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|Vol. 13(2), pp. 11-16||The McAllen International Orchid Society Journal||February 2012|
Effective Publication Date : 1-Feb-2012
1 Department of Botany, St. Joseph's College, P.O. North Point, District Darjeeling, W. B., India 734104
2 Taxonomy & Ethnobiology Research Laboratory, Cluny Women's College, P.O. Kalimpong, District Darjeeling, W. B., India 734301
3 Daisa Bordoloi Nagar, Talap, Tinsukia, Assam, India 786156
4 Darjeeling Krishi Vigyan Kendra, Uttar Banga Krishi Viswavidyalaya, P.O. Kalimpong, District Darjeeling, W. B., India 734301
* Corresponding author E-mail: email@example.com
This paper deals with the intraspecific floral morphological variation in the population of Eria amica Rchb. f. (Orchidaceae) in Darjeeling Himalaya of India. Floral morphological variations were observed in Eria amica Rchb. f. where flower size were smaller with distinct-colour variation due to the presence of light purple coloured longitudinal lamellae on the disc, light yellow apical lobe; lateral lobes light pink, ventral side of mentum base is light pale colour instead of distinct dark coloured longitudinal lamellae on the disc; distinct yellow apical lobe, lateral lobes dark pink and dark coloured ventral side of mentum base. Some biologists consider flower colour variation as new species, variety or forma, but in this case it is merely due to environmental pressures on the natural population. The current ecological status is sparse because of habitat destruction and over collection and immediate conservation activities are needed to save it from being exterminated in its present habitat.
Orchidaceae, Eria amica, intraspecific floral morphological variation, Current status, Darjeeling Himalaya, India.
The genus Eria was established in 1825 by John Lindley in the Botanical Register. Dressler (1993) accords the genus about 500 species, widespread in tropical Asia, extending east to New Guinea, Australia and the Pacific Islands. Seidenfaden, in 1982 received the Thai species, and a fuller synonymy of the widespread species can be found there. John Day received the type specimen from his nephews Williamson and C. Williamson in Assam and illustrated the species in his sketchbook (Vol. 11, t.63) which is now at Kew Garden (Pearce and Cribb, 2002). Another good illustration of this species can be found in Summerhayes in 1936 who also discussed the taxonomy of this genus.
Eria amica is found growing as epiphytically mostly on Schima wallichii trunks and branches at an elevation of 730-900m. It flowers during March-May. It is generally distributed in the Tropical Asia, New Guinea, Australia, Nepal, Myanmar, China, Thailand, Vietnam, Pacific Islands, North-Eastern India, Sikkim, Darjeeling and Bhutan. Locally it is found in Kumsi forest area of Kalimpong where the variation was observed. The current ecological status in Darjeeling Himalaya was studied following the method of Raunukiaer's Ecological Statistics (Raunkiaer, 1934) at different locations of Darjeeling hills. The result revealed that Eria amica is also facing threats similar to other plants and we have proposed to keep it as "sparse" and in the possible-rare category in Darjeeling Himalaya.
Plant epiphytic, 20cm tall. Pseudobulbs erect-cylindric, sheathed at base, 9-14x1.2-1.3cm. Leaves 3, arising from pseudobulb apex, linear-lanceolate to oblong-lanceolate, acute, tapered to petiolate base, 1-1.5cm; petiole grooved, 1.4-2x0.1-0.2cm long. Inflorescence 1, arising from axils of leaf-sheaths, suberect, laxly 11 flowered; peduncle slender, 1.6cm long; rachis slender, pubescent, 5.4cm long; floral bracts oblong-lanceolate, subacute, reflexed, 0.7-1x0.5-0.6cm long. Flowers 1.3mm across; sepals and petals buff-yellow to greenish-yellow with red veins, lip pinkish light yellow apex and purple lateral lobes and lamellae; pedicel pubescent, 1.4-2x0.1-0.2cm long. Sepals subsimilar; dorsal sepal 0.9-1x0.4cm, lanceolate, acute; lateral sepals lanceolate, oblique, connate at base to form a mentum/foot with the column; mentum pubescent externally. Petals linear-lanceolate, acute, 0.8-0.9x0.3-0.4cm long. Labellum 3-lobed, shortly clawed, 0.5-0.7x0.3-0.5cm; lateral lobes erect, triangular, apex rounded, pale yellow with clavate purple blotch, obtuse to subacute; apical lobe reniform, decurved; 2-lobed, rounded, light yellow; the disc with 3 pink lamellae, the lateral lamellae are ridges, middle one extending and meet all the 3 lamellae at the base of apical lobe; Column incurved, 3-4mm long; mentum 0.3x0.2cm long, base of inner potion of mentum light pink patches. Anther 1-1.2mm, ovate, light yellow. Pollinia 8, 0.5x0.3mm oval, yellow.
In the present investigation, the observations were made on intraspecific variation in floral morphology of Eria amica Rchb. f. a species of Orchidaceae which could not be traced anywhere in the literature cited by earlier workers. Thus, this report could be first of its kind where such floral morphological variations were observed.
In 2010-11, during periodic field surveys of Neora Valley, Singhalila National Park, Lava range of forest, the surrounding hillocks of Kalimpong town and the far flung villages, some unusual phenotypic variations were observed in plants of Eria amica in the Kumsi forest area and Durpin hill of the Kalimpong Block- I of Darjeeling district. The authors collected four specimens of Eria amica from a 350 m2 area without uprooting and disturbing the plants in the habitat. These collected specimens were studied in the laboratory to confirm not only identification, but to investigate reasons why variation exists within the same species. This was done following the classification given by Hooker (1888-1890), King and Pantling (1898); Duthie (1906); Pradhan (1976, 1979), Pearce and Cribb (2002), and Lucksom (2007). Corroboration also came from the herbarium of Department of Botany, St. Joseph's College, North Point, Darjeeling and Taxonomy and Ethnobiology Research Laboratory of Cluny Women's College, Kalimpong.
As detailed observations were made, the deviation in the colour of flower parts was recorded and comparative studies were carried out with normal flowers. The ecological status of Eria amica was studied following the method given by Raunkiaer (1934), and field projects were carried out to study the species habitat. For quantification, representative plots of 10m x 10m were laid down with sub plots of 5m x 5m diagonally. In each major plot for regeneration status of frequency method for quantification studies were carried out to arrive at the current status of this species from study area. To determine the current status of Eria amica, authors used quadrate sampling methods 5m x 5m in the habitat rich sampled field.
The observations made on the variation in floral morphology and in colour of lamellae on disc are presented in Table 1.
|Plant||Normal Species||Variant Species|
|Stem||9-15 x 1-1.5||9-14 x 1.5-2.1|
|Leaves||2-4, 10-17 x 1.8-2.9||3, 12-14.5 x 1.5-2.1|
|Inflorescence||1-4, 5-10 long, 9-13 fls, peduncle 2.3, rachis 7.7||1, 7 long, 11 fls, peduncle 1.6, rachis 5.4|
|Flower||1.4-1.6 NS dull ylo w/reddish-purple nerves, 3 dark longitudinal lamellae middle of disc, meeting at base of apical lobe; column 0.3-0.4 x 0.3 white; anther 0.11-0.12 x 0.12-0.13 ovate, lgt ylo; pollinia 8, ylo, oval 0.05 x 0.03.||1.1-1.3 NS, lgt ylo w/reddish purple nerve; 3 purple lamellae on lamina meeting at base of apical lobe of lip; column 0.3 x 0.2; anther 0.11 x 0.12; pollinia 8, ylo, 0.03 x 0.02|
|Dorsal Sepal||1-1.1 x 0.4-0.5, dorsal sepal-lateral sepal 1.4 across||0.8-1 x 0.4, dorsal sepal-lateral sepal 1.3 across|
|Lateral Sepals||0.9-1 x 0.4-0.5, triangular, obtuse, 5-nerved, dorsally.||0.8-0.9 x 0.5-0.6cm. lateral sepal-lateral sepal-1.4cm across|
|Petals||0.9 x 0.3-0.4cm, Lateral petal to lateral petal-0.8cm across.||0.8-0.9 x 0.3-0.4cm. Lateral petal-lateral petal-0.6cm across.|
|Labellum||0.8-0.9 x 0.4-0.6cm long, 0.8 expanded, blackened at claw, lamina distinctly 3-lobed, lateral lobes erect, 0.5-0.6 x 0.4-0.5, oblong, apex rounded, dk-purple blotch; apical lobe 0.4-0.6cm; reniform, decurved; mentum short, basal portion of mentum abaxially a black blotch; disc with 3 dk purple lamellae 0.6-0.7 meeting at base of apical lobe.||0.5-0.7 x 0.3-0.5, 0.6 expanded, purple at claw, lamina distinctly 3-lobed, lateral lobes erect, 0.5 x 0.3; & 0.7 spread; oblong, light purple, apical lobe 0.3-0.5; reniform, decurved; disc with 3 purple lamellae 0.6 meeting at base of apical lobe; run at claw with middle lamella shallow. Mentum abaxially a light pale triangular blotch.|
Fig. 1. Intraspecific variations within the population of Eria amica Rchb. f.
Clearly, the species studied varied distinctly in most of the studied plant characters. The comparison is presented between normal plants and the ones in which variation occurred. The major floral parts varied within the species in both morphology and colour. The intraspecific floral morphological variation is shown (Fig. 1) where B, B1, B2 and B3 are floral parts taken from plant showing variation and have slightly smaller flower size and distinct different coloration compared to the normal. These differences are expressed as the presence of light purple coloured longitudinal lamellae on the disc; a light yellow coloured apical lobe; and the lateral lobes light pink. The abaxial aspect of the mentum base is a light pale colour instead of exhibiting a distinct dark coloured longitudinal lamellae on the disc. There is a distinct yellow apical lobe, lateral lobes dark pink and dark coloured ventral side of mentum base of A, A1, A2 and A3 of type species of Eria amica Rchb. f.
After critical observations, literature consultation, and discussion, the taxonomic identity of this species has been finalized, and we conclude that although all are of the same species, intraspecific floral morphological as well as colour variation exists within natural populations of this species. In similar studies during a field survey of various other parts of Darjeeling Himalaya other populations did not display any such variation in nature.
Eria amica is found growing as an epiphyte mostly on Schima wallichii trunks and branches at elevations of 730-900m. This species flowers during March to May. It is generally distributed in Tropical Asia, New Guinea, Australia, Nepal, Myanmar, China, Thailand, Vietnam, Pacific Islands, North-Eastern India, Sikkim, Darjeeling and Bhutan. Locally it is found in Kumsi forest area of Kalimpong where the variations were observed. The current ecological status in Darjeeling Himalaya was studied following the method of Raunukiaer's Ecological Statistics (Raunkiaer, 1934) at different locations of Darjeeling hills. The result revealed that Eria amica is also facing the threat like other plants and we propose to keep it in the categorized as sparse and possibly rare in Darjeeling Himalaya.
Colour of a flower is not a major criteria in plant taxonomy despite some biologists considering it as a trend and using it to distinguish such new species, varieties or formas. Here, colour has not been considered as a new species, a new variety nor as a forma, but as an intraspecific variation resulting from environmental effects on the natural population. Populations are sparse because of habitat destruction, and immediate attention should be given to conservation measures.
Wherever, orchids species exist in nature, the felling of host plants should be cleared only after examination of such plants by conservationists/botanists. The random felling of trees and the general deforestation associated with commercial plantations should be stopped immediately!
The authors are thankful to the University Grants Commission, New Delhi for awarding Rajiv Gandhi National Fellowship (Junior Research Fellowship) for Ph. D. in Botany on the Research Project titled "Studies on the Orchid Flora of Darjeeling Himalaya".
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