1. Lythraceae J.St.-Hil.

    1. This family is accepted.

[FTEA]

Lythraceae, B. Verdcourt. Flora of Tropical East Africa. 1984

Habit
Annual or perennial herbs, subshrubs, shrubs or trees
Leaves
Leaves simple, opposite or verticillate, rarely alternate; stipules absent or minute
Flowers
Flowers regular or slightly irregular, hermaphrodite, (3–)4, 6, 8(–16)-merous, solitary to paniculate, sometimes di- or tri-morphic
Calyx
Sepals united into a tube (hypanthium), lobes valvate, often with small appendages between
Corolla
Petals free, inserted towards the top of the calyx-tube, alternating with the sepals, folded in bud, or absent
Androecium
Stamens usually 4 or 8, less often many (10–200) or fewer (1–2), inserted below the petals; filaments sometimes of different lengths in the different forms of flower, usually inflexed in bud; anthers 2-thecous, opening lengthwise
Gynoecium
Ovary superior (except Punica), sessile or shortly stipitate, completely or incompletely 2–6-locular, rarely unilocular or multilocular (>i>Punica); style simple, sometimes of different lengths in different forms of flower; stigma often ± capitate; ovules 2–numerous on axile placentas sometimes not reaching apex of ovary (parietal in one >i>Ammannia)
Fruits
Fruit capsular or baccate, opening by a transverse slit or valves or bursting irregularly or ± indehiscent
Seeds
Seeds numerous, without endosperm
[FZ]

Lythraceae, A. Fernandes. Flora Zambesiaca 4. 1978

Habit
Annual or perennial (sometimes marshy or aquatic) herbs, suffrutices, shrublets, shrubs or trees
Leaves
Leaves simple, entire, 1-nerved or ± distinctly penninerved, decussate, sometimes verticillate, rarely alternate; stipules 0 or 2–10 or more, small, subulate, axillary
Flowers
Flowers bisexual, actinomorphic or very rarely zygo-morphic, (3)4–5(6–16)-merous, homomorphic or often di-trimorphic
Inflorescences
Inflorescence various from single axillary flowers to fasciculate, cymose or paniculate; pedicels usually bracteolate
Calyx
Calyx persistent, tubular, urceolate or campanulate, the lobes alternating often with ± developed appendages in the sinuses
Corolla
Petals inserted in the calyx-tube, as many as and alternating with the calyx-lobes, sometimes few or 0, often clawed, membranous, corrugated and imbricate in the bud, equal or sometimes unequal
Androecium
Stamens numerous (32–200) in the primitive woody genera, often as many as the calyx-lobes, sometimes fewer (2 or 1) in the more advanced herbaceous ones, equal or sometimes very unequal (in heterostylous plants), inserted on the calyx-tube; filaments free; anthers 2-locular, bent inwards in the bud, dorsifixed and versatile, rarely basifixed (Pleurophora and Crimea, not from FZ area), dehiscing by longitudinal slits
Nectaries
Disk absent or very small, cupular or unilateral
Gynoecium
Ovary usually free, sessile or stipitate, 2–6-locular or 1-locular (Cryptotheca); placentation axile, rarely basal, sometimes the central axis not reaching to the top of the ovary; style absent, short or elongate and flexuous; stigma capitate or punctiform, rarely 2-lobed; ovules numerous to 2, small, anatropous, ascending
Fruits
Fruit mostly a capsule included in the calyx-tube or ± exserted, indehiscent or opening loculicidally or septicidally by valves or by a transverse lid or irregularly, with the placentas forming a central column
Seeds
Seeds 2-numerous, various in form, small, sometimes winged; embryo straight, with endosperm; cotyledons flat or rarely convolute
[NTK]

Graham, S. & Cavalcanti, T.B. (2009). Neotropical Lythraceae.

Morphology
Description

Trees, shrubs or herbs, younger stems often quadrangulate.  Leaves opposite, less often whorled or subalternate, simple , entire , estipulate, colleters present in leaf axils; blades membranous or coriaceous , venation brochidodromous Inflorescences indeterminate, racemes, cymes, or clusters, rarely flowers solitary; pedicels with prophylls (bracteoles).  Flowers actinomorphic or zygomorphic , perfect, perigynous , (4)- 4-6 -(16)- merous ; floral tube campanulate to tubular, often conspicuously veined, persistent except in Lafoensia; sepals valvate , petals (0)-4-6(-many), inserted on the inner rim of floral tube, alternating with sepals, crinkled, pinnately veined, caducous ; stamens diplostemonous, sometimes reduced to a single whorl; gynoecium syncarpous, nectariferous tissue present or absent; style simple , slender, commonly exserted , stigma capitate or punctiform; ovary superior , infrequently semi-inferior, (2)-2-4(-many) locular, septa incomplete at apex or vestigial, reduced to thin threads, placentation axile , or globose and nearly free -central.  Fruits dry, thin or thick-walled capsules enclosed by persistent floral tube, dehiscing loculicidally, septicidally, or splitting irregularly.  Seeds numerous, obpyramidal, or oblong to obovoid and concave-convex, or bilaterally lenticular- compressed , winged or not, with inverted epidermal trichomes in seed coat; embro straight, cotyledons planar, auriculate or cordate , oily.  x = 8.

General Description
Notes on delimitation
  • Based on molecular evidence, the Combretaceae is sister to the Lythraceae and the Onagraceae. The three families constitute a major lineage of the Myrtales. 
  • Recent molecular work has led to the expansion of the family to include the satellite families Sonneratiaceae, Duabangaceae, Punicaceae and Trapaceae.
Number of genera
  • 15 native genera: Adenaria, Ammannia, Crenea, Cuphea, Diplusodon, Ginoria (including Haitia), Heimia, Lafoensia, Lourtella, Lythrum, Nesaea, Pehria, Physocalymma, Pleurophora, Rotala.
Status
  • Three non-native genera cultivated in the Neotropics: Lagerstroemia (crape myrtle), Lawsonia (henna), Punica (pomegranate).
General notes
  • Waiting publication: Haitia synonymized with Ginoria in Graham, S. A. (2009, in press).  Revision of the Caribbean Genus Ginoria (Lythraceae), including Haitia from Hispaniola.  Ann. Missouri Bot. Garden.
Distribution
Distribution in the Neotropics
  • Adenaria Kunth (1/1 sp.) - limited to South America and Central America.
  • Ammannia L. (4/25 spp.) - Old world and New World distribution.
  • Crenea Aubl. (2/2 spp.) - New World only.
  • Cuphea P. Browne (c. 240/c. 240 spp.) - limited to South America, Central America, Mexico, Caribbean, and United States.
  • Diplusodon
  • Pohl (85/85 spp.) - New World only.
  • Ginoria Jacq. (13/13 spp.) - present in Greater Antilles and Mexico.
  • Heimia Link (3/3 spp.) - limited to South America, Central America, Mexico, Caribbean, and United States.
  • Lafoensia Vand. (c. 5/c. 5 sp.) - limited to South America and Central America.
  • Lourtella
  • Graham, Baas, & Tobe (1/1 sp.) - New World only.
  • Lythrum L. (2/35 spp.) - Old world and New World distribution.
  • Nesaea Comm. (3/c. 50 spp.) - Old world and New World distribution.
  • Pehria Sprague (1/1 sp.) - limited to South America and Central America.
  • Physocalymma
  • Pohl (1/1 sp.) - New World only.
  • Pleurophora D. Don (c. 6/c. 6 spp.) - New World only.
  • Rotala L. (2/44 spp.) - Old world and New World distribution.
Diagnostic
Distinguishing characters (always present)
  • No unique synapomorphies.
Other important characters
  • Opposite entire leaves.
  • Flowers 4-6-merous, but 8-merous in Physocalymma, up to 16-merous in Lafoensia, perigynous, ovarysuperior, infrequently semi-inferior.
  • Crinkled petals, often fugacious.
  • Stamens 2-whorled (obdiplostemonous), deeply inserted.
  • Seeds in most New World genera with inverted trichomes in the epidermal cells of the seed coat that evert on wetting: trichomes spiraled in Cuphea, Lafoensia, Pehria, Pleurophora; trichomes straight in Ammannia, Crenea, Diplusodon, Ginoria, Heimia, Lythrum, Nesaea, Rotala.
Key differences from similar families
  • Onagraceae differ from Lythraceae by their viscidpollen threads and, excluding Ludwigia, also by epigynous flowers with inferior ovaries.
Useful tips for generic identification

Key to genera of Neotropical Lythraceae

1. Leaves glandular-punctate, the punctae non-secretory and orange-filled, turning black or secretory and translucent.
1. Leaves non-punctate, glabrous or variously indumented ... 4

2.  Leaves orange to black-punctate, non-secretory; inflorescences multi-flowered clusters ... 3
2.  Leaves translucent-punctate, secretory, blades varnished by resin; inflorescences 3-flowered axillary cymes ...Lourtella

3.  Flowers in compact umbelliform clusters; floral tube campanulate, greenish; capsule indehiscent...Adenaria
3.  Flowers in loose cymose clusters; floral tube cyathiform, deep red; capsule loculicidally dehiscent...Pehria

4.  Floral tubes campanulate to globose or cyathiform, about as long as to slightly longer than wide, actinomorphic... 5
4.  Floral tubes cylindrical, at least twice as long as wide, actinomorphic or zygomorphic... 13

5.  Seeds encircled by a broad, thin wing — 6
5.  Seeds not winged... 8

6.  Floral tubes caducous, distally pleated, (8-)10-12(-16)-merous; leaves with subapical abaxial porate chamber ...Lafoensia
6.  Floral tubes persistent, distally smooth, 6- or 8-merous; leaves normally developed at the apex, lacking a porate chamber ... 7

7.  Trees with strongly divaricate branching; flowers 8-merous; placenta appearing free -central ...Physocalymma
7.  Shrubs and subshrubs with opposite branching; flowers 6-merous; placenta bipartite, septa lunate ...Diplusodon

8.  Trees, shrubs, or subshrubs, 1-40 m ... 9
8.  Annual or perennial herbs, 2 cm - 2m, commonly less than 50 cm ... 1

9.  Stamens basifixed; petals cream-coloured; capsules indehiscent... Crenea
9.  Stamens dorsifixed; petals bright yellow, rose, purple, or white ... 10

10.  Petals bright yellow; flowers solitary; pedicels 0-4 mm ...Heimia
10.  Petals rose, purple, or white; flowers solitary and/or in axillary clusters; pedicels 10-40 mm ...Ginoria

11.  Capsules septicidally dehiscent, wall microscopically (10x) transversely striated; leaves decussate or whorled; leaf base tapered ...Rotala
11.  Capsules splitting irregularly or initially circumscissile, then irregular; wall microscopically smooth, without striations; leaf base auriculate or auriculate... 12

12.  Capsules splitting irregularly; leaf base auriculate...Ammannia
12.  Capsules initially circumscissile, then splitting irregularly; leaf base cordate...Nesaea

13.  Floral tubes actinomorphic;capsules dehiscing from the apex...Lythrum
13.  Floral tubes slightly to strongly zygomorphic, bilateral; capsules indehiscent or dehiscent dorsally by a longitudinal slit together with floral tube ... 14

14.  Stamens attached near base of floral tube, anthers basifixed; capsules indehiscent, placenta and seeds retained within ... Pleurophora
14.  Stamens attached at midlevel or higher in floral tube, anthers dorsifixed; capsules dehiscent dorsally by a longitudinal slit together with floral tube, placenta and seeds exserted...Cuphea

Notable genera and distinguishing features
  • Cuphea - largest genus of the family, c. 240 spp.  Endemic to New World.  Unique capsule dehiscence by a longitudinal slit with placenta and seeds emerging for seed dispersal.  Seed oils emphasize lauric acids and diversity of composition includes some with major percentages of caprylic acid.
  • Diplusodon - second largest genus of the family, c. 85 spp. Endemic to Brazil and adjacent Bolivia.
  • Heimia -  hallucenogenic, anti-inflammatory.
Literature
Important literature

Cavalcanti, T. B.  (in press). Revision of Diplusodon (Lythraceae).  Fl. Neotropica.

Graham, S. A.  1988.  Revision of Cuphea section Heterodon (Lythraceae).  Systematic Botany Monographs. 20: 1-168.

Graham, S. A.  1989.  Revision of Cuphea sect. Leptocalyx (Lythraceae).  Systematic Botany monographs 14: 43-76.

Graham, S. A. 1998.   Revision of Cuphea sect. Diploptychia (Lythraceae). Systematic Botany monographs 53: 1-96.

Graham, S. A.  2010.  Revision of the Caribbean genus Ginoria (Lythraceae), including Haitia from Hispaniola.  Annals of the Missouri Botanical Garden 97: 34-90.

Koehne, E.  1903.  Lythraceae.  326 pp. In: Engler, A. ed., Das Pflanzenreich IV. 216.

Lourteig, A.  1986.  Revision del genero Lafoensia Vandelli (Litraceas).  Mem. soc. ci. Nat. La Salle 45: 115-157.

Lourteig, A.  1986.  Revision del genero Crenea Aublet (Litraceas).  Caldasia 15: 121-142.

Lourteig, A.  1986.  Revision de dos secciones del genera Cuphea P. Browne (Lythraceae).  Phytologia 60: 17-55.

Lourteig, A.  1988.  Revision de Cuphea P. Browne seccion Heteranthus Koehne (Litraceas).  Mutisia 70: 1-20.

[FWTA]

Lythraceae, Hutchinson and Dalziel. Flora of West Tropical Africa 1:1. 1954

Habit
Herbs, shrubs or trees; leaves opposite or verticillate, rarely alternate; stipules absent or very small
Flowers
Flowers usually actinomorphic, hermaphrodite, solitary to paniculate
Calyx
Sepals united into a tube, valvate, sometimes with appendages between the lobes
Corolla
Petals present or absent, inserted towards the top of the calyx-tube, crumpled in the bud
Androecium
Stamens usually 4 or 8, or rarely more, inserted below the petals; filaments usually inflexed in bud; anthers 2-celled, opening lengthwise
Gynoecium
Ovary superior, sessile or shortly stipitate, completely or incompletely 2–6-celled (rarely 1-celled); style simple, variable in length; ovules numerous, on an axile placenta sometimes not extending to the top of the ovary
Fruits
Fruit usually capsular, opening by a transverse slit, by valves, or irregularly
Seeds
Seeds numerous, without endosperm; embryo straight
[FTEA]

Sonneratiaceae, G. R. Williams Sangai (East African Herbarium). Flora of Tropical East Africa. 1968

Habit
Trees or shrubs
Leaves
Leaves opposite, simple, entire, exstipulate
Flowers
Flowers hermaphrodite, actinomorphic, solitary or 3 together, axillary or terminal
Calyx
Calyx thick and leathery; tube campanulate; lobes 4–8, valvate
Corolla
Petals 4–8 or absent
Androecium
Stamens 12 to numerous, inserted on the calyx, often in several series; filaments free, at length reflexed; anthers reniform or oblong, medifixed, opening lengthwise
Gynoecium
Ovary free or adnate to the calyx-tube at the base, 4–many-locular; septa thin; ovules numerous, on thick axile placentas, ascending; style long, simple; stigma capitate
Fruits
Fruit a berry or a valvate capsule with 4–many locules and numerous seeds
Seeds
Seeds without endosperm; embryo with short leafy cotyledons
[FZ]

Sonneratiaceae, A. Fernandes. Flora Zambesiaca 4. 1978

Habit
Trees or shrubs, with normal and sometimes aerial roots (pneumatophores)
Leaves
Leaves opposite, petiolate, coriaceous, entire, exstipulate
Flowers
Flowers bisexual, actinomorphic, solitary or in 3s, axillary or terminal
Calyx
Calyx-tube campanulate, thickly coriaceous, 4–8-lobed, the lobes valvate
Corolla
Petals 4–8 or 0
Androecium
Stamens 12 to numerous, inserted on the calyx-tube usually in several series; filaments free; anthers reniform, medifixed, opening longitudinally
Gynoecium
Ovary free or adnate at the base to the calyx-tube, 4-many-locular; septa thin; style long; stigma subcapitate; ovules numerous, embedded in thick axile placentas, ascending
Fruits
Fruit a many-seeded berry or a capsule
Seeds
Seeds without endosperm; embryo with short leafy cotyledons
[FTEA]

Trapaceae, J. P. M. Brenan. Flora of Tropical East Africa. 1953

Habit
Aquatic floating herbs
Leaves
Leaves alternate, floating, rosetted, only present at the upper nodes; stipules small, scarious, cleft to base and thus apparently more than two per leaf; petiole spongy and more or less inflated about the middle; lamina rhombic to deltoid
Roots
Adventitious roots (?) submerged, paired but not opposite, one from either side of leaf-scar, chlorophyllose and thus leaf-like, pinnatisect into many filiform segments
Flowers
Flowers solitary from upper axils, pedunculate, hermaphrodite, regular
Calyx
Sepals, petals and stamens 4, latter perigynous
Corolla
Petals white
Gynoecium
Ovary half-inferior, bilocular; ovules pendulous, one per loculus
Fruits
Fruit a one-seeded, top-shaped drupe; pericarp soon disappearing; endocarp very hard, variously 2–4-horned, the horns derived from the persistent sepals
[FWTA]

Trapaceae, J.P.M.. Brenan. Flora of West Tropical Africa 1:1. 1954

Habit
Aquatic floating herbs
Leaves
Leaves alternate, floating, resetted, only present at the upper nodes; stipules small, scarious, cleft to base and thus apparently more than two per leaf; petiole spongy and more or less inflated about the middle; lamina rhombic to deltoid
Roots
Adventitious roots (?) submerged, paired but not opposite, one from either side of leaf-scar, chlorophyllose and thus leaf-like, pinnatisect into many filiform segments
Flowers
Flowers solitary from upper axils, pedunculate, hermaphrodite, regular
Calyx
Sepals, petals and stamens 4, latter perigynous
Corolla
Petals white
Gynoecium
Ovary half-inferior, bilocular; ovules pendulous, one per loculus
Fruits
Fruit a one-seeded, top-shaped drupe; pericarp soon disappearing; endocarp very hard, variously 2–4-horned, the horns derived from the persistent sepals
[FZ]

Trapaceae, J. P. M. Brenan. Flora Zambesiaca 4. 1978

Habit
Aquatic floating herbs
Leaves
Leaves alternate, floating, in rosettes, only present at the upper nodes; stipules small, scarious, cleft to base and thus apparently more than two per leaf; petiole spongy and more or less inflated about the middle; lamina rhombic to deltate
Roots
Adventitious roots (?) submerged, paired but not opposite, one from either side of petiole or leaf-scar, chlorophyllose and thus leaf-like, pinnatisect into many filiform segments; in those from upper nodes segments shorter or absent
Flowers
Flowers solitary, from upper axils, pedunculate, hermaphrodite, regular
Calyx
Sepals, petals and stamens 4, the latter perigynous
Corolla
Petals white
Gynoecium
Ovary half-inferior, bilocular; ovules pendulous, one per loculus
Fruits
Fruit a one-seeded, top-shaped drupe; pericarp soon disappearing; endocarp very hard, variously 2–4-horned, the horns derived from the persistent sepals

Images

Lythraceae J.St.-Hil. appears in other Kew resources:

First published in Expos. Fam. Nat. 2: 175. 1805 [Feb-Apr 1805] (as "Lythrariae") (1805)

Accepted by

  • APG IV (2016) http://dx.doi.org/10.1111/boj.12385

Sources

Flora Zambesiaca
Flora Zambesiaca
http://creativecommons.org/licenses/by-nc-sa/3.0

Flora of Tropical East Africa
Flora of Tropical East Africa
http://creativecommons.org/licenses/by-nc-sa/3.0

Flora of West Tropical Africa
Flora of West Tropical Africa
http://creativecommons.org/licenses/by-nc-sa/3.0

Kew Names and Taxonomic Backbone
The International Plant Names Index and World Checklist of Selected Plant Families 2019. Published on the Internet at http://www.ipni.org and http://apps.kew.org/wcsp/
© Copyright 2017 International Plant Names Index and World Checklist of Selected Plant Families. http://creativecommons.org/licenses/by/3.0

Neotropikey
Milliken, W., Klitgard, B. and Baracat, A. (2009 onwards), Neotropikey - Interactive key and information resources for flowering plants of the Neotropics.
http://creativecommons.org/licenses/by/3.0