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Introduction Poaceae (R.Br.) Barnh. is the fourth largest family of flowering plants. It includes about 700-800 genera and 10,000-11,000 grass species distributed worldwide (Clayton & Renvoize 1986, Watson & Dallwitz 1999, Tropicos 2011). Grasses occur in nearly all the ecosystems and habitats of the world (Clayton & Renvoize 1986, Ture & Bocuk 2007, Osborne et al. 2011) and provide cover to nearly a fifth of the land surface (Shantz 1954, Arabaci & Yildiz, 2004, Brooks et al. 2004). Several studies have dealt with spatial and temporal frame for the origin and diversification of grasses and allied plant types. Attempts have been made to construct the paleo-ecological and paleo-biogeographical maps and paleo-historical calenders to trace major evolutionary events that lead to differentiation of various clades first among families of the order Poales and later between and within families of the graminoid clade. Fossil evidences coupled with comparative molecular genomics and physiological status of present day species have been utilized to reconstruct the evolutionary history and understand the past and present distribution of various groups of grasses. Bremer (2000) postulated the origin of order Poales in the mid-Cretaceous (115± 11 mya). Early differentiation of Poales has been located in Southern continents breaking away from the Gondwanaland (Dahlgren et al., 1985). Fossil pollen referable to graminoid families Poaceae and Restionaceae has been recovered from the Late Cretaceous (>65 mya) which point to evolution of grasses by this time (Linder, 1987). But, the typical spikelets that mark the origin of the earliest grasses have been reported no earlier than 55 mya at Paleocene-Eocene transition in the Coenozoic (Crepet and Feldman, 1991). Taxonomic diversification and geographic diversification occurred during the Eocene in several phases beginning with the crown node of bambusoid grasses (53mya) and continuing with the pooid (47-38 mya), chloridoid (35-25mya) and panicoid (26mya) groups (Klootwijk et al. 1992, Kellogg 2001, Bouchenak-Khelladi et al. 2010). With their origin in the southern land masses, grasses are believed to have spread to Eurasia via the Indian land mass (Klootwijk et al. 1992). Grasses comprise a remarkable group of plants with unmatched economic and ecological importance. Their relevance and importance to mankind can hardly be over emphasized. Ever since the origin of agriculture, grasses have occupied the centrestage of human subsistence and economy. All our cereals and millets are grasses that have been 1 Introduction cultivated since millennia. Sugarcane, the main source of sugar around the world also belongs to the family Poaceae. In fact, human civilization developed only after successful cultivation of cereal and fodder grasses of various kinds. Apart from food and fodder, several grasses are used for extraction of aromatic oils and scents (Kaul & Vats 1998, Khanuja et al. 2005, Kim et al. 2005, Bhuiyan et al. 2008, Sujatha, 2010). Grasses also provide green cover to our lawns and landscape for tourism and sports. Their use in handicraft and cottage industry is well known. The ecological role of grasses is equally significant. They constitute the most ubiquitous component of the terrestrial vegetation of the entire globe ranging from tropical to the polar and rain forests to the arid. Their roots and creeping rhizomes and stolons act as efficient soil builders and soil binders. Thus, grasses act as pioneers in plant succession and prepare the ground for soil and overground flora and fauna. In terms of abundance and frequency, they outnumber manifold any other group of plants. Vegetation types having a stratified structure topped by tree canopies harbour low growing grass species that occupy the understorey and the ground strata. But, open and exposed vegetation zones are dominated by tall grasses. These landscapes called grasslands are known by colloquial terms in different parts of the world. The open and flat landscapes of southern Africa overgrown with a mixture of small grasses and low scrub are called ‘Velds’ which is the English rendition of the Afrikaan word for ‘field’. Grasslands developing in rain shadows of mountains in North America are called ‘Prairies’ literally meaning ‘meadows’. Generally, a ‘Prairie’ does not have enough rainfall and soil moisture to support growth of trees leaving the terrain open for growth of tall grasses and the grasslands. Grasslands developing in the semiarid and continental climate marked by extremes of summer high (upto 400C) and winter low (down to -40oC) temperatures and a profusion of shorter grasses of semiarid zone are called ‘Steppes’. They occur in cold continental climate of Eastern Europe and Central Asia but ‘Steppe like’ grasslands are also encountered in semiarid and subtropical regions of the world marked by a moderate rainfall and high evapotranspiration. In India, the semiarid land fringing the Thar Desert supports a ‘Steppe-like’ grassland. However, a majority of grasslands of India are ‘Savannas’ which are defined as grassland ecosystems with a remarkable representation of trees that dot the landscape but are so widely spaced that 2 Introduction they leave large gaps in the canopy for sunlight and luxuriant growth of hardy grasses. Thus, Savannas are ecosystems that have a more or less continuous grass cover but discontinuous tree cover (Scholes and Archer 1997). Despite comparatively recent origin and diversification, grasses have come to have cosmopolitan distribution and dominance in some of the ecosystems outwitting even trees and other elements of the ground flora. Several attributes of grasses have contributed to their wide distribution, perpetuation and occasional dominance in some ecosystems called the grasslands. Among growth characteristics is a dense and fibrous root system that explores and exploits soil water and nutrients more actively than arborescent elements (Partel and Wilson 2002). Apart from an efficient utilization of soil resources, grasses, particularly in the tropics, have deep seated buds below the ground surface safe from forest fires which obliterate woody samplings (Mouillot and Field, 2005). Apart from ecology, grasses have a highly efficient reproductive strategy combining contiguous spread by vegetative means and non-contiguous dispersal to new locations through sexual diaspores. Grasses have higher survival and biomass productivity due to the existence of alternative C4 route of carbon assimilation in hot tropics that induce photorespiration in C3 plant species. The C4 grasses show a syndrome of anatomical and biochemical adoptions that help to minimize photorespiration and fix CO2 precisely at anatomical sites of fixation (Sage, 2004, Edwards et al. 2010). The C4 cycle has allowed grasses to spread in several drier tropical and subtropical habitats (Osborne & Freckleton 2009, Edwards and Smith, 2010). In humid Savannas, C4 grasses reach high levels of biomass production. Besides ecology, grasses possess tremendous taxonomic significance. Owing to a peculiar and distinctive morphology, the grass plant is a taxonomic novelty. As such, grasses have always attracted the attention of naturalists and plant systematics. Landmark contributions of Nash (1903), Hitchcock (1914, 1920 & 1933), Stebbins (1956), Bor (1960), Gould (1968) and Gould and Shaw (1983) provided a firm foundation to grass systematics. Thereafter, information on diversity and distribution of grasses has steadily increased by the noteworthy contributions of Clayton & Renvoize (1986) and Watson & Dallwitz (1992). The establishment of Grass Phylogeny Working Groups (GPWG I & II) have provided grass systematists of the world the much needed forum for guidance and 3 Introduction exchange of information. Worldwide checklists of grass species with notes on phytogeographic distribution have become a point of reference for researchers across the globe. In their systems of classification of the family Poaceae, GPWG I (2001) and GPWG II (2012) have recognized twelve subfamilies instead of only five or six by relocation of genera and splitting of taxa. Evidences for this phylogenetic classification have been drawn not only from morphology but also from molecular data or combinations of both the approaches (Salamin et al., 2002, Peterson et al. 2012, Jones et al. 2014). Within subfamilies, large and complex genera have been revised (Saarela et al. 2003, Spangler 2003, Molina & De Agrasar 2004, Finot et al. 2005, Zuloaga & Morrone 2005, Paszko 2012, Baum et al. 2014, Veldkamp 2014). Apart from reclassification, recent studies have brought to light possible evolutionary changes that have lead to the characteristic grass morphology and anatomy. Such studies have brought to light the phylogenetic route and temporal frame for such fundamental questions of grass organography as development and organization of the spikelet (Kellogg, 2001), petaloid nature of the lodicules (Ambrose et al. 2000) and origin of the C4 anatomy and physiology (Gaut & Doebley 1997, Kellogg, 2001, Christin et al., 2008, Edwards and Smith, 2010). Owing to their cosmopolitan distribution and a finely timed phenology, grasses have emerged as a model group of biological indicators for climatic and environmental change. Grass species exhibit several clearly defined phenophases in their phenological cycle. Each of the phases namely the bud burst, the boot formation, inflorescence emergence, fruit set and disarticulation of the diaspores are precisely timed events in the yearly cycle. Several studies have attempted to utilize grasses as models of environmental change through an empirical delimitation of parameters controlling these phenological shifts (Buzzaz, 1991; Thornley and Cannell, 1997; Steinaker et al., 2010). A high degree of seasonal and habitat specificity make grasses an ideal choice as environmental indicators. In India, two important factors lend a place of privilege to grasses and the grass flora. Firstly, the tropical climate of the country is mainly responsible for creation and perpetuation of grasslands. Dabadghao and Shankarnarayan (1973) argued that large chunks of Indian territory traditionally classified as forests are actually grasslands. The 4 Introduction authors identified five types of grass covers for the country and also listed out the forest types whose physical boundaries coincide with these grass covers. The authors also argued that the grasslands of India are edaphic rather than vegetational climaxes and that they are perpetuated through continuous biotic disturbances that disrupt the tree canopy and do not allow these grasslands to succeed into woodlands. The second important factor for the predominance of grasses is the agrarian economy heavily dependent upon cultivation of cereals and millets for human food and animal fodder. Agricultural fields throughout the territorial expanse of the country are simply monocultures of about a dozen grass species. Within the country, grasses assume even greater importance in regions like Punjab which have a land use heavily biased towards intensive agriculture. Despite overwhelming significance of grasses and grasslands in the country and an upsurge in grass systematics the world over, India has been categorized as a ‘seriously undercollected’ country as far as diversity and systematics of grasses is concerned (Kellogg, 2006). Nevertheless, an enthused interest in grasses throughout the world has given an impetus to research on different aspects of Indian grasses. Given the fact that cultivated grass species constitute the mainstay of our agrarian economy and wild grasses dominate our subtropical/tropical ecology, this is a significant development. Research publications have reported new species and genera (Ravi et al. 2001, Potdar et al. 2003, Salunkhe and Potdar 2004, Sunil and Pradeep 2005, Kabeer and Nair 2007, Kiran Raj and Sivadasan 2008, Yadav et al. 2010, Raole et al. 2011, Kiran Raj et al. 2013). Besides taxonomy, research in grasses has recently been extended to other aspects including ecology (Yadava 1990, Kunhikannam, 2008, Reshi et al. 2009), physiology (Nath, 2004), reproductive biology (Kaushal et al. 2004, 2005), molecular biology and genetic diversity (Chandra et al., 2004, Saxena & Chandra, 2006) and dispersal strategies (Sharma et al. 2010). Punjab, the area of present investigation, has a predominance of grasses both in the wilderness as also the cultivated fields. It is practically a ‘grassland of cultivated species’ or a ‘cultivated grassland’. Besides cultivated fields, grasses constitute the dominant elements of rangeland vegetation and ecology of the region. But, grasses have not been given sufficient attention in floristic compilations of the region. Some of the earliest works made no mention of the group (Bamber 1916, Kashyap 1936). Others have 5 Introduction given only an alphabetic list of species with sketchy descriptions (Stewart 1869, Sabnis 1940, Nair 1978, Sharma & Bir, 1978). It is only in the work of Sharma & Khosla (1989) that grass species were given a systematic treatment. Our research group has initiated work on systematic inventorization, taxonomic description and characterization of the grass species of Punjab and adjoining hills according to the latest format and systems of classification (GPWG I, 2001 and GPWG II, 2012). We have made some headway in grass systematics by preparing an updated conspectus of grasses (Soodan et al. 2012) and taxonomic descriptions of some hitherto undescribed species (Kumar and Soodan 2013). Besides taxonomic update and species characterization, the group is actively pursuing phytosociology (Soodan et al., 2009) and dispersal and facilitated propagation of grass species of the region (Soodan et al., 2012). The present work was planned with the following objectives in mind. 1. To explore the three plain regions (Doabs) of Punjab along with neighbouring hills for diversity of grasses through intensive field surveys and collections. 2. To prepare an updated conspectus of grasses of Punjab through a comparative study of past reports and present collections. A possible outcome of this study would be some new reports of grass species from the region. 3. To identify and undertake detailed taxonomic description of the collected species according to the latest formats of descriptions available online at ‘GrassBase-the Online World Grass Flora’ at http://www.kew.org/data/grasses-db. html. The descriptions are maintained by Clayton, WD, Vorontsova, M.S., Harman, KT, Williamson, H. (2006 onwards)’ for The Board of Trustees, Royal Botanical Garden, Kew, U.K. 4. To complement the textual descriptions of the past compilations and past work with spikelet formulae and spikelet diagrams by appropriate modifications required for various groups of grasses. The sources for basic scheme of these diagrams and formulae are given in the third chapter of this thesis. 5. To work out etymological derivation and grammatical structure of generic names and specific epithets of grass species for ready reference of grass systematists and students. A note on the etymology of each species would provide useful hints about the nature of the grasses encountered in the field. 6 Introduction 6. To classify grass species of the study area according to the latest scheme of the grass classification proposed by Grass Phylogeny Working Group I (2001) and modified by GPWG (2012). A user friendly key to various taxa down the taxonomic hierarchy is also an objective of the present study. 7. To provide information about seasonal distribution and habitat preference of grasses of the region for ready reference by students and agrostologists interested in the academic and applied study of grasses of the region. Another objective was to decipher the types of grass covers and their annotation to the accepted classification of grass covers of the country (Dabadghao and Shankranarayan, 1973). 8. To develop the departmental herbarium into a nodal centre of reference for grasses of the region through collection and preservation of herbarium sheets of the collected specimens. 7