Juncaginaceae Juss.

This family is accepted.


Haigh, A. (2009). Neotropical Juncaginaceae.


Aquatic herbs, emergent, grass-like, underground rhizomes and erect stems usually present. Leaves alternate , basal , simple , sessile ; tubular sheath present, adnate proximally to blade ; ligule present at apex of sheath (a few millimeters long); blades linear , terete to dorsiventrally flattened. Inflorescences terminal on elongate scapes, spikes, solitary pistillate flowers present in Lilaea Bonpl. (in addition to spikes), these axillary . Flowers actinomorphic or zygomorphic , bisexual or sometimes unisexual in Liliaea (plants polygamous); perianth absent, or tepals 1, or 6 in 1-2 series, distinct; androecium of 1, 4, or 6 stamens, sometimes absent, the anthers sessile or subsessile; gynoecium weakly connate in Triglochin L., the ovaries superior , the carpels 3 or 6 (fertile) in Triglochin, or 1 in Lilaea, 3 sterile carpels alternating with fertile carpels when only 3 fertile carpels present (in Triglochin), the styles absent in Triglochin and present in Lilaea; placentation basal , the ovules 1 per carpel . Fruits schizocarps, the 3 or 6 fertile carpels eventually separating into 1-seeded nutlets, the nutlets 3- winged in Lilaea. Seeds solitary; embryo straight.

N.B. Lilaea has up to four types of flowers on one plant. These include perfect flowers with tepals present and the style 0.5-2 mm long or without tepals and the style 0.2-30 cm long. The latter type is solitary in the leaf axils. The remaining ones are in spikes.

Haynes 2004

Distribution in the Neotropics

A subcosmopolitan family of 4 genera and c. 12 species.  Two genera comprising 4 species occur in the Neotropics, and one genus (Tetroncium Willd.) in southern South America.

  • Triglochin L.:  12 species, cosmopolitan, with about 4 species native to the coastal marshes of the Neotropics.
  • Lilaea:  monospecific (L. scilloides (Poiret) Hauman) native to temperate and tropical montane marshes, from Canada to Chile and Argentina.
  • Tetroncium Willd.:  monospecific (T. magellanicum Willd.) occurs outside the Neotropics, but in Tierra del Fuego, Patagonia, and the Falkland Islands.
Distinguishing characters (always present)
  • Aquatic herbs, emergent, grasslike.
  • Leaves basal, linear; sheath present.
  • Fruits schizocarps or nutlets.
Other important characters
  • Flowers with perianth absent, or tepals 1, or 6 in 1 or 2 series.
  • Inflorescences on scapes, terminal spikes or of solitary axillary flowers.
Useful tips for generic identification

Key to genera of Neotropical Juncaginaceae

1. Flowers both distally in scapose, spikelike racemes, these perfect, pistillate and staminate, and basally on the scape in leaf axils, these pistillate and 1-carpellate — Lilaea
1. All flowers distally in spikelike racemes; carpels 3, 4 or 6 — 2

2. Flowers 3-merous — Triglochin
2. Flowers 2-merous; southern S. America —Tetroncium

General Description


General notes
  • The Juncaginaceae occupy a variety of habitats. Lilaea can be found in high mountain meadows of the Andes. Triglochin usually occurs in marshes that are brackish or have high concentrations of marl.
  • Plants are often extremely abundant in soils so heavily laden with marl or salts that the soil surface is white, especially on high plateaus.
Notes on delimitation
  • The Juncaginaceae are placed within the Alismatales with Hydrocharitaceae and Potamogetonaceae.
Important literature

Haynes, R.R., 2004. Juncaginaceae. Pp. 452-453. In: Smith, N., Mori, S.A., Henderson, A., Stevenson, D.W. & Heald, S.V. (eds.). Flowering Plants of the Neotropics. New York Botanical Garden, Princeton University Press, Princeton.

Haynes, R.R., Les, D.H. & Holm-Nielsen L.B., 1998. Juncaginaceae. In: K. Kubitzki (ed.), The families and genera of vascular plants 4: 260-263.


Juncaginaceae, D. M. Napper. Flora of Tropical East Africa. 1971

Morphology General Habit
Annual or perennial herbs
Vegetative Multiplication Rhizomes
Rhizomes short or long, or base bulbous; stolons rarely present
Morphology Leaves
Leaves basal, linear, flat or semiterete
Morphology Reproductive morphology Inflorescences
Inflorescence a spike or raceme
Morphology Reproductive morphology Flowers
Flowers regular and bisexual, sometimes imperfect or unisexual
Morphology Reproductive morphology Flowers Perianth
Perianth of 6 similar segments in 2 whorls, deciduous, herbaceous; tepals free or connate below
Morphology Reproductive morphology Flowers Androecium
Stamens 6, rarely 4, in 2 series opposite the tepals; filaments usually short; anthers 2-thecous, dehiscing longitudinally, extrorse
Morphology Reproductive morphology Flowers Gynoecium
Carpels superior, free or axially connate, 6, or 3 + 3 undeveloped, unilocular; ovules 1 or 2, collateral, basal, erect; stigmas sessile or subsessile, plumose or papillose
Morphology Reproductive morphology Fruits
Mericarps 3–6, indehiscent, free or axially connate

Juncaginaceae Juss. appears in other Kew resources:

First published in Gen. Pl. [Jussieu] 43. 1789 [4 Aug 1789] (1789)

Accepted by

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

  • Flora of Tropical East Africa

    Flora of Tropical East Africa

  • Kew Names and Taxonomic Backbone

    The International Plant Names Index and World Checklist of Selected Plant Families 2022. 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.