Distribution of six little known plant species from Arunachal Pradesh , India

Arunachal Pradesh being a part of the HimalayaEast Himalaya biogeographic zone (Rodgers et al. 2000) is also the confluence point of three biogeographic realms, namely, the Afro-tropical, the Indo-Malayan and the Indo-Chinese (Takhtajan 1969). It harbours a unique composition of different plant communities, influenced by various factors including rainfall, temperature, humidity and altitude (Biswas 1966). The biodiversity of Arunachal Pradesh is supported by a wide range of endemic species and various fragile ecosystems. More than 82% of the geographical area of the state is covered with forests, which are the custodians of c. 29% flowering plants of India (Hajra & Mudgal 1997). During the recent floristic survey conducted in the Kurung Kumey District of Arunachal Pradesh, six interesting species were collected which were known only from the type locality. The present collection of these species from areas other than the type localities confirms that they may have a wider distribution in this region. Out of the six species, Dalbergia thomsonii

Ecology: Found in gregarious patches on forest floors, moist and damp grounds of primary forests, 800-1500 m.
Notes: After type, this species was first collected by I.H.Burkill from the Abor Hills of Arunachal Pradesh on 24.xi.1911 and was known only from its type locality till it was recollected from Kameng District of Arunachal Pradesh on 24.iii.1957by G. Panigrahi.While exploring the Kurung Kumey District, the species was again collected and a good population was found scattered along the primary forest floors.
Notes: Dalbergia thomsonii Benth. is endemic to Assam, Meghalaya and Tripura (Kumar & Sane 2003).This species was first collected from Arunachal Pradesh by G.D. Pal from Yazali of Lower Subansiri District and wrongly identified as Dalbergia assamica Benth.
Notes: This species was recently described by Sabu et al. from Lohit District of Arunachal Pradesh (Kress et al. 2010) and was known only from the type locality.While surveying the Kurung Kumey District, the species was collected by one of us (SSD) from a single locality where c. 150 adult plants were growing.The occurrence of this species in Kurung Kumey District shows that the species might have a wider distribution in the state.It is interesting to note that the specimens collected from Kurung Kumey District differ from the protologue by its complete nature of glabrousness.Studies on the herbarium specimens as well as live plants in the field, could not confirm the hairy nature of leaf ligules, pubescent nature of the leaf lamina with silvery hair, twisting condition of the leaf apex and pubescent nature of the floral bract as mentioned in the protologue.Rhizomatous herbs, 60-80 cm high.Leaves oblong-lanceolate or elliptic-lanceolate, 20-35 × 5-7 cm, glabrous above, glaucous beneath, base narrowed to a leaf sheath, margins entire, apex finely acuminate; leaf sheaths 5-11 cm long, drying brown, whitish inside; ligules bilobed.Inflorescence terminal, usually on a reflexed peduncle, erect, 7-9 x 3-8 cm, glabrous; involucral bracts deep red, 3-4 x 0.7-1 cm, acuminate at apex; floral bracts overlapping, closely clasping to each other, 2-3 x 0.8-1.3cm, conspicuously veined.Flowers white, 1-3 per bract.Calyx tubular.Corolla lobes linear-lanceolate; lobes conspicuous.Staminodes reddish, ovate, with a reflexed labellum of 2-2.5 cm long; fertile stamens whitish, light orange outside arched at base, oblong.Ovary trilobed.
Notes: This species was recently described from Barail Wildlife Sanctuary, Cachar District, Assam by Dey et al. and was known only from two locations in the sanctuary (Kress et al. 2010).The present collection from the Kane Wildlife Sanctuary (West Siang District) establishes northern extension of the species and its first record for the state of Arunachal Pradesh.During the survey, only 10-15 plants were observed in the field.Scandent shrubs.Stems up to 20m long, ascending.Leaf sheaths tomentose, densely spiny; spines straight, arranged in wavy manner, oblique at mouth.Petioles very short, often clasping to stem.Leaves 2-3.5 m long; pinnae linear-lanceolate, narrowed to a long filiform cirrate apex; rachis flattened, tomentose, lower part sometimes spiny, upper part heavily armed with recurved spines (grapnels).Male rachis zigzag; bracteoles inflorescences axillary; peduncles drooping, covered with densely overlapping floral bracts broadly ovate or rhombic, 4-5 cm long, apex acuminate; calyx tubular, finely tomentose outside, apex acuminate.Fruits globose, spherical, reddishbrown on maturity.
Notes: This species is distributed from Nepal to China (Yunnan).In India it was known to occur in Sikkim.The present collection from Kurung Kumey District forms the basis for the first report of its distribution in Arunachal Pradesh.Vegetatively, the species is easily confused with the scandent species of Calamus in wild, but can be differentiated by the presence of sharp spines on wavy lamellae, long filiform leaf tips, drooping inflorescence and rachilla often hidden by broad bracts.Traditionally the pith of this species is used as fodder and the stem fiber is used for making houses and baskets by the Nishi tribe.Herbs.Stems up to 85cm high, puberulous or glabrous.Leaves lanceolate, 11-17 x 1-5 cm, upper surface papillose-hispid, hispid only on veins beneath, finely acuminate at apex, hispid-ciliate at margins, narrowed to very short petiole-like base; sheaths widely cylindric, 2.2-3 cm long; upper leaves almost overlapping.Inflorescence 5-17.5 cm long, densely glandular-pubescent, terminal; bracteoles leaving scars; flowers borne near ends of branches; pedicels 1-1.5 cm long.Flowers pale mauve to bright blue.