Hemigraphis pacifica Hosok., Trans. Nat. Hist. Soc.

Hemigraphis pacifica Hosok., Trans. Nat. Hist. Soc. View in CoL Formosa 25: 127. 1935. After 1935. Type: MELANESIA, Palau Islands , T. Hosokawa 7400 (holo, TAI) Fig. 1 View Fig

Herbs up to 20 cm tall. Stems short, erect, with shallow ridges, densely covered with multicellular trichomes. Leaves basal, opposite, isophyllous; lamina oblong-ovate or elliptic, 1–6 × 0.6–3.5 cm, adaxially dark green, sparsely pubescent, ventrally light pink, densely pubescent with multicellular trichomes especially along the midrib and lateral veins, margins sub-entire to repand or shallowly crenate, apex obtuse or obtusely acuminate, base subcordate; lateral veins 3–7 pairs, raised beneath; petioles 0.5–2.6 cm long, pubescent. Spikes terminal on main stems and from axils of upper leaves, elongating at maturity; peduncles 2–7 cm long, pubescent; bracts oblanceolate to elliptic, foliaceous, 1.3–2.7 × 0.6–1 cm, pubescent, margins entire, persistent. Calyx 5–lobed, 6.5–7.7 mm long, pubescent; lobes linear-lanceolate, 3.4–4.6 × 0.3– 0.5 mm, divided to the middle, margins ciliate. Corolla slightly 2-lipped, 1.1–1.2 cm long, white or pale violet with darker veins, glabrous; tube funnel-shaped, slightly ventricose, 8.8–9.1 mm long, base 1.1–1.3 mm in diam., mouth 3.5–4.1 mm wide; lobes sub-orbicular, 2.1–2.8 mm in diam. Stamens 4, included, didynamous; filaments united at base, pubescent, shorter pair with 0.5–0.8 mm free part, longer pair with 2.2–2.5 mm free part; anthers oblong, 1.2–1.5 × 0.4-0.5 mm, 2-thecous, sub-basifixed. Ovary oblong, c. 2.8 mm long; style filiform, c. 5.7 mm long, sparsely pubescent. Capsules oblong, 8–9 mm long, 1.4–1.5 mm in diam., pubescent at apex. Seeds flat, ovate-orbicular in outline, 0.9–1.1 × 0.8–0.9 mm, apex acute.

Flowering & fruiting: Flowering from June to September and fruiting from July to December.

Habitat: The plants grow on grassy hill slopes at an elevation of c. 180 m.

Distribution: Taiwan, Japan (Ryukyu Islands), Singapore, Indonesia (Borneo, Seram, Sulawesi, Java, Moluccas, Talaud Islands, Irian Jaya), Philippines ( Bohol, Guimaras Island, Leyte, Luzon and Samar), northern Australia, Melanesia ( Palau Islands, Marshall Islands and Solomon Islands), New Caledonia ( Loyalty Islands), Papua New Guinea (Bismarck Islands). Possibly escaped from cultivation and naturalized in India, Myanmar, Thailand, Laos, Vietnam, Malaysia, Sri Lanka, La Réunion, Hawaii, French Polynesia, and other parts of world ( Fig. 2 View Fig ).

Specimen examined: INDIA, Arunachal Pradesh, West Kameng district, Tippi , N 27 ̊02'04.58'', E 92 ̊36'22.93'', 06.07.2019, J . Sarma s.n. ( HBARC [ HBARC00006506 ]) .

Notes: Strobilanthes reptans shows close affinity with S. hirta (Vahl) Blume [= Hemigraphis hirta (Vahl) T.Anderson ]. However, the latter is clearly distinct by its prostrate habit, woolly pubescent texture (whole plant densely covered with long white hairs), smaller leaves (up to 2.5 cm long), sessile and compact inflorescences ( Wood, 2001). Whereas, in S. reptans the stem is short and erect, plants not woolly, comparatively larger leaves (up to 6 cm long), inflorescence lax, usually borne on long peduncles, elongating at maturity.

It is worthwhile to mention here that S. reptans is an invasive weed in tropical Indo-Pacific Islands (Meyer & Lavergne, 2004). It has also apparently escaped from cultivation and has naturalized in Malaysia, Vietnam, Thailand and Laos, and countries neighboring India, i.e. Myanmar, and in Sri Lanka. The corridor of naturalization seems to represent an expansion of the natural distribution range Northeast towards India ( Fig. 2 View Fig ). As such, it is likely that the occurrence in India is also the result of a recent naturalization rather than representing a disjunct, natural distribution of the species. However, in India no invasive growth was observed at the site of occurrence or during the cultivation of the plant at the Forest nursery in Tezpur, Assam. Also, the species is restricted to a single locality and the area of occupancy is estimated to be less than 1 sq. km. Therefore, in the current scenario no action needs to be taken to control its spread. As the plant is a little-known ornamental, no history of its cultivation in India could be traced.There is evidence for escape and naturalization as the report here indicates because the plant was encountered in a semi-disturbed area. Hence, further investigation and monitoring of its population is recommended.