Department of Botany, University of Calicut, Kerala -673 635, India Email: email@example.com
(Received 5 January 2009, Accepted 25 March 2009)
Leucas specimen with unique characters and deserve the status of a species is located in the Herbarium of Cambridge University (CGE). This specimen was collected from Simla, Himalaya, where no endemic Leucas species has been found out so far. Collection of more specimens is required to name it.
Key words: Lamiaceae, Leucas, Simla - Himalaya.
Leucas R. Br. is a genus of 100-106 species, found in Southern and tropical east Africa, Southern Asia (Arabia to China, especially in India), Australia (Queensland) and to the Pacific Islands. Only one species (L. martinicensis) the indigenous plant of Martinica, West Indies is found in South America. According to Ryding (1998), Leucas is originated in north east tropical Africa and to have migrated from this area over Arabia to Indian sub continent. Morphological features of African and Asian species are different and they are included in different infrageneric sections.m Almost all the Asian species are found in India and majority are Indian endemics. Species density and endemic diversity is more towards the southern Peninsula. Towards the Himalayan and north eastern regions, the diversity decreases. Eastern Himalayan diversity consists of four Leucas species (Hara, 1966), but no endemics are reported. As a part of the overall revision of the Leucas, the author has examined hundreds of herbarium sheets from various herbaria. One specimen observed in the Herbarium of Cambridge University, London (CGE) is unique with many characters. From the label (Fig. 1), it is clear that the specimen was collected from Simla, Himalaya, by Dr. Graham (No. 86) for Lady Delhousie. It must be understood that this specimen came from European stations in Simla region and sources on the history recorded that this area was under Lord Delhousie's rule during 1846-1856. With this clue the time of collection of this specimen can be assumed to be almost before one and half century.
Observation of characters indicate that this specimen share some of the general characters of Leucas section. Astrodon, but differ due to a unique set of character combination. This specimen is truly distinct from all the hitherto described species and deserves the status of a species under this section.
Since a second specimen of this plant is not available in any other herbaria, the author is not in a position to comment much on this plant. Moreover, occurrence of this plant elsewhere is under question, it is not attempted here to name this plant based on a single collection. However, photograph of this plant (taken by the author with permission from the unsorted herbarium bundles of Cambridge University Herbarium, London) is given here with description of available characters. The author hopes that this paper will be of much help to the plant collectors of this area to collect this plant for further studies and to name it.
Branches quadrangular, grooved, pubescent, tender stem villous; internodes 3-6 cm. Leaves petiolate; petiole 1.5-2.5 cm long; blade ovate, thin, 4-5.5 x 3.5-4.5 cm, hispid, upper side glandular punctuate, tip acute to obtuse, margin crenate with 20-25 teeth, base cordate. Inflorescence terminal, 1-2 whorls, many flowered. Bracteoles recurved below the whorls and form an involucre, narrowly ovate, foliaceous with distinct mid rib, lateral veins 2-3, hispid, margin ciliate, hairs 1-1.5mm. Pedicel short. Calyx tubular, 8-9 mm long, outside upper half shortly hispid, veins ribbed, lower half almost glabrous, inside glabrous, mouth not oblique, provided with a ring of veins, not ciliate; teeth 10, almost equal sized, stellately spreading, subulate, 2-2.5 mm long, hispid, hairs 1-1.2 mm. Corolla upper lobe hooded, margin ciliate. Anthers divaricate, twice longer than broad.
I am grateful to Dr. Philip Mathew, Professor Department of Botany, University of Calicut, Kerala for various helps and the International Association of Plant Taxonomy, Vienna for the Research Grant support. I thank all the Directors and Curators of different herbaria (B, BLAT, BM, BP, BR, C, CAL, CALI, CANB, CGE, E, FRI, G, K, KFRI, LE, LINN, LIV, M, MH, P, SKU, TBGT, W, WELT) for giving permission to study the herbarium specimens or providing specimens on loan. Hospitality provided by the authorities of different herbaria particularly that of Cambridge University, and Royal Botanical Gardens Kew, London U. K during my visit there is thankfully acknowledged.
Hara, H. 1966. Flora of Eastern Himalaya, University of Tokyo, Japan.
Ryding, O. 1998. Phylogeny of the Leucas Group (Lamiaceae); Syst. Bot. 23: 235-247