View source for Rhexia

{{Treatment/ID
|accepted_name=Rhexia
|accepted_authority=Gronovius in C. Linnaeus
|publications={{Treatment/Publication
|title=Sp. Pl.
|place=1: 346. 1753
|year=1753
}}
|common_names=Meadow beauty;deergrass
|basionyms=
|synonyms=
|hierarchy=Melastomataceae;Rhexia
|hierarchy_nav=<div class="higher-taxa"><div class="higher-taxon"><small>family</small>[[Melastomataceae]]</div><div class="higher-taxon"><small>genus</small>[[Rhexia]]</div></div>
|etymology=Greek rhexis, rupture, alluding to reputed astringent property to cure wounds
|volume=Volume 10
|mention_page=
|treatment_page=
}}<!--

--><span class="statement" id="st-d0_s0" data-properties="herb growth form"><b>Herbs,</b> sometimes suffrutescent;</span> <span class="statement" id="st-d0_s1" data-properties="caudex height or length or size;caudex texture;caudex size or width">caudices relatively short and woody when present, sometimes becoming spongy-thickened when submerged;</span> <span class="statement" id="st-d0_s2" data-properties="root texture">roots fibrous, root-tubers produced by the roots in some species on the primary-root at base of stem or at irregular positions on secondary-roots.</span> <span class="statement" id="st-d0_s3" data-properties="stem orientation;stem orientation;stem orientation;stem shape;face size;face size;face size;face quantity;face shape;face width;face shape;face width;face morphologies;face pubescence;face pubescence;face pubescence;hair architecture;hair architecture"><b>Stems </b>erect to ascending-erect, ± 4-angled, faces subequal or unequal, if unequal then 1 opposing set convex, broader, the other concave, narrower, the different morphologies alternating at 90° at each node, usually hirsute to villous, hairs bristlelike, often gland-tipped;</span> <span class="statement" id="st-d0_s4" data-properties="bark width;bark relief">bark (if any) thin, exfoliating distally.</span> <span class="statement" id="st-d0_s5" data-properties="leaf architecture;leaf architecture;leaf architecture;leaf architecture;leaf architecture"><b>Leaves </b>petiolate, sessile, or subsessile;</span> <span class="statement" id="st-d0_s6" data-properties="blade architecture;cross-vein fragility;margin architecture or shape;margin shape;margin architecture or shape;margin shape;margin shape;margin shape;margin shape;margin architecture;tooth architecture;surface pubescence;surface pubescence;surface pubescence;surface pubescence;surface pubescence;surface pubescence">blade usually 3-veined (1-veined in R. cubensis), without strong cross-veins, margins entire, subentire, serrate, serrulate, or crenulate, usually with bristle-tipped teeth, rarely gland-tipped, surfaces strigose, villous, hirsute, or glabrous.</span> <span class="statement" id="st-d0_s7" data-properties="inflorescence position or structure subtype;raceme architecture"><b>Inflorescences </b>terminal, cymes or appearing as secund racemes (through abortion of inner branches);</span> <span class="statement" id="st-d0_s8" data-properties="bract duration;bract architecture">bracts often deciduous, subfoliaceous.</span> <span class="statement" id="st-d0_s9" data-properties="flower architecture;flower architecture"><b>Flowers </b>subsessile or short-pedicellate;</span> <span class="statement" id="st-d0_s10" data-properties="hypanthium shape;hypanthium shape;hypanthium shape">hypanthium urceolate to campanulate;</span> <span class="statement" id="st-d0_s11" data-properties="calyx shape;lobe shape">calyx 4-lobed, lobes triangular;</span> <span class="statement" id="st-d0_s12" data-properties="petal duration;petal quantity;petal orientation;petal orientation;petal architecture or shape;petal coloration or odor;petal coloration;petal coloration or density;petal coloration;petal coloration;petal coloration;petal coloration;petal coloration;petal coloration;petal shape;hair size;hair architecture">petals fugacious, 4, ascending or spreading, asymmetric, lavender, lavender-rose, lavender-purple, purple, pink, white, or yellow, short-clawed, midvein extending as a slender, multicellular hair;</span> <span class="statement" id="st-d0_s13" data-properties="stamen quantity;stamen size;whorl quantity;connective base architecture">stamens 8, subequal, in 2 whorls, connective bases appendaged;</span> <span class="statement" id="st-d0_s14" data-properties="anther course;anther orientation;anther shape;anther shape;anther shape;anther architecture or structure in adjective form;anther dehiscence">anthers straight or downcurved, linear to linear-lanceolate, 4-locular (1-locular at anthesis through breakdown of septae), apically to subapically poricidal;</span> <span class="statement" id="st-d0_s15" data-properties="ovary position;ovary fusion;ovary architecture or structure in adjective form">ovary inferior, adnate to floral-tube except apically, 4-locular;</span> <span class="statement" id="st-d0_s16" data-properties="style position;style course;style arrangement or course or shape">style exserted, curved, linear.</span> <span class="statement" id="st-d0_s17" data-properties="fruits capsule dehiscence;fruits capsule dehiscence"><b>Fruits </b>capsules loculicidal, enclosed within hypanthium, dehiscent.</span> <span class="statement" id="st-d0_s18" data-properties=""><b>Seeds </b>cochleate (except cuneate-prismatic in R. alifanus).</span> <span class="statement" id="st-d0_s19" data-properties="seed shape;seed quantity">= 11.</span><!--

-->{{Treatment/Body
|distribution=North America;West Indies (Greater Antilles)
|discussion=<p>Species 13 (13 in the flora).</p><!--
--><p>Hybrids are common between some of the species with elongate anthers (sect. Rhexia) and identifications sometimes are arbitrary. There is no evidence that the other species are involved in hybridization. Tuberous swellings on the roots are produced in some species of sect. Rhexia; presence of these root tubers appears to vary within and among populations.</p><!--
--><p>Rhexia alifanus (sect. Cymborhexia) is the only species of the genus with glabrous, isofacial, subentire, and glaucous leaf blades, caducous bracts, and relatively large, oblong-cuneate, subprismatic seeds (versus small, cochleate seeds in the other species), but it shares with sect. Rhexia (perhaps as a plesiomorphic feature) elongate, curved, small-pored anthers.</p><!--
--><p>Polyploidy occurs in many species of sect. Rhexia. In R. cubensis (2x, 4x, 6x), R. nashii (4x, 6x), and R. virginica (2x, 4x), conspecific plants of different ploidy apparently occur sympatrically and are completely reproductively isolated (no seeds formed in experimental crosses), but there are no obvious morphological differences among them (see chromosome counts, geography, and crossing data in R. Kral and P. E. Bostick 1969). The phylogenetic analysis by G. M. Ionta et al. (2007) indicates that the evolutionary origin of R. cubensis, R. nashii, R. parviflora, and R. salicifolia (sect. Rhexia), as well as R. lutea, probably was through hybridization.</p><!--
--><p>The biological situation is different in Rhexia mariana (in the broad sense, as interpreted by R. Kral and P. E. Bostick 1969). Variety mariana is diploid and is completely reproductively isolated from the two tetraploid varieties (vars. interior and ventricosa); experimental crosses between vars. interior and ventricosa fail to produce viable seeds. Varieties interior and ventricosa are morphologically similar and completely allopatric; each differs from var. mariana in a prominent feature of stem morphology—typical R. mariana has unequal stem faces while each of the two tetraploids has equal faces. These two taxa are treated here at specific rank, apart from R. mariana in the strict sense, following C. W. James (1956).</p><!--
--><p>Based on molecular evidence (G. Clausing and S. S. Renner 2001), Rhexia appears to be sister to Arthrostemma Pavon ex D. Don, a genus of perennial herbs native to Central America and northwestern South America. Arthrostemma ciliatum Pavon ex D. Don has become a damaging invader on the Hawaiian Islands.</p><!--
--><p>The key to Rhexia species below is artificial, a nearly inevitable requirement to separate some of the species.</p>
|tables=
|references=
}}<!--

--><div class="treatment-key">
==Key==
<div class="treatment-key-group">
  
{| class="wikitable fna-keytable"
|-id=key-0-1
|1
|Petals golden-yellow.
|[[Rhexia lutea|Rhexia lutea]]
|-id=key-0-1
|1
|Petals lavender, lavender-rose, lavender-purple, purple, pink, or white.
|[[#key-0-2| > 2]]
|-id=key-0-2
|2
|Inflorescences condensed, mostly obscured by foliaceous bracts; leaf blades ovate to short-elliptic or suborbiculate, 1–2 cm; anthers 1.2–2 mm; roots relatively short, fibrous, lignescent and non-tuberiferous.
|[[#key-0-3| > 3]]
|-id=key-0-3
|3
|Calyx lobes deltate, apices obtuse; hypanthia villous-hirsute, hairs gland-tipped; seeds irregularly ridged.
|[[Rhexia nuttallii|Rhexia nuttallii]]
|-id=key-0-3
|3
|Calyx lobes oblong-lanceolate, apices acute; hypanthia mostly glabrous except along calyx lobes; seeds pebbled or with ridges of domelike processes.
|[[Rhexia petiolata|Rhexia petiolata]]
|-id=key-0-2
|2
|Inflorescences diffuse, not obscured by bracts; leaf blades lanceolate to elliptic, ovate, oblong, oblanceolate, linear, or spatulate, 1.5–7.5 cm; anthers 3–11 mm; roots relatively long, rhizomelike, sometimes tuberiferous, sometimes lignescent (except short and fibrous in R. alifanus).
|[[#key-0-4| > 4]]
|-id=key-0-4
|4
|Stem internodes usually glabrous.
|[[#key-0-5| > 5]]
|-id=key-0-5
|5
|Stem internodes and nodes glabrous; leaf blade margins entire or subentire, teeth remote, low, blunt not bristle-tipped, surfaces glabrous.
|[[Rhexia alifanus|Rhexia alifanus]]
|-id=key-0-5
|5
|Stem internodes glabrous, nodes hirsute to villous; leaf blade margins serrate or crenulate, teeth bristle-tipped, surfaces glabrous, glabrate, strigose, hirsute, or villous.
|[[#key-0-6| > 6]]
|-id=key-0-6
|6
|Anthers 3–3.5 mm.
|[[Rhexia parviflora|Rhexia parviflora]]
|-id=key-0-6
|6
|Anthers 5–8 mm.
|[[#key-0-7| > 7]]
|-id=key-0-7
|7
|Leaf blades 3–9 mm wide, margins shallowly serrate to barely crenulate; hypanthia hispid-hirsute at neck, rim, and calyx lobes, hairs eglandular, yellowish.
|[[Rhexia aristosa|Rhexia aristosa]]
|-id=key-0-7
|7
|Leaf blades (5–)8–20(–35) mm wide, margins serrate or finely serrate; hypanthia glabrous, glabrate, hirsute-villous, or sparsely villous, hairs gland-tipped.
|[[#key-0-8| > 8]]
|-id=key-0-8
|8
|Leaf blades (7–)10–20(–35) mm wide; stem faces subequal, angles narrowly winged.
|[[Rhexia virginica|Rhexia virginica]]
|-id=key-0-8
|8
|Leaf blades (5–)8–15(–20) mm wide; stem faces strongly unequal.
|[[Rhexia mariana|Rhexia mariana]]
|-id=key-0-4
|4
|Stem internodes hirsute to villous or hispid-villous.
|[[#key-0-9| > 9]]
|-id=key-0-9
|9
|Stem faces unequal.
|[[#key-0-10| > 10]]
|-id=key-0-10
|10
|Hypanthia glabrous or glabrate (except calyx rims and lobes); petals 2–2.5 cm.
|[[Rhexia nashii|Rhexia nashii]]
|-id=key-0-10
|10
|Hypanthia usually hirsute-villous or hirsute; petals 1.2–2 cm.
|[[#key-0-11| > 11]]
|-id=key-0-11
|11
|Hypanthia (10–)14–15(–16) mm.
|[[Rhexia cubensis|Rhexia cubensis]]
|-id=key-0-11
|11
|Hypanthia 6–10 mm.
|[[Rhexia mariana|Rhexia mariana]]
|-id=key-0-9
|9
|Stem faces subequal.
|[[#key-0-12| > 12]]
|-id=key-0-12
|12
|Anthers 3–3.5 mm; petals white or pale lavender.
|[[Rhexia parviflora|Rhexia parviflora]]
|-id=key-0-12
|12
|Anthers 5–8 mm; petals pink to lavender-rose, lavender-purple, or purple.
|[[#key-0-13| > 13]]
|-id=key-0-13
|13
|Leaf blades 1–5 mm wide, margins entire or minutely crenulate, ciliate, with gland-tipped hairs; petals 1.1–1.2 cm; hypanthia (4–)5–7(–8) mm.
|[[Rhexia salicifolia|Rhexia salicifolia]]
|-id=key-0-13
|13
|Leaf blades (7–)10–20(–35) mm wide, margins serrate to serrulate, not ciliate; petals 1.2–2 cm; hypanthia 6–10 mm.
|[[#key-0-14| > 14]]
|-id=key-0-14
|14
|Stem angles narrowly winged; stems usually unbranched or few-branched proximally; stem internodes and hypanthia usually sparsely villous, sometimes glabrous.
|[[Rhexia virginica|Rhexia virginica]]
|-id=key-0-14
|14
|Stem angles sharp, without wings or very narrowly winged; stems unbranched or few- to several-branched distally; stem internodes hirsute-villous, hypanthia hirsute-villous, glabrous, or glabrate.
|[[#key-0-15| > 15]]
|-id=key-0-15
|15
|Seed surfaces with papillae in concentric rows; Atlantic coast states.
|[[Rhexia ventricosa|Rhexia ventricosa]]
|-id=key-0-15
|15
|Seed surfaces irregularly ridged in concentric rows or with laterally flattened, domelike processes; c, s United States.
|[[Rhexia interior|Rhexia interior]]
|}
</div></div><!--

-->{{#Taxon:
name=Rhexia
|authority=Gronovius in C. Linnaeus
|rank=genus
|parent rank=family
|synonyms=
|basionyms=
|family=Melastomataceae
|distribution=North America;West Indies (Greater Antilles)
|reference=None
|publication title=Sp. Pl.
|publication year=1753
|special status=
|source xml=
|genus=Rhexia
|anther architecture or structure in adjective form=4-locular
|anther course=straight
|anther dehiscence=poricidal
|anther orientation=downcurved
|anther shape=linear;linear-lanceolate
|bark relief=exfoliating
|bark width=thin
|blade architecture=3-veined
|bract architecture=subfoliaceous
|bract duration=deciduous
|calyx shape=4-lobed
|caudex height or length or size=short
|caudex size or width=spongy-thickened
|caudex texture=woody
|connective base architecture=appendaged
|cross-vein fragility=strong
|face morphologies=alternating
|face pubescence=usually hirsute;villous
|face quantity=1
|face shape=concave;convex
|face size=unequal;unequal;subequal
|face width=narrower;broader
|flower architecture=short-pedicellate;subsessile
|fruits capsule dehiscence=dehiscent;loculicidal
|hair architecture=multicellular;gland-tipped;bristlelike
|hair size=slender
|herb growth form=suffrutescent
|hypanthium shape=urceolate;campanulate
|inflorescence position or structure subtype=terminal
|leaf architecture=subsessile;sessile;subsessile;sessile;petiolate
|lobe shape=triangular
|margin architecture=gland-tipped
|margin architecture or shape=serrate;entire
|margin shape=crenulate;serrulate;crenulate;serrulate;subentire
|ovary architecture or structure in adjective form=4-locular
|ovary fusion=adnate
|ovary position=inferior
|petal architecture or shape=asymmetric
|petal coloration=yellow;white;yellow;white;pink;purple;lavender-rose
|petal coloration or density=lavender-purple
|petal coloration or odor=lavender
|petal duration=fugacious
|petal orientation=spreading;ascending
|petal quantity=4
|petal shape=short-clawed
|raceme architecture=secund
|root texture=fibrous
|seed quantity=11
|seed shape=cochleate
|stamen quantity=8
|stamen size=subequal
|stem orientation=erect;ascending-erect
|stem shape=4-angled
|style arrangement or course or shape=linear
|style course=curved
|style position=exserted
|surface pubescence=glabrous;hirsute;glabrous;hirsute;villous;strigose
|tooth architecture=bristle-tipped
|whorl quantity=2
}}<!--

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