement=alternate
|leaf arrangement or shape=elliptic
|leaf atypical length=16mm;40mm
|leaf length=0.7mm;2mm
|leaf location=emersed;submersed;emersed
|leaf shape=pectinate;pinnatifid
|leaf width=0.3mm;0.5mm
|longest segment atypical some measurement=11mm;15mm
|longest segment some measurement=2mm;11mm
|margin coloration=brown;purple
|margin shape=serrate;irregularly fringed
|mericarp coloration=olive-green;redbrown
|mericarp length=1.3mm;1.6mm
|mericarp shape=obovate;cylindric;narrowly ovoid
|mericarp width=0.3mm;0.4mm
|outline atypical width=10mm;14mm
|outline width=4mm;10mm
|petal atypical length=0.7mm;1.3mm
|petal atypical width=0.4mm;0.6mm
|petal coloration=cream;cream
|petal duration=persistent;caducous;caducous
|petal length=0.2mm;0.4mm
|petal shape=ovate;elliptic;obovate
|petal width=0.2mm;0.3mm
|petiole some measurement=0mm;0.5mm
|pistil some measurement=0.7mm;1.1mm
|ridge presence=absent
|segment atypical quantity=10;12
|segment quantity=0;10
|segment shape=linear-filiform
|sepal coloration=cream;cream;stramineous
|sepal length=0.1mm;0.2mm
|sepal shape=lanceolate;triangular or deltate
|sepal width=0.1;0.1
|stamen quantity=8
|stand density=dense
|stem architecture=branched
|stem some measurement=0m;2.5m
|stigma coloration=red;more or less purple
|stigma shape=pulvinate
|stigma some measurement=0mm;0.3mm
|trichome coloration=orange;red
|trichome coloration or relief=punctate
|turion presence=absent
|wing presence=absent
}}<!--

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