Paul J.M. Maas & Hiltje Maas-van de Kamer
National Herbarium of the Netherlands (Wageningen branch), Wageningen, the Netherlands.
Herbs, perennial, rhizomatous, growing in or near water. Leaves alternate, tristichous, simple, basal, parallel-veined, V-shaped in transverse section, linear, sheathing basally, the margins often serrate. Inflorescences globose, terminal heads subtended by several leafy bracts, on long, 3- to 4-angled peduncles. Flowers bisexual, actinomorphic, sessile, small; tepals 6, free, chaffy, subequal; stamens 6, much exceeding the tepals, anthers longitudinally dehiscent, dithecal, basifixed, introrse; ovary superior, 3-locular, style 1, very short, stigmas 3, elongate, placentation axile, ovules 1-few per locule. Fruits 3-angled, loculicidal capsules. Seeds 1 per locule, fusiform, pointed at both ends.
Notes on delimitation
- The Thurniaceae are placed in the order Poales in the APG III system (Stevens, 2008; APG III, 2009).
- In Cronquist (1981) and Takhtajan (2009) we find the family in the Juncales, closely related to Juncaceae.
Distribution in the Neotropics
- The family consists of two genera with one ocurring in the Neotropics
- Thurnia Hook.f. (3 spp.) the Guianas and adjacent Amazon region, often on sandy soils in or near water.
Distinguishing characters (always present)
- Large herbs mostly growing in or near water.
- Leaves basal, linear, often sharply teethed.
- Inflorescences globose, terminal heads subtended by several leafy bracts.
- Flowers small, chaffy; seeds fusiform, pointed at both ends.
Key differences from similar families
1. Perianth present; fruit a capsule …. 21. Perianth mostly lacking or if present consisting of hairs, scales or bristles; fruit a nutlet …. Cyperaceae.2. Inflorescence a dense and large globose head on a long peduncle; leaf margins serrate; plants of the lowlands of the Guianas and adjacent Amazon region …. Thurniaceae2. Inflorescence differently shaped; leaf margins never serrate; plants of mountainous areas in the Neotropics …. Juncaceae
Number of genera
- Thurnia is native in the Neotropics and is not cultivated.
A.P.G. III. 2009. An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG III. Bot. J. Linnean Soc. 161: 105-121.
Cronquist, A. 1981. An integrated system of classification of flowering plants. Columbia University Press. New York
Kubitzki, K. 1998. Thurniaceae. In: Kubitzki, K. (ed.). The families and genera of vascular plants, vol. 4. Flowering Plants -Monocotyledons. Alismatanae and Commelinanae (except Gramineae), pp. 455-457. Springer Verlag, Berlin, etc.
Maas, P.J.M. & Westra, L.Y.Th. 2005. Neotropical Plant Families. A concise guide of vascular plants in the Neotropics. 3rd ed., p. 88. A.R.G. Gantner Verlag K.G., Ruggell.
Stevenson, D.W. 2004. Thurniaceae. In: Smith, N.P., Mori, S.A., Henderson, A., Stevenson, D.W., and Heald, S.V. (eds.). Flowering plants of the Neotropics. pp. 486-487. Princeton University Press, Oxford and Princeton.
Takhtajan, A. 1997. Flowering Plants. Second edition. Springer Verlag, Berlin.