Strobilanthes hamiltoniana (Steud.) Bosser & Heine, Acanthaceae

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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Other Latin names:  Diflugossa colorata (Nees) Bremek.; Goldfussia colorata Nees; Ruellia hamiltoniana Steud.

Common name(s): [more details]

Chinese: cha hua cao

Habit:  shrub

Description:  "Shrubs 0.5-1.5 m tall, much branched, anisophyllous. Stems 4-angled, sulcate, glabrous. Leaves petiolate or apical ones sessile or subsessile; petiole (0-) 0.8-5 (-8) cm, glabrous; leaf blade lanceolate to ovate, smaller pair at least 2/3 size of larger one, 5-19 x 2-8.5 cm, glabrous, densely covered with linear cystoliths, secondary veins 4-7 on each side of midvein, base oblique to rarely slightly oblique and attenuate or on very large leaves subcordate, margin serrulate, apex acuminate. Inflorescences axillary or terminal, panicles, to 30 cm, much branched; rachis angled at ca. 60°, glabrous or rarely pubescent, gland-tipped in fruit; bracts green, broadly obovate, 3-5 x ca. 2 mm, concave, caducous, glabrous, becoming gland-tipped in fruit, margin entire, apex retuse; bracteoles green, oblanceolate to narrowly elliptic, 3-4 x ca. 1 mm, concave, caducous, glabrous, margin entire, apex retuse. Flowers solitary on each node, distant on rachis. Pedicel 1.5-5 mm, glabrous. Calyx 8-10 mm, accrescent to ca. 1.3 cm in fruit, glabrous, sometimes apically gland-tipped pubescent, becoming densely gland-tipped in fruit, 5-lobed almost to base; lobes narrowly elliptic with one longer than others, apex acute to sometimes retuse. Corolla white, lilac, or (in cultivated forms) deep pink with a white tube, 3.5-4 cm, subventricose, outside glabrous, inside glabrous except for trichomes retaining style; tube basally cylindric and ca. 2 mm wide for ca. 1.3 cm then slightly ventricose and gradually widened to 1.4-1.8 cm at mouth; lobes ovate, 4-5 x ca. 6 mm, apex rounded to retuse. Stamens 4, included; filaments glabrous; shorter filament pair ca. 1 mm, equal; longer filament pair 7-9 mm, unequal, erect; anther thecae white, spherical, ca. 1.2 mm in diam., partially recurved; pollen type 3. Ovary ca. 2.5 mm, glabrous; style ca. 3.8 cm, sparsely pubescent. Capsule green then dark purple, fusiform, 1-1.5 cm, glabrous or with gland-tipped trichomes, 4-seeded. Seeds ovate in outline, ca. 3 x 2 mm, with long trichomes; areola small"  (Flora of China online).

Habitat/ecology:  "Widely naturalized on La Réunion and Mauritius in native and secondary wet vegetation between 900 m and 1500 m elevation, covering approximately 1000 ha"  (Meyer & Lavergne, 2004; p. 337).

Propagation:  Seed (rarely), vegetatively (Meyer & Lavergne, 2004; p. 346).  "An ornamental plant. It is widely cultivated in tropical countries and in conservatories in temperate climates. The species is sometimes naturalized, occasionally becoming an invasive weed as on the island of Réunion. Cultivated plants and plants of cultivated origin seem always to be glabrous, pink-flowered, and sterile with dispersal being by cuttings or shoots broken off by grazing animals"  (Flora of China online).

Native range:  Bhutan, China (Xizang) northeastern India, Myanmar, Nepal; naturalized elsewhere; cultivated throughout the tropics (GRIN).

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
French Polynesia Society Islands	Tahiti Island	introduced cultivated	Florence, J./Chevillotte, H./Ollier, C./Meyer, J.-Y. (2013) Voucher cited: J. Florence 2669 (PAP) Cultivée
New Caledonia New Caledonia	New Caledonia Islands	introduced	Comité français de l'Union Internationale pour la Conservation de la Nature en France (2013) Potentiellement envahissant
New Caledonia New Caledonia Archipelago	Île Grande Terre	introduced invasive cultivated	MacKee, H. S. (1994) (p. 8) As Diflugossa colorata (Nees) Bremek. Vouchers cited: Mackee 20680, MacKee 41911, MacKee 43499 Spontané

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)	native	Zhengyi, Wu/Raven, Peter H./Deyuan, Hong (2013) Forests on mountain slopes; 800-2000 m. Xizang (Cona)

Indian Ocean
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
La Réunion (France) La Réunion Island	La Réunion Island	introduced invasive	U.S. Dept. Agr., Agr. Res. Serv. (2013) Naturalized
La Réunion (France) La Réunion Island	La Réunion Island	introduced invasive	Lavergne, Christophe (2006) Forêts humides de moyenne altitude et de montagne, surtout dans les ravines. Très envahissant
La Réunion (France) La Réunion Island	La Réunion Island	introduced invasive cultivated	Comité français de l'Union Internationale pour la Conservation de la Nature en France (2013) Envahissant
La Réunion (France) La Réunion Island	La Réunion Island	introduced invasive	Meyer, Jean-Yves/Lavergne, Christophe (2004) (p. 337)
Mauritius Mautitius Islands (Mauritius and Rodrigues)	Mauritius Island	introduced invasive	U.S. Dept. Agr., Agr. Res. Serv. (2013) Naturalized
Mauritius Mautitius Islands (Mauritius and Rodrigues)	Mauritius Island	introduced invasive	Meyer, Jean-Yves/Lavergne, Christophe (2004) (pp. 337, 352) Vouchers cited: Herbarium specimens (MAU)

Control:  If you know of control methods for Strobilanthes hamiltoniana, please let us know.