Neotropical Costaceae

Paul J.M. Maas and Hiltje Maas-van de Kamer

National Herbarium, Wageningen University Branch, the Netherlands. 


Perennial often large-sized herbs, with rhizomes. Stems terete, straight or spirally contorted, containing an acid juice. Leaves spirally arranged, with closed sheaths and a truncate or 2-lobed ligule. Inflorescence a spike, terminal on a leafy stem or sometimes on a separate leafless, basal shoot, rarely flowers solitary in the axils of the upper leaves (Monocostus K.Schum.); bracts often brightly coloured, coriaceous to herbaceous, imbricate, each subtending 1 flower, with a linear callus just below the apex; bracteole 1, folded or tubular. Flowers zygomorphic; calyx tubular, 3-lobed; petals 3, connate into a distinct tube; fertile stamen 1, petaloid, anther 1, usually attached at the middle; labellum equaling or much exceeding the corolla, tubular or horizontally spreading; style 1, filiform, lying close to the stamen and embraced by the thecae, stigma 1, 2-lamellate with a 2-lobed appendage or cup-shaped and unappendaged, margins ciliate; ovary inferior, 2-3-locular, with 2 septal nectarial glands towards the apex, placentation axile, ovules many, anatropous. Fruit a white capsule, 3- or 2-locular, crowned by the persistent calyx, often irregularly and tardily dehiscent. Seeds many, angular-ovoid to 4-sided, with a white aril, glossy black or brown.

Notes on delimitation

  • Costaceae were formerly treated as a subfamily of Zingiberaceae (Costoideae), but recent research revealed that they should be treated as a family of its own. The family belongs in the Zingiberales.

Distribution in the Neotropics

Family: From Mexico in the North to S Brazil and N Paraguay in the South, also present in the West Indian Islands.


  • Chamaecostus C.D.Specht & D.W.Stev. - Colombia, Venezuela, the Guianas, and Amazonian and SE Brazil, and Bolivia.
  • Costus L. - throughout he Neotropics.
  • Dimerocostus Kuntze (3 spp.) - from Honduras in he North to Peru and Bolivia in the South.
  • Monocostus (1 sp.) - Eastern Peru.

Distinguishing characters (always present)

Other important characters

Key differences from similar families

Costaceae have various flower characters in common with Zingiberaceae, but they differ by having:

  • Non-aromatic leaves.
  • Closed leaf sheaths.

Number of genera

  • Chamaecostus (7 spp.)
  • Costus (ca. 50 spp.)
  • Dimerocostus (2 spp.)
  • Monocostus (1 sp.)

Useful tips for generic identification

Key to genera of the Neotropical Costaceae

1. Flowers solitary in the axils of the upper leaves...Monocostus
1. Flowers in a terminal spike... 2

2. Ovary 2-locular; bracteole tubular...Dimerocostus 
2. Ovary 3-locular; bracteole folded or tubular... 3

3. Low or very small, occasionally acaulescent plants, never exceeding 1 m in height; bracts herbaceous to chartaceous, green or yellow; bracteole tubular, bicarinate at the abaxial side; stigma cup-shaped...Chamaecostus
3. Tall, gigantic, or low plants, usually over 1 m tall; bracts coriaceous, rarely chartacous, red, orange, yellow or green; bracteole folded; stigma 2-lamellate, always provided with a dorsal 2-lobed appendage...Costus

Notable genera and distinguishing features

  • Monocostus is unique in the family in having solitary, axillary flowers; it is endemic to Eastern Peru, where it grows in forests on limestone.
  • Chamaecostus has been recently separated from Costus by Specht et al. (2001, 2006) based on molecular evidence. Formerly it had been placed (see Maas, 1972) in Costus subgenus Cadalvena Fenzl.


  • All genera are native.

General notes

The petaloid labellum of Costaceae has been supposed to consist of 5 staminodes.

Important literature

Larsen, K. 1998. Costaceae. In: K. Kubitzki  (ed.), The families and genera of vascular plants 4: 128-132.

Maas, P.J.M. 1972. Costoideae (Zingiberaceae). Flora Neotropica Monograph 8: 1-140.

Maas, P.J.M. 1972. Renealmia (Zingiberaceae- Zingiberoideae). Costoideae (Additions) (Zingiberaceae). Flora Neotropica Monograph 18: 162-219.

Specht, C.D. 2006. Systematics and evolution of the tropical monocot family Costaceae (Zingiberales): A multiple dataset approach. Syst. Bot. 31: 89-106.

Specht, C.D., & Stevenson, D.W. 2006. A new phylogeny-based generic taxonomy for the monocot family Costaceae (Zingiberales). Taxon 555: 153-163.

Specht, C.D., Kress, W.J., Stevenson, D.W., & DeSalle, R. 2001. A molecular phylogeny of Costaceae (Zingiberales). Mol. Phyl. Evol. 21: 333-345.

How to cite

Maas, P.J.M. & Maas-van de Kamer, H. (2009). Neotropical Costaceae. In: Milliken, W., Klitgård, B. & Baracat, A. (2009 onwards), Neotropikey - Interactive key and information resources for flowering plants of the Neotropics.