View source for Lythrum

{{Treatment/ID
|accepted_name=Lythrum
|accepted_authority=Linnaeus
|publications={{Treatment/Publication
|title=Sp. Pl.
|place=1: 446. 1753
|year=1753
}}
|common_names=Loosestrife
|basionyms=
|synonyms=
|hierarchy=Lythraceae;Lythrum
|hierarchy_nav=<div class="higher-taxa"><div class="higher-taxon"><small>family</small>[[Lythraceae]]</div><div class="higher-taxon"><small>genus</small>[[Lythrum]]</div></div>
|etymology=Greek lythron, gore, alluding to use of L. salicaria in arresting hemorrhages
|volume=Volume 10
|mention_page=
|treatment_page=
}}<!--

--><span class="statement" id="st-d0_s0" data-properties="herb duration;herb duration;herb habitat;herb habitat;herb atypical some measurement;herb some measurement;herb coloration;herb coloration;herb coloration;herb coloration;herb coloration;herb coloration;herb coloration;herb pubescence;herb pubescence"><b>Herbs,</b> annual or perennial,or subshrubs, terrestrial or amphibious, 0.5–15 (–30) dm, green, gray-green, or gray-white glaucous, usually glabrous, sometimes puberulent.</span> <span class="statement" id="st-d0_s1" data-properties="stem orientation;stem orientation;stem growth form;stem architecture;growth life cycle;growth shape;growth architecture;stem location;stem size or width;tissue texture"><b>Stems </b>erect, weakly erect, or procumbent, usually branched, youngest growth narrowly 4-ridged or winged, submerged stems sometimes thickened by spongy tissue.</span> <span class="statement" id="st-d0_s2" data-properties=""><b>Leaves </b>opposite, subopposite, alternate, subalternate, or whorled;</span> <span class="statement" id="st-d0_s3" data-properties="leaf arrangement;leaf arrangement;leaf arrangement;leaf arrangement;leaf arrangement;leaf arrangement;leaf arrangement;leaf architecture;leaf architecture">sessile or subsessile;</span> <span class="statement" id="st-d0_s4" data-properties="blade shape;blade shape;blade shape;blade shape;blade shape;blade shape;blade shape;blade shape;blade shape;blade shape;blade shape;blade shape;blade shape;base shape;base shape;base shape;base shape;base shape">blade ovate, obovate, oblong, oblong-lanceolate, lanceolate, oblanceolate, linear, linear-oblong, linear-lanceolate, orbiculate, or suborbiculate, base rounded, cordate, or attenuate.</span> <span class="statement" id="st-d0_s5" data-properties="inflorescence shape"><b>Inflorescences </b>terminal and spikelike or racemes.</span> <span class="statement" id="st-d0_s6" data-properties="flower architecture;flower architecture;flower architecture;flower architecture;flower architecture;flower architecture"><b>Flowers </b>sessile, subsessile, or short-pedicellate, actinomorphic, mono, di, or tristylous;</span> <span class="statement" id="st-d0_s7" data-properties="floral-tube position;floral-tube shape;floral-tube shape;floral-tube architecture or shape">floral-tube perigynous, usually cylindrical or obconic (campanulate in L. portula), 8–12-ribbed;</span> <span class="statement" id="st-d0_s8" data-properties="epicalyx segment height or length or size;epicalyx segment length or size">epicalyx segments shorter to or up to 2 times longer than sepals;</span> <span class="statement" id="st-d0_s9" data-properties="sepal quantity;sepal shape;sepal shape;sepal shape;sepal shape;sepal size or width">sepals 6, narrowly deltate to subulate, obtuse and thickened in L. tribracteatum;</span> <span class="statement" id="st-d0_s10" data-properties="petal duration;petal quantity;petal coloration;petal coloration;petal coloration;petal coloration;petal coloration;petal coloration;petal coloration;petal coloration;midvein coloration;midvein coloration">petals caducous, (0 or) 6, purple, lavender, rose, rose-purple, pink, or white, sometimes with purple or red midvein;</span> <span class="statement" id="st-d0_s11" data-properties="ovary nectary presence">nectary encircling base of ovary or absent;</span> <span class="statement" id="st-d0_s12" data-properties="stamen atypical quantity;stamen atypical quantity;stamen quantity;stamen quantity;stamen quantity;complementing quantity;style quantity">stamens (2–) 4–6 (–12), usually 6 or 12, in 1 or 2 whorls, complementing style lengths;</span> <span class="statement" id="st-d0_s13" data-properties="ovary architecture or structure in adjective form">ovary 2-locular;</span> <span class="statement" id="st-d0_s14" data-properties="placenta shape">placenta elongate;</span> <span class="statement" id="st-d0_s15" data-properties="style size;style position;style position">style slender, included or well exserted;</span> <span class="statement" id="st-d0_s16" data-properties="stigma architecture or shape">stigma capitate.</span> <span class="statement" id="st-d0_s17" data-properties="wall width;wall condition or texture;wall dehiscence;wall dehiscence;wall dehiscence;wall dehiscence"><b>Fruits </b>capsules, walls thin and dry, usually dehiscent, dehiscence septicidal or septifragal (indehiscent and splitting irregularly in L. portula, placenta and seeds remaining within capsules).</span> <span class="statement" id="st-d0_s18" data-properties="seed average count;seed quantity;seed shape;seed shape;seed shape;seed shape;seed some measurement"><b>Seeds </b>10–90 (+), obovoid to fusiform or subglobose, to 1 mm;</span> <span class="statement" id="st-d0_s19" data-properties="cotyledon shape">cotyledons ± complanate.</span><!--

-->{{Treatment/Body
|distribution=North America;Mexico;South America;Europe;Asia;Africa;Australia;in West Indies
|discussion=<p>Species ca. 35 (12 in the flora).</p><!--
--><p>Lythrum is represented in North America by equal numbers of native and introduced species. Lythrum thymifolia Linnaeus, native to the Mediterranean, was reported from Mobile, Alabama, on ballast in 1893 (C. T. Mohr 1901). It is similar to L. hyssopifolia but consistently has stamens reduced to two or three, leaves usually less than 2 mm wide, and is monostylous.</p><!--
--><p>Lythrum is one of six genera in Lythraceae with a heterostylous breeding system and one of three in the family with tristylous species (also Decodon and the incipiently tristylous tropical genus Adenaria Kunth). Lythrum includes mono-, di-, and tristylous species. All native North American Lythrum species are distylous. Among the introduced species, L. junceum, L. salicaria, and L. virgatum are tristylous and L. hyssopifolia, L. portula, and L. tribracteatum are monostylous. The native North American species represent a single lineage corresponding taxonomically to subsect. Pythagorea Koehne. Some species of the subsection are taxonomically difficult and have shown little molecular divergence (J. A. Morris 2007). Hybridization and introgression are suspected where two native species co-occur, and also possibly between non-native species or native with non-native (B. Ertter and D. Gowen 2019).</p>
|tables=
|references=
}}<!--

--><div class="treatment-key">
==Key==
<div class="treatment-key-group">
  
{| class="wikitable fna-keytable"
|-id=key-0-1
|1
|Floral tubes broadly campanulate, 1 × 1.5 mm, widths greater than lengths; capsules indehiscent, splitting irregularly; stems mostly decumbent to creeping.
|[[Lythrum portula|Lythrum portula]]
|-id=key-0-1
|1
|Floral tubes cylindrical or obconic, 3–7 × (0.4–)1–3 mm, lengths distinctly greater than widths; capsules septicidal or septifragal; stems erect, decumbent, or prostrate.
|[[#key-0-2| > 2]]
|-id=key-0-2
|2
|Inflorescences spikelike, terminal (in L. virgatum racemose proximally, spikelike distally); flowers tristylous; stamens 12.
|[[#key-0-3| > 3]]
|-id=key-0-3
|3
|Leaf blades lanceolate, bases cordate or rounded; plants usually gray-puberulent, sometimes glabrate.
|[[Lythrum salicaria|Lythrum salicaria]]
|-id=key-0-3
|3
|Leaf blades lanceolate to narrowly linear, bases attenuate; plants glabrous.
|[[Lythrum virgatum|Lythrum virgatum]]
|-id=key-0-2
|2
|Inflorescences racemose, diffuse, leafy; flowers mono-, di-, or tristylous; stamens (2–)4–12.
|[[#key-0-4| > 4]]
|-id=key-0-4
|4
|Herbs or subshrubs 0.5–6 dm; stems decumbent or procumbent to erect, unbranched, branched from near base, or sparsely branched (much-branched distally in L. ovalifolium), sometimes with short accessory branches distally.
|[[#key-0-5| > 5]]
|-id=key-0-5
|5
|Floral tubes obconic, with red spots on proximal half; epicalyx segments about equal to and more prominent than sepals; flowers tristylous; stamens 12.
|[[Lythrum junceum|Lythrum junceum]]
|-id=key-0-5
|5
|Floral tubes obconic or cylindric, without red spots; epicalyx segments shorter than, equal to, or longer than sepals; flowers mono- or distylous; stamens (2–)4–6(–12).
|[[#key-0-6| > 6]]
|-id=key-0-6
|6
|Floral tubes obcconic, lengths 8–10 times width at tube base; epicalyx segments as long as or longer than sepals; flowers monostylous.
|[[Lythrum tribracteatum|Lythrum tribracteatum]]
|-id=key-0-6
|6
|Floral tubes cylindric or slightly obconic, lengths 5 times or less widths; epicalyx segments about 2 times longer than sepals; flowers mono- or distylous.
|[[#key-0-7| > 7]]
|-id=key-0-7
|7
|Leaves opposite throughout, equal to or shorter than internodes; flowers distylous.
|[[Lythrum flagellare|Lythrum flagellare]]
|-id=key-0-7
|7
|Leaves mostly alternate, sometimes opposite proximally, mostly longer than internodes and closely overlapping distally; flowers mono- or distylous.
|[[#key-0-8| > 8]]
|-id=key-0-8
|8
|Plants gray-green glaucous; leaf blade bases rounded; petals pink or rose, 1/2 length of floral tube; flowers mono- stylous.
|[[Lythrum hyssopifolia|Lythrum hyssopifolia]]
|-id=key-0-8
|8
|Plants green to slightly gray glaucous; leaf blade bases attenuate; petals pale purple to purple, sometimes with red midvein, about as long as floral tube; flowers distylous.
|[[Lythrum ovalifolium|Lythrum ovalifolium]]
|-id=key-0-4
|4
|Herbs or subshrubs (3–)5–15 dm; stems erect, much-branched distally; flowers distylous.
|[[#key-0-9| > 9]]
|-id=key-0-9
|9
|Leaves usually opposite or subopposite throughout, rarely alternate; floral nectaries absent.
|[[Lythrum lineare|Lythrum lineare]]
|-id=key-0-9
|9
|Leaves usually opposite to subopposite proximally, alternate distally or sometimes throughout; floral nectaries encircling bases of ovaries.
|[[#key-0-10| > 10]]
|-id=key-0-10
|10
|Branch leaves abruptly and conspicuously smaller than those on main stems; floral tube obconic; pedicels slender; epicalyx segments and sepals about equal length.
|[[Lythrum curtissii|Lythrum curtissii]]
|-id=key-0-10
|10
|Branch leaves gradually smaller than those on main stems; floral tube cylindrical; pedicels stout; epicalyx segments equal to or to 2 times length of sepals.
|[[#key-0-11| > 11]]
|-id=key-0-11
|11
|Herbs or subshrubs green or slightly gray glaucous; leaf blades ovate to oblong and bases subcordate to rounded, or lanceolate to linear- lanceolate and bases attenuate.
|[[Lythrum alatum|Lythrum alatum]]
|-id=key-0-11
|11
|Herbs whitish gray glaucous; leaf blades oblong-lanceolate proximally, mostly linear or linear-oblong distally, bases rounded.
|[[Lythrum californicum|Lythrum californicum]]
|}
</div></div><!--

-->{{#Taxon:
name=Lythrum
|author=Shirley A. Graham
|authority=Linnaeus
|rank=genus
|parent rank=family
|synonyms=
|basionyms=
|family=Lythraceae
|distribution=North America;Mexico;South America;Europe;Asia;Africa;Australia;in West Indies
|reference=None
|publication title=Sp. Pl.
|publication year=1753
|special status=
|source xml=
|genus=Lythrum
|base shape=attenuate;cordate;attenuate;cordate;rounded
|blade shape=suborbiculate;orbiculate;suborbiculate;orbiculate;linear-lanceolate;linear-oblong;linear;oblanceolate;lanceolate;oblong-lanceolate;oblong;obovate;ovate
|complementing quantity=1
|cotyledon shape=complanate
|epicalyx segment height or length or size=shorter
|epicalyx segment length or size=0-2 times longer than sepals
|floral-tube architecture or shape=8-12-ribbed
|floral-tube position=perigynous
|floral-tube shape=obconic;cylindrical
|flower architecture=actinomorphic;short-pedicellate;subsessile;short-pedicellate;subsessile;sessile
|growth architecture=winged
|growth life cycle=youngest
|growth shape=4-ridged
|herb atypical some measurement=15dm;30dm
|herb coloration=glaucous;gray-white;gray-green;glaucous;gray-white;gray-green;green
|herb duration=perennial;annual
|herb habitat=amphibious;terrestrial
|herb pubescence=puberulent;glabrous
|herb some measurement=0.5dm;15dm
|inflorescence shape=spikelike
|leaf architecture=subsessile;sessile
|leaf arrangement=whorled;subalternate;whorled;subalternate;alternate;subopposite;opposite
|midvein coloration=red;purple
|ovary architecture or structure in adjective form=2-locular
|ovary nectary presence=absent
|petal coloration=white;pink;white;pink;rose-purple;rose;lavender;purple
|petal duration=caducous
|petal quantity=6
|placenta shape=elongate
|seed average count=90;90
|seed quantity=10;90
|seed shape=obovoid;fusiform or subglobose
|seed some measurement=0mm;1mm
|sepal quantity=6
|sepal shape=obtuse;narrowly deltate;subulate
|sepal size or width=thickened
|stamen atypical quantity=6;12
|stamen quantity=12;6;4;6
|stem architecture=branched
|stem growth form=procumbent
|stem location=submerged
|stem orientation=erect;erect
|stem size or width=thickened
|stigma architecture or shape=capitate
|style position=exserted;included
|style quantity=1
|style size=slender
|tissue texture=spongy
|wall condition or texture=dry
|wall dehiscence=septifragal;septicidal;dehiscence;dehiscent
|wall width=thin
}}<!--

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