An inventory of new orchid (Orchidaceae) records from Kozhikode, Kerala, India

: Orchidaceae is one of the largest families in the plant kingdom. It has high diversity within the tropical and subtropical parts of the world, and is considered as a characteristic feature to measure forest richness. This study explores the orchid diversity in Kozhikode District, Kerala, India. A total of 57 species belonging to 28 genera were identified within the study region. Among the total, 42 were epiphytic species and 15 species were terrestrial. Additionally, 16 species were identified as endemic to India, of which, 10 species were exclusive to the Western Ghats, four species to the Western and Eastern Ghats, and two species to peninsular India. Previous studies conducted within this region, only recorded 10 species. The present study, however, adds new records of 47 species to the orchid diversity of Kozhikode.


INTRODUCTION
Orchids are abundant in the humid tropics and subtropics of the world. They are known for their attractive colour, beautiful structure, and long vase life of the flowers. Orchids play an important role in horticulture trade due to their aesthetic appeal.
Horticulturalists show a huge interest in orchid hybrids, which are among the most highly valued horticultural plants in mass-market trade (USDA 2019). Besides the floriculture importance, the orchids face overexploitation for medicinal practices and are included in the threatened categories (Jalal et al. 2014). Due to the threatened status of orchids, different frameworks and acts are established by international agencies and the Indian Government with the aim to provide legal protection to conserve native orchid diversity.  (Nayar et al. 2014). Moreover, the Western Ghats and the state of Kerala have been reported to host a high level of orchid endemism with 111 endemic species in the Western Ghats, and 22 species that are exclusively endemic to Kerala (Singh et al. 2015).
Kerala is known to be rich in orchid diversity. The first research study that aimed to create an inventory of orchid species in Kozhikode District, Kerala was 32 years ago. The study resulted in recording only 10 species (Manilal & Sivarajan 1982). Ever since, most researchers have mainly focused on identifying new species. Thus the present work aims to build upon the study that was conducted by Manilal & Sivarajan (1982) and bring out a more comprehensive inventory of orchid species in Kozhikode District, Kerala.
As the natural ecosystem is highly threatened by multiple anthropogenic stressors, it is imperative to periodically estimate the floral wealth in a region. The orchids are adapted to live in a specialized environment because of their specialized requirement and many species are very restricted in distribution and endemism is very high (Nagrare 2006). Any destruction or degradation of natural habitat beyond a tolerable limit cause threat for their survival. Hence the present study also necessitates to survey and study the orchid diversity and distribution of an area in regular period.

Study Area
Kozhikode is one of the coastal districts in Kerala. It is bound by Kannur district in the north, Wayanad district in the east, Malappuram district in the south, and the Lakshadweep Sea in the west. It lies between north latitudes 11.140-11.835 and east longitudes 75.508-76.137. It has a forest cover of 1,493 km 2 (Economic Review 2019). The study areas, viz., Kakkad, Kakkayam, Kuttiyadi, Malabar Wildlife Sanctuary, Puduppadi, Peruvannamuzhy, and Thamarassery were selected as they are composed of different forest types such as: tropical semi-evergreen forest, tropical evergreen forest, and grasslands (Table 1). In the year 2019, Kozhikode recorded an annual rainfall of 3,205 mm. The minimum temperature in this region ranges between 22 and 25.8 0 C and the maximum between 28.2 and 32.9 0 C. The temperature reaches its peak in the month of April. The zonal relative humidity ranges 74-92 % during the morning hours and 64-89 % in the evening hours ( Figure  1).

Field survey
Explorations on orchids at Kozhikode were carried out from January 2018 to December 2019. The random survey succeeded through frequent visits in all seasons

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and locating the orchids in tropical semi-evergreen forest, tropical evergreen forest, and grasslands of Kozhikode, Kerala. Normally about three specimens were collected with reproductive structures while single specimen was collected for the orchids with least population or an uncommon species. The terrestrial or ground orchids were collected leaving the tuber or rhizome for regeneration and epiphytes were collected using sticks without disturbing its population. The non-flowered orchids were collected and planted in the botanical garden of the Botanical Survey of India, Coimbatore and upon flowering of the species the identification was carried out.
The field notes included names of the flora, habit, habitats, species name, family, flowering, fruiting, date of collection, collection number, collectors, and remarks. In addition, the geo-coordinates and elevation of the orchids were recorded using GPS-Garmin and digital photos were taken using a Nikon D300s Camera for future reference.
After gathering the plant materials, herbarium was prepared using standard herbarium techniques such as poisoning, drying, mounting, and labelling (Jain & Rao 1976). The specimens were identified using relevant literature, regional and national floras (Abraham & Vatsala 1981;Ansari & Balakrishnan 1990;Gamble 1928;Kumar & Manilal 2004;Misra 2007;Sasidharan 2013;Singh et al. 2015Singh et al. , 2019, as well as specimens examined at regional and national herbaria, namely, Madras Herbarium (MH), Tropical Botanic Garden and Research Institute (TBGT), Kerala Forest Research Institute (KFRI), and University of Calicut (CALI). The mounted specimens were labelled with accessed number and deposited in the Madras Herbarium (MH), Botanical Survey of India, Southern Regional Centre, Coimbatore, Tamil Nadu.

Floristic diversity
This study was conducted as an attempt to create an inventory of orchid species from Kozhikode. A total of 57 species of orchids, belonging to 28 genera were identified as a part of this study ( Table 2). The orchids were categorized based on habitat type, and it is noted that, among the total, 42 species are observed to be epiphytic and 15 species are terrestrial. The above collection also included 16 orchid species which are endemic to India. The most dominant orchid genera in Kozhikode are Dendrobium (8 spp.), Oberonia (7 spp.), Bulbophyllum and Habenaria each (4 spp.), and Liparis (3 spp.). Eight genera are represented by two species each, while the 13 genera have one species each. (Figure 3).

DISCUSSION
The land of Kozhikode is endowed with forests, wetlands and beaches. In the past, many academics, botanists, and scientists have conducted expeditions to explore the floristic diversity of this region (Ellis et al. 1967;Manilal & Sivarajan 1982;Chandra & Azeez 2010). The results of those expeditions include, discoveries of    1982). Upon analyzing the study area, same level of plant richness was observed. Besides, it is also noted that previous researchers has focused more on floristic aspects rather than concentrating on specific groups like Orchidaceae.
The new distributional findings of the 48 orchid species were mainly found in Kakkayam (tropical evergreen forests), Malabar Wildlife Sanctuary (tropical semi-evergreen forests, tropical evergreen forests, and grasslands), Kakkad & Pathuppadi (tropical semievergreen forests), and Kuttiyadi, Peruvannamuzhy, & Thamarassery (tropical semi-evergreen forests and tropical evergreen forests) (Image 1-4). A majority of the species from the survey was found in tropical evergreen forests (25 species). At high elevations the tropical semievergreen forests hosted the second highest diversity of 17 species, while in comparison, at lower elevation the diversity of orchids was relatively less, i.e., 10 species. Orchid diversity within grasslands was the lowest with five species (Figure 4).
The high number of orchid flowerings are observed between the months of August to December and others between the months of January to June. The endemic genus for the Western Ghats of Smithsonia maculata and S. straminea are excellent collections from the study area. Oberonia josephii, previously known only from Wayanad, is now included in this collection as a secondary addition. An interesting species, Eulophia zollingiri known for its rare blooming was recorded and conserved with other orchids as ex situ conservation at the botanical garden, Botanical Survey of India, Coimbatore. Hence, this work also highlights the presence and distribution of species is the first step in determining areas of conservation and conservation strategies.

CONCLUSION
The present findings resulted in recording the new distributions for 47 species of orchids in Kozhikode; as the earlier records has indicated only 10 species. This study also confirms the importance of conducting repeated field surveys in the study area to bring out a comprehensive inventory of orchid species. In addition, it also helps in documenting the changes happening in forest cover and land use finally identifying the threat factors of the vegetation. Thus it is concluded that inventory of any floristic elements is quite essential to assess the diversity of a given area and it act as a baseline data to suggest the appropriate conservation measures in the future timescale.