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A study entitled ‘Assessment of diversity in native orchids’ was conducted in the
Department of Floriculture and Landscaping, College of Agriculture, Vellanikkara,
from July 2019 to June 2020. The objective of the study was to assess the diversity
among the native orchid accessions by evaluating their morphological characters. The
morphological characters of twenty three native orchid accessions conserved under the
Department of Floriculture and Landscaping were studied.
Based on the growth habit, five accessions were classified as monopodial orchids
and 18 accessions were classified as sympodial orchids. The accessions viz; Acampe
praemorsa, Aerides crispa, Rhynchostylis retusa, Vanda thwaitesii and Luisia sp. were
grouped under monopodials, and the accessions belonging to genera viz; Dendrobium,
Eria, Pholidota, Bulbophyllum, Flickingeria, Coelogyne, Cymbidium and Oberonia
were grouped under sympodials. The quantitative vegetative characters varied
significantly among the accessions. Among the monopodial accessions, Acampe
praemorsa (VKA/NOR-3) recorded maximum plant height (43.36 cm), internodal
length (2.40 cm), leaf length (23.94 cm), leaf width (2.76 cm) and leaf sheath length
(3.60 cm). In sympodial orchid accessions, plant height recorded was highest for
Dendrobium moschatum (VKA/NOR-37) (75.20 cm). The highest plant spread was
observed in Luisia sp. (VKA/NOR-7) (1571.28 sq.cm) among monopodials, whereas
Dendrobium crumenatum (VKA/NOR-34) (3979.22 sq.cm) was superior in terms of
this parameter among the sympodials. These two species also recorded maximum
number of leaves compared to other accessions (89.20 and 95.80). Among sympodials,
Cymbidium accessions were observed to be superior in terms of the parameter leaf
length, and maximum leaf length was recorded in Cymbidium ensifolium (VKA/NOR-
43) (43.50 cm). Variability was also noted among the accessions with regard to
qualitative vegetative characters viz; leaf shape, leaf orientation, leaf arrangement and
root colour.
Nine native orchid accessions bloomed during the study period were evaluated for
their floral characters. Among them Dendrobium crumenatum (VKA/NOR-34)
exhibited three flowering seasons (April-May, October, Dec-Jan). The accessionPholidota imbricata (VKA/NOR-29) recorded highest spike length as well as rachis
length (49.66 cm and 23.50 cm). The number of florets per spike recorded was
maximum in Rhynchostylis retusa (VKA/NOR-4) (99.33). Largest showy flower
among the accessions was observed in Dendrobium moschatum (VKA/NOR-37) with
maximum flower size of 54.37 sq.cm, highest petal length (3.98 cm), petal width (2.94
cm), petal to petal distance (6.89 cm), length of dorsal sepal (3.49 cm), width of dorsal
sepal (1.63 cm), and length of lateral sepal (3.01 cm). Lip (labellum) is the most
attractive feature of an orchid flower and is found to have variations. The accession
Dendrobium crumenatum (VKA/NOR-34) (2.75 cm) was found to have maximum lip
(labellum) length and Dendrobium moschatum (VKA/NOR-37) (2.28 cm) was found
to have maximum lip (labellum) width. The longevity of spike on plant recorded was
maximum for Dendrobium ovatum (VKA/NOR-60) (12.00 days), and the longevity of
florets on spike recorded was maximum in Acampe praemorsa (VKA/NOR-3) (19.00
days). The pollen viability (%) was found to be more than 90 percentage for all the
accessions flowered and it was noted maximum for Rhynchostylis retusa (VKA/NOR-
4) (98.27 percentage).
Cluster analysis at 75 percentage similarity among the accessions done based on
their quantitative characters resulted in different clusters containing accessions with
similar morphological traits. Among sympodials most of the accessions were grouped
under Cluster A with common characters for plant spread as well as leaf width. With
respect to quantitative floral characters most of the accessions were grouped under
Cluster A and they showed similarity for characters such as number of spikes, flower
size, petal length and width, petal to petal distance, dorsal sepal to lip distance, length
and width of lateral sepal and dorsal sepal, and also length and width of lip and column.
Wide variation was observed in spike orientation, petal shape, petal curvature and
lip shape. The accessions were also noted for the presence of flower fragrance, and it
was recorded in Dendrobium crumenatum (VKA/NOR-34), Dendrobium fimbriatum
(VKA/NOR-27), Dendrobium moschatum (VKA/NOR-37), Acampe praemorsa
(VKA/NOR-3), Rhynchostylis retusa (VKA/NOR-4) and Eria fragrans (VKA/NOR-
25). The floral parts of the accessions also exhibited different sepal, petal, lip and
column colouration.Based on morphological evaluation, superior accessions were identified for
commercial traits and accordingly they were grouped as pot plant types (VKA/NOR-4,
VKA/NOR-39, VKA/NOR-29), fragrant flowered types (VKA/NOR-27, VKA/NOR-
34, VKA/NOR-37, VKA/NOR-4, VKA/NOR-3) accessions with long spike
(VKA/NOR-4, VKA/NOR-29), greater number of florets (VKA/NOR-4, VKA/NOR-
29) and highest longevity (VKA/NOR-29, VKA/NOR-3). Diversity assessment using
cluster analysis has revealed the variability as well as similarity existed among native
orchid accessions on the basis of their morphological characters. The findings are
highly useful for identification of superior accessions which can be utilized for crop
improvement programmes and also for commercial floriculture.