Bamboo Systematics with Special Reference to Molecular Taxonomy of Dendrocalamus 3

Bamboo Systematics with 1 Special Reference to Molecular Taxonomy of Dendrocalamus Swapnendu Pattanaik 1. Bamboo Systematics – A Historical Perspective Bamboos have always been a taxonomically challenging group of plants because while the classification of flowering plants depends largely on the characteristics of reproductive organs, flowering is rare in many bamboo species. Some bamboo species flower at intervals as long as 120 years and for some there is no report of flowering to date. The first classification of bamboos was attempted by Carl Sigismund Kunth (Kunth, 1815) who made the bamboos (Graminae Bambusaceae) one of 10 groups in his natural system of classification of grasses, thus, conceptualizing what is today subfamily Bambusoideae. Further progress in the classification of the Bambusoideae was provided by Christian Gottfried Daniel Nees von Esenbeck (Nees von Esenbeck, 1835) in his treatment of Brazilian bamboos, when he recognized two woody (Bambuseae and Arundinariae) and one herbaceous (Streptochaeteae) group. This was soon followed by the first worldwide treatment of bamboos 'Bambuseas Monographic' by Frank Joseph Ruprecht (Ruprecht, 1839), describing 9 genera and 67 species. Thirty years later Munro (1868) more than doubled this coverage, describing over 170 species in 20 genera, in what remains one of the most useful references on bamboos (Soderstrom, 1985). Munro's system was based on the foundation that Nees had laid down earlier but expanded to include many more taxa. Later Bentham (1883) modified Munro's scheme and in the account of Gramineae prepared for 'Genera Plantarum' included four sub-tribes under Bambusoideae: Sub-tribe 1- Arundinarieae (Arundinaria, Phyllostachys, Chusquea); Sub-tribe 2- Eubambuseae (Nastus, Guadua, Bambusa, Thyrsostachys, Gigantochloa, Oxytenanthera); Sub-tribe 3- Dendrocalameae (Dendrocalamus, Melocalamus, Pseudostachyum, Teinostachyum, Cephalostachyum); Sub-tribe 4- Melocanninae (Dinochloa, Schizostachyum, Melocanna, Ochlandra). The end of the 19th century saw appearance of another 2 Swapnendu Pattanaik significant monograph 'Bambuseae: The bamboos of British India' by James Sykes Gamble in 1896. Gamble adopted Bentham's scheme, covered 15 genera and 115 species mostly from India, Nepal, Myanmar and Malaysia. By the beginning of the 20th century, the study of bamboos had progressed further. Notable works in the first half of the century included Rendle's (1904) treatment of 44 bamboos from China, publication of Les Bambusees by Edmond Camus (1913) and a treatment of the bamboos of Assam by Bor (1938). Treatments had followed Bentham's scheme until Aimee Camus (1935) proposed a new scheme in which all genera having staminal filaments united to form a tube were placed in a separate subtribe. Subsequently, however, Holttum (1956) disputing the schemes of both Bentham (1883) and Camus (1935), offered a new classification based on the structure of the ovary. Holttum's scheme suggested a close relationship between Bambusa and Dendrocalamus on the basis of ovary features and he placed both in an informal 'subtribe' - Bambusa-Dendrocalamus type. In all, Holttum's system of classification included four sub-tribes A. Schizostachyum type (Melocanna, Ochlandra, Schizostachyum), B. Oxytenanthera type (Oxytenanthera), C. Bambusa- Dendrocalamus type (Melocalamus, Dinochloa, Thyrsostachys, Bambusa, Guadua, Dendrocalamus, Gigantochloa, Racemobambos), and D. Arundinaria type (Arundinaria). The woody bamboos have always been the basis of the concept of the bamboo group even though Nees had envisaged herbaceous bamboos in his scheme of Bambusoideae. Indeed, herbaceous bamboos were neglected in the schemes of Munro (1868), Bentham (1883), Gamble (1896), Camus (1913) and even the relatively modern scheme of McClure (1961). In that year, however, a paper was published by Prof. Lorenzo R. Parodi (1961) which brought into focus the bambusoid affinities of certain gramineous genera. Parodi defined Bambusoideae in a system of classification for the grasses of Argentina in which all woody bamboos were included in a single tribe (Bambuseae), but three further tribes were established for herbaceous members: Olyreae, Phareae, Streptochaeteae. As botanists began to look at plants more closely, from the evolutionary perspective, the significance of the herbaceous bamboos began to emerge and later authorities (Clayton and Renvoize, 1986; Soderstrom and Ellis, 1987; Watson and Dallwitz, 1992) all included herbaceous bamboos in a heterogeneous Bambusoideae (Clark et al., 1995). Among the modern traditional concepts of Bambusoideae, the circumscriptions of Watson and Dallwitz (1992) is considered to be the most inclusive, which contained 14 herbaceous tribes along with the woody bamboo tribe Bambuseae. In comparison, Soderstrom and Ellis (1987) separated the core Bambusoideae having five tribes (Anomochloeae, Buergersiochloeae, Olyreae, Streptochaeteae and Bambuseae) from those showing some relationships but lacking core Bambusoideae characters Bamboo Systematics with Special Reference to Molecular Taxonomy of Dendrocalamus 3 (1. embryo formula F+PP or F-PP, 2. a linear hilum, 3. smaller embryo in comparison to endosperm, 4. three lodicules, 5. first blade is horizontal in a seedling and preceded by one or more bladeless sheaths, 6. rod like bicellular micro hairs, 7. a nonradiate mesophyll and C3 photosynthetic pathway, 8. a mesophyll with both fusoid and arm cells present, 9. vascular bundles usually more than one and superposed in the midrib and 10. vertical orientation of silica bodies to the long cells) which were considered as part of Bambusoideae sensu lato. While the most recent taxonomic treatment 'The Bamboos of the World' by Ohrnberger (1999) provided a more restrictive view of Bambusoideae (Fig. 1.1.). Ohrnberger limited the tribal assignments to Bambuseae (woody bamboos) and five other herbaceous tribes including Puelia and Guaduella, though the inclusion of Puelia and Guaduella in Bambusoideae was tentative and later study (Clark et al., 2000) confirmed they should be excluded from the subfamily. They retained four of the core Bambusoideae described by Soderstrom and Ellis (1987) but moved Anomochloa, Streptochaeta, Phareae and other herbaceous tribes (as of Clayton and Renvoize, 1986; Soderstrom and Ellis, 1987; Watson and Dallwitz, 1992) out of Bambusoideae. Clayton and Renvoize (1986) provided a provisional classification of the woody bamboo tribe Bambuseae based on the ovary appendage as the primary criterion. By taking the genera in a wide sense and ignoring aberrant species, they referred the woody bamboos to three subtribes, viz., Arundinariinae, Bambusinae and Melocanninae. The subsequent schemes of Soderstrom and Ellis (1987) and Ohrnberger (1999) were more explicit and similar to a large extent. Soderstrom and Ellis (1987) delimited nine subtribes under Bambuseae and expressed uncertainty about the placement of a few genera, viz., Apoclada, Glaziophyton, Hitchcockella, Oligostachyum and Racemobambos. Whereas, Ohrnberger's scheme included 10 subtribes. He merged the Nastinae and Neurolepidinae of Soderstrom and Ellis (1987) in his subtribes Hickeliinae and Chusqueinae respectively, and placed the uncertain genera Apoclada and Glaziophyton in subtribe Arthrostylidiinae, Hitchcockella in Hickeliinae, Oligostachyum in Arundinariinae, and Racemobambos in Racemobambosinae. The Old World tropical subtribe 'Bambusinae' has been variously circumscribed by the modern sytematists. Clayton and Renvoize's (1986) scheme included 25 genera based on type of inflorescence, culm sheath characters and ovary characters. Later, Soderstrom and Ellis (1987) narrowed down the subtribe to six genera based on floral and vegetative key characters as other anatomical characters were found unhelpful at this level. He also placed ten other genera as congeners with Bambusa and Dendrocalamus. The circumscription of Wong (1995) was limited to the taxa available in Peninsular Malaysia. Besides retaining five genera of Clayton and Renvoize (1986), Wong (1995) described three new genera, which were initially included in Bambusa 4 Swapnendu Pattanaik by Holttum (1956). In the most recent scheme of Ohrnberger (1999), the subtribe Bambusinae embraced seventeen genera and 297 species. He retained seven genera of Clayton and Renvoize (1986) and the four additional genera described by Wong (1995) in his scheme of Bambusinae. He placed six other genera in Bambusinae taking total number of genera to 17. Many genera included in the scheme of Clayton and Renvoize (1986) were moved to subtribes Arthrostylidiinae, Hickeliinae, Shibataeinae and Racemobambosinae and some of the genera (Bonia, Gigantochloa, Oreobambos and Oxytenanthera) placed as congeners in Soderstrom and Ellis's (1987) scheme were given generic status. The fluctuating size of the subtribe Bambusinae over the years reflect the problem whether to combine taxa based on character similarities or to delimit taxa into subgroups based on key character differences which is not easy in bamboos as the boundaries of many bamboo genera are not well defined (Soderstrom and Ellis, 1987). As such, there are differences of opinion with regard to the placement of Dinochloa, Melocalamus, Oxytenanthera and Holttumochloa, in Bambusinae. 2. Molecular Taxonomy of Bamboos – The Modern Approach The bamboo taxonomists have long been trying different sources of taxonomically informative data for the classification because of apparent paucity of morphological characters in bamboos,

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