From the Greek stachys, a spike, and tarphetios, thick, referring to the thick spikes of these plants.

Snakeweeds.

Herbs or low shrubs. Stem almost terete or tetragonal. Leaves simple, decussately opposite, petiolate. Inflorescence terminal, spicate, pedunculate; spikes elongate, indeterminate. Flowers bracteate, sessile, embedded in inflorescence axis (rachis), zygomorphic; bracts sessile. Calyx persistent, tubular, 4- or 5-dentate at apex. Corolla deciduous, tubular below, 5-lobed at the top; tube cylindric; lobes subequal, spreading. Stamens 4, included, inserted about middle of corolla tube; anterior stamens 2, fertile, with small filaments and non-appendaged anthers; posterior (or lateral) stamens 2, sterile, reduced to staminodes. Ovary 2-locular, each with one parietal ovule; style filiform; stigma capitate. Fruit schizocarpic, splitting into two 1-seeded mericarps. Seeds without endosperm.

A genus of about 90 species and many infraspecific and hybrid taxa, widely distributed in tropical and subtropical America, with a few weedy species naturalised in tropical and subtropical Africa, Asia and Australia. Six species naturalised in Australia, introduced from tropical America. Two are putative hybrids.

Details on the weed status, habitat, life cycle, dispersal and other properties of Stachytarpheta species are provided by Parsons & Cuthbertson (2001: 634–637).

Stachytarpheta Vahl, Enumeratio Plantarum 1: 205 (1804). Type: S. jamaicensis (L.) Vahl, typ. cons.

Vermicularia Moench, Supplementum ad Methodum Plantas 150 (1802), nom rej. Type: V. decurrens Moench.

Cymburus Salisb., Paradisus Londinensis 1(2): 49 (1806). Type: C. mutabilis (Jacq.) Salisb.

The name Stachytarpheta indica has been historically misapplied to several other species of Stachytarpheta, and although S. indica has been classified as an invasive weed by the Northern Australia Quarantine Strategy (NAQS) (Brown et al. 2008), evidence indicates that it does not occur in Australia (Chandler et al. 2014). Chandler et al. (2014) discuss a number of taxonomic issues in the genus, and provide a table of a major distinguishing characters used in the three most relevant taxonomic publications to distinguish between Stachytarpheta cayennensis, S. indica, S. jamaicensis and S. urticifolia.

Stachytarpheta species can invade disturbed areas and become serious weeds, particularly of sown pastures (Kleinschmidt & Johnson 1977, Parsons & Cuthbertson 2001, Chandler et al. 2014).

Adedeji, O. (2012). Systematic significance of trichomes and foliar epidermal morphology in the species of Stachytarpheta (Verbenaceae) from Nigeria. Thaiszia Journal of Botany 22: 1–31.

Backer, C.A. & Bakhuizen van der Brink, R.C. Jr (1965). Stachytarpheta, Flora of Java (spermatophytes only) 2: 597–598.  (NVP Noordhoff: Netherlands).

Bailey, F.M. (1883). Stachytarpheta, in A Synopsis of the Queensland Flora, p. 376 (J.C. Beal, Government Printer: Brisbane).

Bailey, F.M. (1901). Stachytarpheta, in The Queensland Flora 4: 1172. (H.J. Diddams & Co.: Brisbane).

Barker, R.M. & Telford, I.R.H. (1993). Verbenaceae, in George, A.S. et al. (eds), Flora of Australia. Volume 50, Oceanic Islands 2, pp. 360–367. (Australian Government Publishing Service: Canberra).

Bentham, G. (1876). Stachytarpheta, in Bentham, G. & Hooker, J.D., Genera Plantarum 2(2): 1145. (L. Reeve & Co.: London).

Briquet, J. (1895). Stachytarpheta, in Engler, A. & Prantl, K., Die Naturlichen Pflanzenfamilien 4(3a): 154–155. (Engelmann: Leipzig, Germany).

Brown, L., Johnson, H. & Raphael, B. (2008). Northern Australia Quarantine Strategy: weeds target list. Bureau of Rural Sciences report. (Australian Government: Canberra).

Chandler, G.T., Westaway, J.O. & Conn, B.J. (2014). Taxonomic uncertainty of Stachytarpheta (Verbenaceae) in the Asia–Pacific and implications for invasive weed recognition and management. Telopea 16: 83–87 & 93. Available in PlantNET via http://plantnet.rbgsyd.nsw.gov.au/Telopea/index.php

Kleinschmidt, H.E. & Johnson, R.W. (1977). Weeds of Queensland. (S.R. Hampson, Government Printer, Queensland).

Munir, A.A. (1992). A taxonomic revision of the genus Stachytarpheta Vahl (Verbenaceae) in Australia. Journal of the Adelaide Botanic Gardens 14(2): 133–168.

Parsons, W.T. & Cuthbertson, E.G. (2001). Noxious Weeds of Australia 2nd edn. (CSIRO Publishing: Collingwood, Vic.).

Rye, B.L. (1992). Stachytarpheta, in Wheeler, J.R. (ed.) et al., Flora of the Kimberley Region, p. 792. (Department of Conservation and Land Management: Como, W.A.).

Schauer, J.C. (1847). Stachytarpheta, in de Candolle, A.P. (ed.), Prodromus Systematis Naturalis Regni Vegetabilis 11: 561–572. (Fortin, Masson et Sociorum: Paris).

Stanley, T.D. (1986). Verbenaceae, in T.D. Stanley & E.M. Ross, Flora of South-eastern Queensland 2: 364–374. (Queensland Department of Primary Industries: Brisbane).

Swarbrick, J.T. (1984). Weeds of Australia. 4 Verbenaceae - the lantanas, fog fruit, verbenas and snakeweeds, Part 3. The snakeweeds. Australian Weeds 3: 20–22.

Further useful references may be found within those cited above. 

Published December 2018.