more images

Field guide to Tachia (free download)

Common name: 

Latin name and synonyms: Tachia Aubl.,  Hist. Pl. Guiane 75 (1775)

Species:  13 species

Distribution: tropical south America, primarily in the western and northern Amazon Basin and on the Guayana Shield; one species in Costa Rica.

Habitat: Lowland and middle elevation rainforests, savannas.

Characteristics: Small trees or shrubs, often with hollow and yellow branches. Leaves opposite, either with pinnate or arcuate venation.  Flower in leaf axils, without bracts, solitary, and sessile or nearly so, 5-merous, slightly zygomorphic. Calyx fused at base, sometimes more, yellow, tubular, sometimes keeled.  Corollas tubular to salvershaped, with long corolla tube, yellow, cream, orange, or greenish.  Stamens inserted far down in corolla tube, filaments of unequal length, anthers recurved after anthesis. Pollen in monads (single pollen grains).  Pistil with nectaries at base (disk), style long and slender, stigma bilamellate.  Capsules opening in two halves, woody. 

Evolution and related plants:  Tachia belongs to the Macrocarpaea clade in the tribe Helieae, and is most closely related to Macrocarpaea and Chorisepalum.

Economic uses:  Tachia is used in Brazil for medicinal purposes.

Notes: This is an easily recognized genus because of its solitary, axillary flowers, woody habit, and long corolla tubes. Ants are often living inside the hollow stems.

Accepted species (synonyms in parenthesis) and their distribution:

References and publications: 

Cobb, L. & P. J. M. Maas. 1998. A new species of Tachia (Gentianaceae) from Suriname. Brittonia 50: 11-18.

Maguire, B. & R. E. Weaver, Jr. 1975. The neotropical genus Tachia (Gentianaceae). J. Arnold. Arb. 56: 103-125.

Struwe, L., J. W. Kadereit, J. Klackenberg, S. Nilsson, M. Thiv, K. B. von Hagen, & V. A. Albert. 2002. Systematics, character evolution, and biogeography of Gentianaceae, including a new tribal and subtribal classification. Pp. 21-309. In: L. Struwe & V. A. Albert (eds.), Gentianaceae: Systematics and Natural History, Cambridge University Press, Cambridge.

Struwe, L., P. J. M. Maas, & V. A. Albert. 1997. Aripuana cullmaniorum, a new genus and species of Gentianaceae from white-sands of southeastern Amazonas, Brazil. Harvard Pap. Bot. 2: 235-253.

Struwe, L., P. J. M. Maas, O. Pihlar, & V. A. Albert. 1999. Gentianaceae. Pp. 474-542. In: P. E. Berry, K. Yatskievych, & B. K. Holst, editors. Flora of the Venezuelan Guayana, vol. 5. Missouri Botanical Garden, St. Louis. (images)

© Lena Struwe, 2005