1. Alismataceae Vent.

    1. This family is accepted.

[FTEA]

Alismataceae, Susan Carter. Flora of Tropical East Africa. 1960

Habit
Perennial, rarely annual, aquatic, swamp or marsh herbs, lactiferous
Rhizomes
Rhizome very short; roots short, fibrous
Leaves
Leaves erect, rarely floating or submerged, basal; petiole with an expanded, sheathing base; leaf-blade entire, linear-lanceolate to ovate, with a decurrent to sagittate base, acute to rounded apex
Inflorescences
Inflorescence compound or simple, of whorls of branches or flowers, rarely pseudo-umbellate or with solitary flowers; bracts 2 or 3 at the base of each whorl, and sometimes several bracteoles
Flowers
Flowers regular, bisexual or unisexual
Calyx
Sepals 3, persistent, herbaceous
Corolla
Petals 3, deciduous, rarely 0
Androecium
Stamens 3, 6, 9 or more; filaments filiform or flattened; anthers 2-celled, dehiscing longitudinally and laterally
Gynoecium
Carpels superior, free or joined at the base, 3–?, in a whorl or spiral, unilocular; style terminal or ventral; ovules 1, 2 or many, basal and erect, or situated on the ventral suture
Fruits
Fruit indehiscent
Seeds
Seeds oblong, indented laterally to follow the form of the horseshoe-shaped embryo, smooth, wrinkled or ridged, without endosperm
[FWTA]

Alismataceae, F.N. Hepper. Flora of West Tropical Africa 3:1. 1968

Habit
Perennial or annual marsh or aquatic herbs, erect, or rarely with floating leaves; leaves basal, with elongated petioles sheathing but open at the base and linear-lanceolate to ovate-rounded often sagittate blades, the principal nerves parallel with the margins and converging at the apex of the blade, the transverse nerves often close and parallel
Flowers
Flowers often whorled, racemose or paniculate, bisexual or rarely polygamous, actinomorphic
Nectaries
Torus flat to globose
Perianth
Perianth 2-seriate, the outer 3 imbricate, persistent, green and sepal-like, the inner 3 petaloid, imbricate and deciduous or rarely absent
Androecium
Stamens hypogynous, 6 or more, rarely 3, free; anthers 2-locular, extrorse
Gynoecium
Carpels free or rarely united at the base, sometimes in a single whorl; style persistent; ovules solitary or several, basal or on the inner angle
Fruits
Fruit a bunch or whorl of achenes, rarely dehiscing at the base
Seeds
Seeds curved, with horseshoe-shaped embryo; endosperm none
[NTK]

Pansarin, E.R. (2009). Neotropical Alismataceae.

Morphology
Description

Perennial , rarely annual aquatic, laticiferous herbs. Roots fibrous , sometimes adventitious . Stem short, sometimes corm -like rhizomes or pseudostolons present. Leaves basal , alternate , spiral or in two ranks, sessile or petiolate , simple , sheathing at base, emergent or more rarely submerged or sometimes with floating blade ; petiole terete to triangular between whorls; blade with pellucid marking in some species of Echinodorus Rich. & Engelm. ex A.Gray and Helanthium (Benth. & Hook.f.) Engelm. ex J.G.Sm.. Inflorescence scapose, usually raceme -like or panicle -like cymes with numerous whorls along a complex system of branches, sometimes umbellate through reduction to one whorl or sometimes reduced to a solitary flower . Flowers hermaphrodite or unisexual (then plants monecious or dioecious ), actinomorphic , hypogynous, 3- merous , with perianth differentiated into sepals and petals; sepals 3, free , persistent , sometimes coriaceous and with longitudinal ribs (Echinodorus and Helanthium); petals 3, free , delicate, usually white, rarely pink, sometimes with a yellow or purple spot at the base; stamens 6 to numerous, filaments distinct, anthers extrorse, rimose; gynoecium apocarpous, with 3 to many carpels distributed along a convex receptacle , carpels generally 1-ovulate and with basal placentation, stigma apical or with a lateral or gynobasic persistent style . Fruit an achene or more rarely a follicle , sometimes with longitudinal ribs (Echinodorus and Helanthium). Seeds U-shaped, with or without glands , endosperm absent.

Distribution
Distribution in the Neotropics
  • Alismataceae includes 12 genera and about 80 species distributed among tropical and subtropical regions of both hemispheres.
  • Three genera occur in the Neotropics: Sagittaria Rupp. ex L., Echinodorus and Helanthium (a genus segregated from Echinodorus).
  • The center of diversity of Echinodorus is the Neotropical region. All species of this genus occur in the Neotropics.
  • Helianthium is a genus endemic to the Neotropics, occurring mainly in South America.
  • Sagittaria is a genus distributed predominantly in the western hemisphere, with about 12 species occurring in the Neotropics. Some North American species are cultivated as pond ornamental plants.
Diagnostic
Other important characters
  • White or more rarely pink flowers with apocarpous gynoecium and generally one basalovule per carpel.
Distinguishing characters (always present)

Alismataceae are distinguishable on the basis of the presence of:

  • Laticifers.
  • The stomata with parallel division.
  • The pollen grains commonly 2-porate to polyporate.
  • The embryo strongly curved.
Useful tips for generic identification

Key to genera of Neotropical Alismataceae

1. Rhizomatous herbs. Inflorescence a raceme-like or panicle-like cyme or a panicle-like cyme with several whorls — 2
1. Pseudostoloniferous herbs. Inflorescence umbelliform with up to three whorls. Flowers hermaphrodite with 6 or more rarely 9 stamens and 10-20 carpels. Achenes with 3-4 longitudinal ribs — Helanthium

2. Flowers hermaphrodite or pistillate (gynodioecious species), with numerous stamens, versatile anthers, and more than 20 carpels. Achenes ribbed, not winged — Echinodorus
2. Flowers unisexual (monoecious plants), sepals without longitudinal ribs, with numerous stamens, basifixed anthers, and more than 20 carpels. Achenes not ribbed, winged — Sagittaria

Key differences from similar families

Alismataceae can be distinguished from Limnocharitaceae on the basis of:

  • Their white or pink flowers (vs. yellow flowers in Limnocharitaceae).
  • Generally one ovule per carpel (vs. many ovules per carpel).
  • Basal placentation (vs. laminar placentation).
  • Presence of achenes (vs. follicles).
General Description
General notes
  • Some native species includes aquarium and pond ornamental plants.
  • Some species of Sagittaria have an edible rhizomatous stem.
  • Leaves of Echinodorusgrandiflorus are used in popular medicine.
  • Pollen collecting bees pollinate many species of Echinodorus. Sagittaria and some species of Echinodorus present floral nectaries. The floral nectar is secreted from the base of petals, stamens or carpels.
Status
  • All three genera occurring in the Neotropics are native.
Notes on delimitation
  • Some authors, based on morphological and molecular analysis, include both genera Limnocharis Bonpl. and Hydrocleys Rich. (Limnocharitaceae) within Alismataceae sensu lato, but this is not a consensus.
  • According to Lehtonen and Myllys (2008), only Limnocharis is nested within Alismataceae .
  • Furthermore, in the most treatments Limnocharitaceae and Alismataceae have been considered as distinct families because Alismataceae sensu stricto form a monophyletic group.
Literature
Important literature

Fassett, N.C. 1955.  Echinodorus in the American tropics. Rhodora 57: 133-156, 174-188, 202-212.

Haynes, R.R. & Holm-Nielsen, L.B. 1985.  A generic treatment of Alismatidae in the Neotropics with special reference to Brazil. Acta Amazônica, Suppl. 15: 153-193.

Haynes, R.R. & Holm-Nielsen, L.B. 1986.  191. Alismataceae. In: G. Harling & L. Andersson (eds.) Flora of Ecuador 26: 1-24.

Haynes, R.R. & Holm-Nielsen, L.B. 1994.  The Alismataceae. Flora Neotropica Monogr. 64: 1-112.

Haynes, R.R. & Holm-Nielsen, L.B. 1995.  Alismataceae. In: P.E. Berry, B.K. Holst & K. Yatskievych (eds.). Flora of Venezuelan Guayana. 2: 377-383.

Lehtonen, S. 2006.  Phylogenetics of Echinodorus (Alismataceae) based on morphological data. Botanical Journal of the Linnean Society 150: 291-305.

Lehtonen, S. & Myllys, L. 2008.  Cladistic analysis of Echinodorus (Alismataceae): simultaneous analysis of molecular and morphological data. Cladistics 24: 218-239.

Lot, H.A. & Novelo, R.A. 1994.  Alismataceae. In: G. Davidse, M. Souza S. & A.O. Chater (eds.) Flora Mesoamericana  6: 3-8. México, D. F.: Universidad Nacional Autonoma de México.

Pansarin, E.R. & Amaral, M.C.E., 2005.  Alismataceae. In: M.G.L. Wanderley, G.J. Shepherd, A.M. Giulietti & T.S. Melhem (eds.) Flora Fanerogâmica do Estado de São Paulo. Rima, São Paulo, pp. 1-10.

Pansarin, E.R. 2008.  Reproductive biology of Echinodorus longipetalus (Alismataceae): sexual morphs, breeding system and pollinators Aquatic Botany 89: 404-408.

Rataj, K. 1978.  Alismataceae of Brazil. Acta Amazônica, Supl. 8: 1-53.

Rogers, G.K. 1983.  The genera of Alismataceae in the Southeastern United States. Journal of Arnold Arboretum 64: 383-420.

Seubert, M. 1847.  Alismataceae. In: C.F.P. Martius & A.G. Eichler (eds.) Flora Brasiliensis. 3(1): 101-112, tabs. 12-16. Typographia Regia, Monachii.

[NTK]

Pansarin, E.R. (2009). Neotropical Limnocharitaceae.

Morphology
Description

Perennial , laticiferous and glabrous aquatic herbs growing in fresh water; hermaphrodite . Roots fibrous , sometimes adventitious . Stems short, sometimes fleshy , rhizomes or stolons present. Leaves basal or alternate , petiolate , simple , sheathing at base, emergent or more rarely submerged or sometimes with floating blade ; petiole terete to triangular; blade orbicular to lanceolate with entire margins and reticulate venation ; apex obtuse to rounded - acute , with an apical hydathode ; base cordate to attenuate. Inflorescence scapose, umbellate, generally erect , emergent or floating; bracts elliptic to acuminate , erect , membranaceous, much shorter than pedicel . Flowers hermaphrodite , actinomorphic , hypogenous, 3- merous , pedicellate, with perianth differentiated into calyx and corolla ; sepals 3, free , persistent , sometimes coriaceous , enclosing fruits; petals 3, free , delicate, ephemeral, yellow, sometimes with a dark spot at  base (Hydrocleys Rich.); stamens 3 to numerous, in one or more series, the more external frequently reduced to staminodes, filaments distinct, anthers rimose, linear , basifixed, with two locules ; gynoecium apocarpous, with 3 to many carpels distributed along a receptacle , carpels free or coherent at base, 1-loculate, with many ovules and laminar placentation, stigma linear , style conspicuous or absent. Fruit a membranaceous follicle with adaxial dehiscence; seeds U-shaped, numerous; endosperm absent.

Distribution
Distribution in the Neotropics
  • Hydrocleys  is distributed among tropical and subtropical regions of Central and South America, and south of Mexico.
  • Limnocharis is endemic to the Neotropics, occurring mainly in South America.
Diagnostic
Distinguishing characters (always present)

Limnocharitaceae is distinguishable on basis in the presence of:

  • Laticifers.
  • Flowers hermaphrodite with yellow petals, sometimes with dark spots on the base.
  • Fruits follicles.
  • Numerous seeds with ornamentation (pubescent or costate).
  • Large, strongly curved embryos.
Other important characters
  • Gynoecium apocarpous.
  • Many ovules per carpel.
  • Dehiscent and membranaceous fruits with laminar placentation.
Key differences from similar families
  • Limnocharitaceae can be distinguished from Alismataceae based on their yellow flowers, many ovules per carpel, laminar placentation and presence of follicles. Members of Alismataceae possess white or pink flowers, generally one ovule per carpel, basal placentation, and achenes.
  • Limnocharitaceae can be distinguished from Butomaceae on the basis of the presence of latex and large, strongly curved embryos. Members of Butomaceae possess straight embryos and lack laticifers.
Useful tips for generic identification
  • Limnocharis - Leaves glaucous; carpels numerous, semicircular; styles absent; seeds with transversal ribs.
  • Hydrocleys -Leaves light green; carpels 3-8, linear-lanceolate; styles conspicuous; seeds glandular-pubescent.
General Description
Status
  • Both genera (Limnocharis and Hydrocleys) are native to the Neotropics.
General notes
  • Some native species include aquarium and ornamental pond plants.
Notes on delimitation
  • Some authors, based on morphological and molecular analysis, include Limnocharitaceae within Alismataceaesensu lato, but this is not a consensus. According to Lethonen and Myllys (2008), only Limnocharis Humb. & Bonpl. is nested within Alismataceae. Furthermore, in most treatments the Limnocharitaceae and Alismataceae have been considered as distinct families because the Alismataceaesensu stricto form a monophyletic group.
  • Limnocharitaceae and related families (Alismataceae and Butomaceae) are considered as primitive monocotyledons.
Number of genera
  • Limnocharitaceae includes three genera and about seven species distributed among tropical regions of both hemispheres.
  • Two genera occur in the Neotropics: Limnocharis and Hydrocleys.
Literature
Important literature

Haynes, R. R. & Holm-Nielsen, L. B. 1986. 192. Limnocharitaceae. In G. Harling, & L. Andersson (eds) Flora of Ecuador 26: 25-34.

Haynes, R. R. & Holm-Nielsen, L. B. 1992. The Limnocharitaceae. Fl. Neotrop. Monogr. 56: 1-34.

Lehtonen, S. & Myllys, L. 2008. Cladistic analysis of Echinodorus (Alismataceae): simultaneous analysis of molecular and morphological data. Cladistics 24: 218-239.

Novelo R., A. & Lot H., A. 1994. Limnocharitaceae. In G. Davidse, M. Sousa S. & A. O. Chater (eds) Flora Mesoamericana. México, D. F.: Universidad Nacional Autónoma de México. v. 6, p. 8-9.

Pansarin, E. R. & Amaral, M. C. E. 2002. Limnocharitaceae. In M. G. L. Wanderley, G. J. Shepherd & A. M. Giulietti (eds) Flora Fanerogâmica do Estado de São Paulo. São Paulo, Hucitec, v. 2. p.155-157.

Pedersen, T. M. & Klein R. M. 1976. Limnocaritáceas. In P. R. Reitz (ed.) Flora Ilustrada Catarinense, parte I, fasc. Limn. Itajaí, Herbário 'Barbosa Rodrigues', 9p., est. 1.

Seubert, M. 1842. Butomaceae. In C. F. P. Martius & A. G. Eichler (eds) Flora brasiliensis. Monachii, Typographia Regia, v. 3, pt. 1, p. 115-118, tabs. 13-16.

Images

Alismataceae Vent. appears in other Kew resources:

First published in Tabl. Regn. Vég. 2: 157. 1799 [5 May 1799] (1799)

Accepted by

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

Sources

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