Orchid species diversity: A review of the literature and future research directions

Introduction

A captivating genus of flowering plants, orchids are remarkably diverse and ecologically significant on a global scale. Among monocotyledons, orchids, which are members of the Orchidaceae family, are deemed to be the most highly evolved in terms of floral specialization and diverse shape. With 600-800 genera and 25,000-35,000 species, they are the most highly evolved family of monocotyledons in terms of taxonomy. There is a remarkable variety in the size, shape, and color of orchid blossoms. There is evidence that certain orchid species, such as Vanda roxburghii, Vanda tessellata, Eulophia campestris, Dendrobium nobile, and Orchis latifolia, have therapeutic uses. Although there are many epiphytic orchids, the commercial orchids are both terrestrial and epiphytic. For commercial production, both monopodial (growing on a single stem) and sympodial (growing on multiple stems) are preferred.

Morphology of orchids

The Perennial herbs with simple leaves make up the majority of orchids. While the specialized floral structure is consistent, there is a lot of variation in the vegetative components, with many being terrestrial or epiphytes and a few saprophytes having no leaves. (Tiwari et.al, 2024) [4] Orchid flowers are all carried in inflorescences, which can be branched panicles, simple racemes, or spikes. Orchid blossoms are zygomorphic.

Cultivation

Planting: Orchids are frequently planted in plastic pots, earthern pots, baskets, tree fern blocks, wooden trays, and coconut husks. Lighter media, such as charcoal, coconut husk, and tree fern fiber, are used to grow orchids in hanging pots or baskets. For terrestrial orchids, clay pots work well. Epiphytes are kept in plastic pots.

Potting media: The best potting medium for epiphytic orchids' vegetative growth and flowering is a mixture of equal parts charcoal, brick fragments, and coconut fiber. Sand, soil, and leaf mold in equal amounts. Various amounts of clay soil, bone meal, sawdust, charcoal dust, manure, wood savings, etc. are also utilized to ensure that terrestrial orchids thrive well. (Tiwari and Kumar 2014) [4] .

Manuring and fertilization: Since they are light feeders, orchids need nitrogen throughout the first two-thirds of their life cycle. High amounts of potassium and low levels of phosphate and nitrogen are maintained during the flowering period. Highquality flower production is achieved by applying a concentration of 0.2-0.3% of 30:10:10 (N:P:K) during the vegetative stage and 10:20:20 (N:P:K) during the blooming stage.

Enumerations

Serial

Orchid species Description

Yellow, mildly fragrant flowers that are 1 cm across; sepals and petals are yellow with transverse bands of reddish brown; the lip is white with a hint of purple-red.

Epiphyte on the trunk of a tree

November

2

Acampe rigida (Buch.-Ham. ex Sm.) Lips are white with longitudinal stripes of purplish brown above; flowers are yellow with transverse stripes of purplish brown.

On huge branches or tree trunks, epiphytes grow. June -July 3

Acanthephippium striatum

Creamy white tubular flowers with parallel red veining measure 3.5 to 4.5 cm in diameter.

Growing in damp, shady areas along stream banks and in thick forests. June -July [11] The crimson flowers were 1.6 cm long and heavily speckled.

Epiphytic in secondary evergreen and riverine forests. April 19 Calanthe lyroglossa Rchb.f. Yellow, tiny flowers that become black when dried. terrestrial along riverbanks in moist areas

November-February 20

Calanthe sylvatica (Thouars) Lindl.

Flowers with a purple lip and a delicate pinkish purple color that can occasionally flush orange terrestrial along riverbanks in moist areas.

21

Ceratostylis sabulata A profound, humid, evergreen forest's tree trunk is habitat to epiphytes.

In a wide, humid, evergreen forest, an epiphyte grows on the stumps of trees.

22

Chrysoglossum ornatum Blume

Green flowers with reddish-brown lines, 2 cm across; column white, lip white or yellowish dotted with purple.

Shaded and humid locations in evergreen forests.

August -October 23

Chrysoglossum robinsonii

Flowers are 2 cm across, with green petals and sepals, a white lip, and a yellow column.

Humid and shaded areas in dense woodlands June -July 24 Cleisocentron pallens (Cathcart ex Lindl.)

Pinkish flowers which range from 2.5 to 2.8 cm in dimensions, with pale straw-colored sepals and petals and a pink band in the center

Evergreen woodlands with epiphytic trees on their trunks. June -July

25

Cleisostoma appendiculatum (Lindl.) Benth. & Hook.f. ex B.D.Jacks.

1.5 cm in diameter, with buff sepals and purple longitudinal lines on the petals.

in evergreen forest environments, epiphytic on tree trunks.

August-October 26

Cleisostoma filiforme (Lindl.) Garay Sepals and petals are yellowish green with reddish brown stripes, the lip is white with a purple-red midlobe, and the column is yellow. The flowers are around 1.3 cm across.

Epiphytic on host evergreen tree in dense forests

27

Cleisostoma linearilobatum (Seidenf. & Smitinand) Garay

Little yellow flowers with a pinkish-white lip that become brown. [7] Lip cream-colored, 4-5 cm across, mildly fragrant, with pale yellow to cream-yellow sepals and petals with a wide maroon-brown stripe in the center.

Epiphytic host specific April -May;

36 Cymbidium bicolor Lindl.

Flowers are 3-4 cm in diameter, with yellow sepals and petals and a longitudinal stripe of purplish red in the center. The lip color is cream-yellow.

In a deep, humid, evergreen forest, an epiphyte grows on tree trunks.

37

Cymbidium dayanum

Rchb.f. Sepals and petals are white with a central maroon stripe, and the lip is maroon with a hint of white at the base. The flowers are 4 to 5 cm across.

In a dense, humid, evergreen forest, an epiphytic grows on host tree. June -July. Sepals and petals are golden yellow, and the lip is golden yellow, either with or without a maroon blotch.

The flowers are 4-5 cm across.

In humid evergreen trees as well as mixed deciduous forests, epiphytes

March -May 44

Dendrobium lituiflorum

Flowers are 4-5 cm across, with a deep purple spot encircled by a white circle on the pale purple inner surface of the lip.

On tree trunks in open woodlands, epiphytic

Dendrobium moschatum

A deep yellow disk with a pale purplish brown patch on either side, the flower is orange-yellow and 5-7 cm wide.

Epiphytes on host tree in open greenery forest.

April -June 46

Flowers are 5 to 7 cm across, with a deep purple blotch in the center and a purple lip at the tip and a white merging with purple at the apex.

Epiphyte is found in lowland, damp evergreen forests.

April -May 47

Dendrobium stuposum

Little white flowers with a drab yellow patch on the edge.

Dendrobium transparens

Wall. ex Lindl. (Hartati, S 2022) [10] Flowers are 4-5 cm across, with a huge purple patch on the disc and a white lip with purple shades on the sepals and petals.

Epiphyte Pinkish-white, pubescent, buff flowers with darker stripes.

In forests of deciduous and forests with evergreens, epiphytes are found.

April-August 62

Eria pumila

Lindl. Pink-flushed white flowers.

In humid evergreen and mixed deciduous forests, epiphytes are found. January-March.

63

Eria tomentosa (J.Koenig) Hook.f. (Choden, K 2021) [8] Flowers are orange-yellow and about 1.5 cm wide.

In forests of deciduous and forests with evergreens, host specific epiphytes are found.

64

Eulophia hormusjii Duthie

Brownish colour flowers, 3-4 cm in diameter. Terrestrial, growing on loose, bare soil. August-December.

65

Flickingeria fugax (Rchb.f.) Seidenf. White flowers that are fugacious and 3-3.5 cm across. Epiphytes in mixed deciduous and wet evergreen forests.

March -October 66

Gastrochilus calceolaris (Buch-Ham. ex Sm.) D.Don

The sepals and petals are yellow with reddish brown markings, the lip is white with purple-red markings, and the flowers open widely.

Epiphyte in mixed deciduous and wet evergreen forests.

67

Gastrochilus dasypogon (Sm.) Kuntze Yellow flowers that are 1.5-2 cm wide and with brownish-purple lines Epiphyte in mixed deciduous and moist evergreen forests

October -November 68

Gastrochilus inconspicuous (Hook.f.) Kuntze Flowers are 0.5 cm across and could vary between white or yellowish-green.

Epiphyte in mixed deciduous along with humid evergreen forests June -July.

69

Geodorum densiflorum (Lam.) Schltr.

White to pinkish flowers with crimson-purple venation and streaks on the lip and a yellow callus in the center.

In grassland and evergreen forests, terrestrial June -July.

70

Goodyera procera (Ker Gawl.) Hook.

Fragrant, weakly opening flowers with a pale green tint and a white tint terrestrial, both on rock in a stream and on the bank of a small stream, as well as in an evergreen forests. Sepals and petals are white with a hint of pink or purplish, and the lip is deep purple-red. The flowers are 5-10 cm across.

April

In mixed deciduous forests, epiphytes can be found on scattered wayside trees.

April -May 85

Phaius mishmensis (Lindl. & Paxton) Rchb.f. White, greenish yellow, or pinkish purple flowers, 4-5 cm across Terrestrial, in the middle of a thick, humid evergreen forest, along a tiny flow.

86

Phaius tankervilleae (Banks) Blume

Sepals and petals are white on the outside and reddish brown or brown on the inside, while the lip is white at the base and pink or red-pink at the entrance, with white stripes on the inside. Flowers are 7 to 12 cm across.

93

Pomatocalpa undulatum (Lindl.) J.J.Sm.

Purple-blotched yellow flowers, 8 mm across, with a purple-blotched lip.

In the humid, tropical evergreen forest, epiphytes March-May.

94

Pteroceras suaveolens (Roxb.) Holttum About 1.5 cm across, the flower is yellow with brownish lines and has a dark purple lip tip.

The damp evergreen tropical forest's epiphyte. June -July 95 Rhynchostylis retusa (L.) Blume (Kumar,S 1997) Sepals and petals are white with pink or pastel purple spots, the apex is white, and the flowers are 1.7-2.3 cm across.

In (Ray, H 2022) [12] Flowers are 1 cm wide and delicate white. In a humid forest, epiphytes grow on tree trunks.

107

Tropidia curculigoides Lindl. Greenish white, 1.5 cm long flowers Both terrestrial and evergreen montane forests are densely moist.

September

January-March

Conclusion

The orchid family is at high risk of extinction due to a number of factors, including the frequent and quick destruction of natural habitat through deforestation, upper layer soil erosion, overgrazing, herbicide effects that harm many saprophytic and terrestrial species, the expansion of agricultural lands through forest clearing, development plans, rapid urbanization, ignorance, and, lastly, indiscriminate collection for the floral industry, which aggravates the populations of the species in the domains. Plant distributions must be recorded for conservation purposes. A good dwelling for orchids is provided by the ecological conditions, which include tropical and subtropical regions, welldrained soil, and shaded, forested areas. It is advised to conduct additional research on the population dynamics and habitat preferences of orchids in order to better understand their occurrence and create specific conservation plans.

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