Grasses of Odisha

    

    Poaceae are estimated to have about 11,506 species belonging to 768 genera (Soreng et al., 2017) in the world. In India, it has about 1506 species belonging to 261 genera (Kellogg et al. 2020), which contributes to about 11 % of the world's species. In Odisha, it is represented by 271 species under 104 genera. Odisha has 4 endemic grasses viz., Themeda mooneyi, Themeda odishae, Themeda saxicola and Tripogon mahendragiriensis. Grasses, despite their economic and ecological importance and rich diversity, the taxonomic studies have taken a back seat due to miniature floral parts, look-alike nature in general appearance, and specialized terminology associated with its morphology. In Odisha, grass collections were initiated by D. Walsh from 1888 to 1889 from Puri, Khurda, Cuttack, and Ganjam regions. Many of his collections are deposited in CAL (Herbarium - BSI, Howrah) and DD (Herbarium - FRI, Dehradun). Among his collections, Iseilema jainiana (=I. laxum) from Khurda collected in 1888 might be the oldest collection (s.n.), this sheet doesn’t have any number on it. Collections of Haines, Mooney, and Raizada are mostly present in DD with a few representatives at CAL. Some of the important collectors whose specimens are present in CAL are by G. Panigrahi, P. C. Nanda, L. K. Banerjee, D.C.S. Raju and A.R.K. Sastry. IMMT (formerly, RRL) Bhubaneshwar also possesses many grasses collections from Odisha mostly done by Saxena & Brahmam. As there were no dedicated taxonomic studies on ‘Poaceae’ for Odisha state, the present work was carried out during 2011-2018. All specimens collected during the present work are deposited in BSID, Hyderabad. The classification adopted in this work is based on “A Worldwide Phylogenetic Classification of the Poaceae” by Soreng et al. (2017). This book does not include Bamboos which come under the sub-family Bambosoideae. 

Niyamgiri hills in Eastern Ghats

  

Spinifex littoreus (Burm. f.) Merr. population in Ganjam coast. 

 

Study Area:

    The Odisha state (area: 1,55,707 km2) is situated on the east coast of India. It is surrounded by Andhra Pradesh in the South, Chhattisgarh in the West, Jharkhand in the North, West Bengal in the East, and the Bay of Bengal in the Southeast. It has 480 km of coastline. The state has 30 districts divided into 3 divisions namely North, Central, and South. It is bestowed with varied physiographic regions, moderately high rainfall with 142.2-157.5 cm precipitation per annum and relative humidity of 61.5-78.0%, and a fine network of perennial river systems. The state has about 37% forest cover which can be categorized into 5 of the sixteen major forest types and 32 sub-types occurring in India (Champion & Seth 1968).

    The 5 main categories of forests are (i) Semi-evergreen (ii) Tropical moist deciduous (iii) Tropical dry-deciduous (iv) Central India hill forests and (v) Littoral and Tidal swamp forests (Panigrahi, 1983).

Biogeographically, the state falls in 3 zones viz., Deccan Peninsula (Chota Nagpur and the Eastern Highlands), Lower Gangetic Plain (7B), and East Coast (8B) as per classification by Rodgers et al., (2002). Meher-Homji (2001), has recognized 3 phytogeographic regions in the state, i.e., Deccan Plateau, Eastern Ghats, and the Coastal Plains. The state is underlaid covered largely by the Precambrian rocks. The geological formations reflect a complex of igneous, metamorphic, and sedimentary rocks with alluvial and coastal alluvial plains, each giving rise to distinct soil types with a range from alluvial (coastal and riverine types) to lateritic and Black cotton.

Oryza meyeriana (Zoll. & Moritzi) Baill.

Pseudosorghum fasciculare (Roxb.) A. Camus

Past Work:

    A review of published literature related to Odisha reveals that 3,000 species of Angiosperms and Pteridophytes have been recorded from the state (Saxena & Brahmam, 1996). The flora of the state is mainly known through the works of H. H. Haines (1921-1925) “The Botany of Bihar and Orissa” and H.F. Mooney’s (1950) “The Supplement to the Botany of Bihar and Orissa”. These works serve as the basis for further floristic studies in the state. The Floristic account on the Southern part of Odisha which was then part of the Madras Presidency was given in Gamble’s (1915-36) in “Flora of Madras Presidency”. Other notable floristic works are by Panigrahi et al. (1964), Rao & Banerjee (1967), and Saxena & Brahmam (1994-96). Apart from this, a few studies that have contributed to the knowledge on the grasses of the state are by M. B. Raizada (1948), S. L. Kapoor (1964), S. K. Jain (1975), S. C. Mishra et al. (1983). Poaceae was dealt in these floras as a part of general floristic work, but there was no comprehensive account on the grasses of Odisha state. Hooker’s (1896) ‘Flora of British India’ does not specifically mention ‘Odisha’ for the occurrence of grass species. Haines (op. cit.) had recorded 85 species and 3 varieties of grasses in the Botany of Bihar & Orissa. Fischer (l. c.) in Flora of Madras Presidency document 17 species from the southern districts of Odisha which were in the erstwhile Madras Presidency. H.F. Mooney (l. c.) has added 103 species of grasses to the state. Saxena & Brahmam (1996) in “Flora of Orissa state” had reported 250 species belonging to 98 genera. S. Panda & A. P. Das (1995) and P. C. Panda & S. N. Patnaik (1996) have documented the grasses of Sambalpur and Puri districts respectively.

Diversity: 

    In Odisha, the family Poaceae is represented by 271 species belonging to 104 genera under 15 tribes. A comparison of the number of species under different tribes shows that Andropogoneae and Paniceae tribes are dominant, represented by 99 and 67 species. In India, Poaeae is the third largest tribe (with 116 species) and in Odisha, Cynodonteae is the third largest tribe with 33 species. 

Dominant grass genera in Odisha are Eragrostis (19 species) and Panicum (12 species). 53 genera are represented by only 1 species. The most dominant genera in Andropogoneae is Themeda (9 species), followed by Cymbopogon (8 species). Comparison of dominant genera of Odisha and India shows that genus Themeda shows maximum diversity as compared to other states; in Odisha, it has 9 species (20 species in India).

    In India, 14 genera and 315 species of grasses are reported to be endemic (Kabeer & Nair, 2009).  Among 315 endemic grasses, 19 species occur in this state, including 2 newly described taxa. 4 species viz., Themeda mooneyi Bor, Themeda odishae Chorghe et al., Themeda saxicola Bor, and Tripogon mahendragiriensis Chorghe et al. are strictly endemic to Odisha. Their distributions are known only from type collections and hitherto they are not recollected from other localities. The geo-coordinates of all endemic species were taken and presented on the map.

Distribution Pattern:

    Biogeographically, Odisha is divided into 3 major divisions viz., Chota Nagpur Plateau, Eastern Ghats, and Mahanadi River basin. Chota Nagpur Plateau comprises the moist deciduous forest dominance of Shorea robusta. In Eastern Ghats hills, valleys are covered with dense forest and thus no grasslands can be seen. But, where the altitude is above 800 m a. s. l., there are a good number of grasslands on the top of the hills. The Mahanadi River basin is a plain area and mostly comprises the deltaic region of various rivers. This region is densely populated and the land is widely used for cultivation. Grasses will be seen growing along River banks and marshy lands. According to Dabadghao and Shankarnarayan (1973), the grasslands of Odisha can be classified as Sehima-Dichanthium type. Odisha state with diverse vegetation types, grasslands can be divided into two major types, Low-altitude grasslands, and High-altitude grasslands.

(i) Low-altitude grasslands: These grasslands are found up to 800 m a.s.l. Dominant grass genera here are Dichanthium, Eragrostis, Sehima, etc. in drier regions, Brachiaria, Echinochloa, Phragmites, Saccharum, etc. in Wet regions, and Aristida, Digitaria, and Heteropogon in degraded arid-semi-arid habitats.

(ii) High-altitude grasslands: This can be found above 800 m a.s.l. in Eastern Ghats hills like Niyamgiri, Mahendragiri, and Deomali. Dominant grasses in these grasslands are Dimeria, Garnotia, Jansenella, Themeda & Tripogon.

In addition to these primary types of grasslands, grasses can be divided according to habitat specificity. Following are some habitat-specific grasses observed in Odisha:

(i) Rocky Habitats: Many Grasses that are adapted for growing on rocks and rocky crevices are generally annuals and require comparatively less water and nutrients, they complete their life cycle when there is the availability of water. Grasses like Dimeria orissae, Dimeria ornithopoda, Garnotia tenella, Jansenella griffithiana, Microchloa indica, etc., occur here. Perennial grasses growing in rocky crevices possess rootstocks, whenever there is the availability of water they grow and in the dry season they will be dormant. Grasses like Arthraxon lancifolius, A. nudus, Arundinella setosa. Eragrostiella bifaria, E. brachyphylla, Oropetium thomaeum, O. villosum, Pogonatherum crinitum, Tripogon bromoides, T. jacquemontii, etc.

(ii) Sandy Habitats: Spinifex littoreus, Trachys muricata etc., grows on sandy coast. Grasses like Aristida adscensionis, A. funiculata, Dactyloctenium aegyptium, Chrysopogon zizanoides, etc., grow on the sandy banks of rivers and streams.

(iii) Wetland grasses: Coix lacryma-jobi, Hygroryza aristata, Hymenachne acutigluma, Leersia hexandra, Panicum curviflorum, Paspalidium flavidum, Paspaplum vaginatum, Phragmites karka, Pseudoraphis spinescens, etc. generally occur in wetlands

(iv) Cultivated landscapes: Eleusine coracana, Oryza sativa, Sorghum bicolor, Saccharum officinarum, Triticum sativum, Zea mays, etc., are cultivated in the state. Along with this cultivated species, weedy species like Eleusine indica, Ischaemum rugosum, Oryza rufipogon, Saccharum spontaneum, Sorghum halepense, etc. are commonly seen.

(v) Wasteland: In degraded habitats and fallow lands, grasses appear first and colonize rapidly. A few examples are Alloteropsis cimicina, Aristida adscensionis, Chloris barbata, Dichanthium annulatum, Heteropogon contortus, etc.

NOTABLE FINDINGS

    Present taxonomic studies on Odisha grasses have resulted in documenting 271 species belonging to 104 genera. Critical observations have led to the discovery of novelties and new distributional records to the state as detailed below. 

NEW SPECIES DISCOVERED

Tripogon mahendragiriensis Chorghe et al. is described as a new species from Mahendragiri Hills in Gajapati District at 1400 m a.s.l. this novelty is allied to Tripogon humilis and T. purpurascens.

Themeda odishae Chorghe et al. also described from Mahendragiri Hills in the Gajapati District found between 1300 to 1400 m a. s. l. It is closely related to Themeda mooneyi.

NEW RECORD FOR PENINSULAR INDIA

Phacelurus zea (C. B. Clarke) Clayton is robust grass growing in swampy, wet habitats. Its distribution ranges from China to Northeast India. This collection forms a first time report to Peninsular India from Similipal Biosphere Reserve, Mayaurbhanj District of Odisha (Chorghe et al., 2013).

NEW DISTRIBUTIONAL RECORDS TO ODISHA

Arundinella ciliata (Roxb.) Nees ex Miq. is an endemic grass to India. It was collected from Niyamgiri hills in Odisha state and reported as new for the state. Before this, it was reported from Andhra Pradesh, Karnataka, Kerala, Maharashtra, and Tamil Nadu (Chorghe et al., 2013).

Isachne pulchella Roth was previously reported from Andhra Pradesh, Madhya Pradesh, Maharashtra, West Bengal, Tamil Nadu, and South East Asia. It is now collected from Similipal Biosphere, Odisha state (Chorghe et al. 2015).

Lophopogon kingii Hook. f. is an endemic species previously known only from Monghyr, Bihar. It is now reported from Satkosia Wildlife Sanctuary, Odisha (Chandramohan, et al. 2016)

Ottochloa nodosa (Kunth) Dandy is distributed in South East India. In India, it is reported from North- East India, Karnataka, Kerala and Tamil Nadu. It is now collected from Kuldhia Wild life Sanctuary in Balasore district, Odisha state.

Schoenefeldia gracilis Kunth is distributed in Africa, Tropical, and Temperate Asia. In India, it is reported from Bihar, Madhya Pradesh, Maharashtra, and Uttar Pradesh. It is now collected from the Talkudar forest region in Sundargarh district, Odisha state (Chorghe et al. 2015).

Other significant findings:

· Oryza jeyporensis Govindasw. & K. H. Krishnam. is treated as a synonym of Oryza rufipogon Griff. as the character mentioned in protologue completely matches with it.

· Dimeria mahendragiriensis Ravi, H. O. Saxena & Brahmam has been reduced as a synonym of Dimeria fischeri Bor. This conclusion was made after doing critical studies of speciemens collected from type locality and Holotype of D. mahendragiriensis available in RRLB.

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