Eulophia obtusa (Lindl.) Hook.f.

Sourav, M.S.H. et al. 2017. Eulophia obtusa (Orchidaceae: Epidendroideae: Cymbideae) an addition to the flora of Bangladesh, with notes on its ecology and conservation status. Kew Bulletin 72:19. DOI 10.1007/S12225-017-9689-2

Morphology General Habit

Terrestrial, seasonally deciduous herb, bearing under­ground corms

Vegetative Multiplication Corms

Corm white, dome-shaped, 2.5 - 3.1 cm wide and 3.3 - 5.5 cm high, lying 10 - 20 cm below ground, bearing vermiform, white roots

Morphology General Shoots

Shoots 1 - 5­leaved, usually bifoliate, basal part formed by sheaths enveloping the base of the inflorescence as well as the leaf-bases

Morphology Leaves

Leaves appearing with the inflorescence, grass-like, 35 - 50 cm long, 0.15 - 0.5 cm wide, linear, slightly plicate, apex acuminate, midrib prominent, sheathing at base

Morphology Reproductive morphology Inflorescences

Inflorescence erect, 40 - 60 cm tall; peduncle terete with a few distant, c. 5 cm long, linear- triangular, sterile bracts; rachis up to c. 10 cm long, bearing 4 - 12 flowers usually opening simultaneously and more or less evenly spaced

Morphology Reproductive morphology Flowers

Flower 3 - 4 cm diam.; sepals and petals white, lip white tinged pink, with numerous deeper purplish pink, branching veins, zone surrounding the mouth of the spur light green; calli white, green in the basal part of the lip; spur green; column creamy white, apex red-purple, anther yellowish tinged green, with faint purple markings

Morphology Reproductive morphology Inflorescences Bracts

Floral bracts c. 1.4 cm long, lanceolate, acuminate, much shorter than the combined length of pedicel and ovary

Morphology Reproductive morphology Flowers Pedicel

Pedicel with ovary c. 24 mm long, curved, glabrous, terete, ovary ribbed

Morphology Reproductive morphology Flowers Calyx

Dorsal sepal c. 2.0 x 0.5 cm, oblong-lanceolate, acute, 7-nerved; lateral sepals similar, c. 1.8 x 0.5 cm

Morphology Reproductive morphology Flowers Corolla

Lip 2.1 x 1.7 cm when flattened, at right angles to the column, 3-lobed; lateral lobes basal, erect, c. 5 x 4 mm, semi-elliptic, rounded; midlobe c. 1.7 x 1.3 cm, elliptic, almost truncate, margins undulate; callus complex, consisting of 3 - 4 short, transverse ribs on either side of the mouth of the spur, and 5 longitudinal ribs of unequal size and height occupying most of the median part of the midlobe; veins thickened; spur c. 6.7 mm long, conico-cylindrical, obtuse, curved forward and appressed on the abaxial surface of the labellum Petals 1.8 x 0.6 cm, oblong- lanceolate, obtuse

Morphology Reproductive morphology Flowers Column

Column 8 mm long, with short foot

Morphology Reproductive morphology Fruits

Fruit not seen (Description based on material from Bangladesh only)

Distribution

Northwest India (Uttarakhand, Uttar Pradesh, ?Assam, ?Chhattisgarh), ?Nepal, Bangladesh.

Ecology

The only known site of Eulophia obtusa in Bangladesh is situated in the high Barind tract, one of the major agro-ecological regions comprising about 79% of Godagari upazila. The area lies at about 15 m above sea level, and is not normally flooded, although the grassland in which the orchid occurred was usually water-logged during the peak of the rainy season. The vegetation is composed of grasses like Imperata cylindrica and Saccharum spontaneum as well as herbs and shrubs, including Amorphophallus margaritifer, A. paeoniifolius, Boerhavia diffusa, Chrozophora rottleri, Colocasia esculenta, Commelina benghalensis, Croton bonplandianus, Cyanotis cristata, Cyperus sp., Digera muricata, Euphorbia hirta, Ficus hispida, Kyllinga microcephala, Leucas lavandulifolia, Lippia alba, Parthenium hysterophorus, Phyllanthus virgatus, Solanum villosum, Uraria picta, and others. In North India, Eulophia obtusa has been found in freshwater swamps (Deva & Naithani1986). The elevations have not been recorded for the collections we have seen, but they are probably all from below 200 m asl.

Phenology

Flowering: June - July; fruiting: not seen, but local informants stated that they had seen the plants in fruit.

Note

An unpublished painting from 9 July 1900 in the Icones collection of Kew by H. Hormusji of an orchid collected in the Raipur District of Central India (Chhattisgarh) and grown by J. Martin represents a taxon that is strikingly similar to the Bangladesh form of E. obtusa in colour, except that it lacks the green tinge in the basal part of the lip. It differs in the much simpler callus structure: instead of a series of small transverse calli along the mouth of the spur there are just two large, wing-shaped, undulate calli, which are connected to three (not five) lamellae on the mid­lobe. Since the artist also drew the column, anther and pollinarium in great detail, we do not think that the simpler callus structure is due to a superficial and inaccurate representation. If this painting represents a form of E. obtusa, then it is evidence for a considerable range extension towards the South. The painting had been annotated as "" Eulophia n. sp."" by R. A. Rolfe. It should be noted that Duthie (1906) claimed that the collecting locality of Eulophia obtusa as cited by Lindley refers to that of a specimen of E. fl ava (Lindl.) Hook. f. There are no locality data on the type sheet of E. obtusa, and we do not know on what grounds Duthie made his claim.