Hyptis rhomboidea Mart. & Galeotti, Lamiaceae

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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Other Latin names:  Hyptis capitata var. mexicana Briq.; Hyptis capitata var. pilosa Briq.; Hyptis decurrens (Blanco) Epling

Common name(s): [more details]

Chinese: diao qiu cao

English: knobweed

Samoan: vao mini

Habit:  herb

Description:  "Perennial herb 2 dm to 2 m tall, the stems often slightly decumbent and rooting at nodes, angles moderately hirsute with several-celled, irregularly curved hairs, intermarginal surfaces glabrous, lower internodes shorter than subtending leaves, the upper progressively longer, often exceeding leaves; petioles narrowly winged, to 4 cm long, wings gradually ampliate, merging into blades; leaf blades rhomboidally ovate to rhomboid-lanceolate, 3-12 cm long, 1-4 cm wide, acute to attenuate at apex, cuneate at base, coarsely and irregularly serrate, dark green and sparsely hispid above, paler, markedly pellucid-punctate and with more or less appressed, several-celled, coarse hairs along veins beneath, intervenous surfaces glabrous; inflorescences semiglobose, borne on axillary peduncles 1-5 cm long, peduncles hirsute; bracts lanceolate to oblanceolate, 6-12 mm long, acute to acuminate at apex, somewhat more densely hirsute than leaves, entire; flowers crowded in heads, sessile; calyx tube about 1.5-2 mm long, antrorsely short-ciliate, equal or nearly so; fruiting calyces coarsely reticulate-veined between ribs; corolla about 4 mm long, white, bearing hairs to 1 mm long on outer surfaces of upper part of tube and lobes, tube about 2 mm long, gradually  ampliate upward; upper pair of stamens slightly shorter than lower; nutlets about 1 mm long" (Wiggins & Porter, 1971; pp. 402-404).

"This species is closely related to H. capitata Jacq., but has somewhat narrower and smaller bracts below the heads of the flowers, and broader and shorter calyx teeth"  (Wiggins & Porter, 1971; pp. 402-404).

Habitat/ecology:  In New Guinea, "a weed of roadsides, waste land and pastureas; quite unpalatable to livestock and so, if unchecked, soon becoming dominant in grazing land" (Henty & Pritchard, 1975; p. 105). Moist uplands in the Galápagos Islands (McMullen, 1999; p. 252).

Propagation:  Seed

Native range:  Mexico; naturalized elsewhere (GRIN).

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Ecuador (Galápagos Islands) Isabela Group	Isabela Island	introduced invasive	Charles Darwin Foundation (2008)
Ecuador (Galápagos Islands) Isabela Group	Volcán Alcedo, Isabela Island	introduced invasive	Charles Darwin Foundation (2008)
Ecuador (Galápagos Islands) Isabela Group	Volcán Sierra Negra, Isabela Island	introduced invasive	Charles Darwin Foundation (2008)
Ecuador (Galápagos Islands) San Cristóbal Group	San Cristóbal Island	introduced invasive	Charles Darwin Foundation (2008)
Ecuador (Galápagos Islands) Santa Cruz Group	Santa Cruz Island	introduced invasive	Charles Darwin Foundation (2008)
Ecuador (Galápagos Islands) Santiago Group	Santiago Island	introduced invasive	Charles Darwin Foundation (2008)
Guam Guam Island	Guam Island		Donnegan, Joseph A./Butler, Sarah L./Grabowiecki, Walter/Hiserote, Bruce A./Limtiaco, David (2004) (p. 23)
Papua New Guinea Bougainville Islands	Bougainville Island		Foreman, D. B. (1971) (p. 43)
Papua New Guinea Papua New Guinea (eastern New Guinea Island)	Papua New Guinea (eastern New Guinea Island)	introduced invasive	Henty, E. E./Pritchard, G. H. (1975) (p. 105) Established in a few lowland areas.

Pacific Rim
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
China China	China (People's Republic of)	introduced invasive	Zhengyi, Wu/Raven, Peter H./Deyuan, Hong (2013) Open waste areas. Guangdong, Guangxi.
China China	Hong Kong	native	Wu, Te-lin (2001) (p. 235) On hillslopes, on margin of forests.
Mexico Mexico	Mexico (United Mexican States)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Taiwan Taiwan Island	Taiwan Island	introduced invasive	Zhengyi, Wu/Raven, Peter H./Deyuan, Hong (2013) Open waste areas.

Comments:  Probably not native to the Galápagos Islands, possibly introduced, per Charles Darwin Research Station.

Control:  If you know of control methods for Hyptis rhomboidea, please let us know.