Osvaldo Morrone

A worldwide phylogenetic classification of the Poaceae (Gramineae)

Based on recent molecular and morphological studies we present a modern worldwide phylogenetic classification of the ± 12074 grasses and place the 771 grass genera into 12 subfamilies (Anomochlooideae, Aristidoideae, Arundinoideae, Bambusoideae, Chloridoideae, Danthonioideae, Micraioideae, Oryzoideae, Panicoideae, Pharoideae, Puelioideae, and Pooideae), 6 supertribes (Andropogonodae, Arundinarodae, Bambusodae, Panicodae, Poodae, Triticodae), 51 tribes (Ampelodesmeae, Andropogoneae, Anomochloeae, Aristideae, Arundinarieae, Arundineae, Arundinelleae, Atractocarpeae, Bambuseae, Brachyelytreae, Brachypodieae, Bromeae, Brylkinieae, Centotheceae, Centropodieae, Chasmanthieae, Cynodonteae, Cyperochloeae, Danthonieae, Diarrheneae, Ehrharteae, Eragrostideae, Eriachneae, Guaduellieae, Gynerieae, Hubbardieae, Isachneae, Littledaleeae, Lygeeae, Meliceae, Micraireae, Molinieae, Nardeae, Olyreae, Oryzeae, Paniceae, Paspaleae, Phaenospermateae, Phareae, Phyllorachideae, Poeae, Steyermarkochloeae, Stipeae, Streptochaeteae, Streptogyneae, Thysanolaeneae, Triraphideae, Tristachyideae, Triticeae, Zeugiteae, and Zoysieae), and 80 subtribes (Aeluropodinae, Agrostidinae, Airinae, Ammochloinae, Andropogoninae, Anthephorinae, Anthistiriinae, Anthoxanthinae, Arthraxoninae, Arthropogoninae, Arthrostylidiinae, Arundinariinae, Aveninae, Bambusinae, Boivinellinae, Boutelouinae, Brizinae, Buergersiochloinae, Calothecinae, Cenchrinae, Chionachninae, Chusqueinae, Coicinae, Coleanthinae, Cotteinae, Cteniinae, Cynosurinae, Dactylidinae, Dichantheliinae, Dimeriinae, Duthieinae, Eleusininae, Eragrostidinae, Farragininae, Germainiinae, Gouiniinae, Guaduinae, Gymnopogoninae, Hickeliinae, Hilariinae, Holcinae, Hordeinae, Ischaeminae, Loliinae, Melinidinae, Melocanninae, Miliinae, Monanthochloinae, Muhlenbergiinae, Neurachninae, Olyrinae, Orcuttiinae, Oryzinae, Otachyriinae, Panicinae, Pappophorinae, Parapholiinae, Parianinae, Paspalinae, Perotidinae, Phalaridinae, Poinae, Racemobambosinae, Rottboelliinae, Saccharinae, Scleropogoninae, Scolochloinae, Sesleriinae, Sorghinae, Sporobolinae, Torreyochloinae, Traginae, Trichoneurinae, Triodiinae, Tripogoninae, Tripsacinae, Triticinae, Unioliinae, Zizaniinae, and Zoysiinae). In addition, we include a radial tree illustrating the hierarchical relationships among the subtribes, tribes, and subfamilies. We use the subfamilial name, Oryzoideae, over Ehrhartoideae because the latter was initially published as a misplaced rank, and we circumscribe Molinieae to include 13 Arundinoideae genera. The subtribe Calothecinae is newly described and the tribe Littledaleeae is new at that rank.

Phylogeny of the Paniceae (Poaceae: Panicoideae): integrating plastid DNA sequences and morphology into a new classification

Included in the PACMAD clade of the family Poaceae (Panicoideae, Arundinoideae, Chloridoideae, Micrairoideae, Aristidoideae, Danthonioideae), the tribe Paniceae s.l. is one of the largest tribes of the subfamily Panicoideae, with more than 2000 species. This tribe comprises a huge morphological, cytological and physiological diversity represented by different inflorescence types, several basic chromosome numbers, and at least four major photosynthetic pathways. The tribe Paniceae has been the subject of molecular studies that have confirmed its paraphyly: two major clades were recognized based on their basic chromosome numbers (x = 9, x = 10). The x = 10 Paniceae clade is sister to the Andropogoneae–Arundinelleae s.s. clade (x = 10), while the combined x = 10 clade is sister to the x = 9 clade that contains the remaining genera of Paniceae. As a result of a recent realignment within the tribe in terms of the phylogenetic position of minor and major Paniceae genera, a reanalysis of the whole sampling is performed and new underrepresented taxa are discussed. A total of 155 genera, currently considered within subfamily Panicoideae, are represented here by almost all genera of Paniceae s.l., representatives of Andropogoneae and Arundinelleae s.s., and the endemic and small tribe Steyermarkochloeae; we also included specimens of subfamily Micrairoideae, tribes Isachneae and Eriachneae. The sampling includes as outgroups 18 genera of the PACMAD clade (excluding Panicoideae) and four genera from the BEP clade (Bambusoideae, Ehrhartoideae, Pooideae), rooting with Bromus inermis. A matrix with 265 taxa based on the combined evidence from ndhF plastid sequences (2074 bp) and 57 morphological characters was subjected to parsimony analyses. Jackknife resampling was used to calculate group support. Most clades are characterized by morphological, cytological, anatomical, and/or physiological characters. Major tribal changes are based on the basic chromosome number; the pantropical x = 9 clade is here recognized as Paniceae s.s., while the American x = 10 Paniceae s.l. is restricted to the reinstated tribe Paspaleae. The optimization of the photosynthetic pathway for the Paspaleae–Andropogoneae–Arundinelleae s.s. clade, including the monotypic Reynaudia, shows a plesiomorphic C4 state while the ancestral state for Paniceae s.s. is ambiguous. If Reynaudia were not included or placed elsewhere, the ancestral photosynthetic pathway for both the Paspaleae–Andropogoneae–Arundinelleae s.s. clade and the Paniceae s.s. would be unambiguously C3. In order to explore character evolution further, the morphological characters were mapped onto one of the most parsimonious trees. A relationship between photosynthetic pathways and inflorescence morphology is suggested here for the first time. Based on the optimization of morphological characters and additional data, we propose names for almost all inner clades at the rank of subtribe with a few groups as incertae sedis. With this extensive sampling, we resolved the phylogenetic relationships and the assignation of synapomorphies, and improved the support in subtribe sorting; consequently a robust circumscription of the tribe Paniceae s.l. is proposed.

Phylogenetic studies favour the unification of Pennisetum, Cenchrus and Odontelytrum (Poaceae): a combined nuclear, plastid and morphological analysis, and nomenclatural combinations in Cenchrus

BACKGROUNDS AND AIMS Twenty-five genera having sterile inflorescence branches were recognized as the bristle clade within the x = 9 Paniceae (Panicoideae). Within the bristle clade, taxonomic circumscription of Cenchrus (20-25 species), Pennisetum (80-140) and the monotypic Odontelytrum is still unclear. Several criteria have been applied to characterize Cenchrus and Pennisetum, but none of these has proved satisfactory as the diagnostic characters, such as fusion of bristles in the inflorescences, show continuous variation. METHODS A phylogenetic analysis based on morphological, plastid (trnL-F, ndhF) and nuclear (knotted) data is presented for a representative species sampling of the genera. All analyses were conducted under parsimony, using heuristic searches with TBR branch swapping. Branch support was assessed with parsimony jackknifing. KEY RESULTS Based on plastid and morphological data, Pennisetum, Cenchrus and Odontelytrum were supported as a monophyletic group: the PCO clade. Only one section of Pennisetum (Brevivalvula) was supported as monophyletic. The position of P. lanatum differed among data partitions, although the combined plastid and morphology and nuclear analyses showed this species to be a member of the PCO clade. The basic chromosome number x = 9 was found to be plesiomorphic, and x = 5, 7, 8, 10 and 17 were derived states. The nuclear phylogenetic analysis revealed a reticulate pattern of relationships among Pennisetum and Cenchrus, suggesting that there are at least three different genomes. Because apomixis can be transferred among species through hybridization, its history most likely reflects crossing relationships, rather than multiple independent appearances. CONCLUSIONS Due to the consistency between the present results and different phylogenetic hypotheses (including morphological, developmental and multilocus approaches), and the high support found for the PCO clade, also including the type species of the three genera, we propose unification of Pennisetum, Cenchrus and Odontelytrum. Species of Pennisetum and Odontelytrum are here transferred into Cenchrus, which has priority. Sixty-six new combinations are made here.

A global database of C4 photosynthesis in grasses

C3, C4 or Crassulacean acid metabolism (CAM) photosynthetic pathways represent a fundamental axis of trait variation in plants, with importance at scales from genome to biome. Knowing the distribution of these pathways among wild species is a crucial first step in understanding the patterns and processes of photosynthetic evolution and its role in ecological processes at large scales (e.g. changes in the composition of biomes under global change). C4 photosynthesis is most prevalent in the Poaceae (grasses), which account for about half of allC4 species (Sage et al., 1999a).Research on the evolution and ecology of these plants has undergone a renaissance during the last 7 yr, catalyzed by phylogenetic analyses showing multiple parallel C4 origins (e.g. Christin et al., 2007; Vicentini et al., 2008; GPWG II, 2012), insights into the distribution of C4 species and assembly of the C4 grassland biome (Edwards & Still, 2008; Edwards & Smith, 2010; Edwards et al., 2010), and efforts to introduce the C4 pathway into rice (Hibberd et al., 2008; von Caemmerer et al., 2012). C4 photosynthesis is an excellent model for investigating complex trait evolution, because of the broad knowledge base describing its biochemical basis, evolutionary history, and ecological interactions (Christin et al., 2010).

Systematic Revision and Phylogeny of Paspalum Subgenus Ceresia (Poaceae: Panicoideae: Paniceae)

Twenty-five species are treated in this work, in which exomorphological characters are analyzed cladistically. Species of Paspalum subg. Ceresia are characterized by their rigid, filiform to lanceolate blades, inflorescences with one to several racemes, rachis of the racemes winged and hyaline to membranous, spikelets pilose, occasionally glabrous, with the upper anthecium pale, hyaline to membranous, occasionally chartaceous, and the upper lemma not enclosing the tip of the upper palea. Species grow in South America from Mexico to Argentina and Uruguay. A cladistic analysis of subgenus Ceresia was conducted to test its monophyly, and to establish its relationship with other groups of Paspalum. A key to the species in subgenus Ceresia is given, as well as morphological description and illustration, and distribution maps.

Quantitative biogeography in the South America highlands—recognizing the Altoandina, Puna and Prepuna through the study of Poaceae

The distribution data of 340 grass species sampled in a region of 53.219 km2 in the northwestern corner of Argentina (between ∼21°S and ∼24°S) were analyzed to search for concordance in species distributions by using the program NDM/VNDM. Here, the traditional biogeographic hypothesis proposed for the region is evaluated for the first time by using a quantitative method and an optimal criterion specifically developed within the context of areas of endemism. Three different grid sizes (0.5° × 0.5°, 0.35° × 0.35 ° and 0.2° × 0.2°) were used to analyze three nested data sets: species found in the Andes of Argentina, Bolivia and/or Chile; Andean distributed species; and all grass species found in the study region. The main areas supported by the analyses correspond generally to the traditional biogeographic hypothesis proposed for the region. Local distribution patterns defined by species restricted to the study region were best supported under the small grid sizes, while the bigger grid sizes recovered areas defined by species with a broader distribution. The local distribution patterns emerged in all the analyses even when widespread species were added to the data set.

Parodiophyllochloa, a New Genus Segregated from Panicum (Paniceae, Poaceae) Based on Morphological and Molecular Data

Abstract Taxonomic features of species of Panicum, previously classified in section Cordovensia, subgenus Dichanthelium, of Panicum, are reviewed and compared with those of other taxa in the Paniceae. The new genus Parodiophyllochloa is proposed on the basis of ecological and morphological features (i.e. plants growing at the edge of forests, with membranous ligules, lower glume more than 1/2 the spikelet length, lower palea and lower flower absent, and upper anthecium indurate with simple papillae all over its surface) and chloroplast ndhF sequences to include six species ranging from Mexico to Argentina. The new combinations: Parodiophyllochloa cordovensis, P. missiona, P. ovulifera, P. pantricha, P. penicillata, and P. rhizogona are proposed. The new genus is compared with other genera of the Paniceae.

A PHYLOGENY OF SETARIA (POACEAE, PANICOIDEAE, PANICEAE) AND RELATED GENERA BASED ON THE CHLOROPLAST GENE ndhF

The genus Setaria is the largest genus in the so‐called bristle clade, a monophyletic group of panicoid grasses distinguished by the presence of sterile branches, or bristles, in their inflorescences. The clade includes both foxtail millet and pearl millet, the latter an important cereal crop in dry parts of the world. Other members of the clade are weeds that are widespread agricultural pests. Previous molecular phylogenetic studies have suggested that Setaria might not be monophyletic but did not have a large enough sample of species to test this rigorously. In addition, taxonomic studies have suggested a close relationship between Setaria and Paspalidium, with some authors combining them into a single genus, but molecular studies included too few Paspalidium accessions for a meaningful conclusion. Accordingly, we have produced 77 new sequences of the chloroplast gene ndhF for 52 species not in previous analyses. These were added to available sequences for 35 species in 10 genera of the bristle clade and four outgroup taxa. We find that Setaria species fall into several moderately to strongly supported clades that correlate with geography but not with the existing subgeneric classification. Relationships among these clades and among other genera within the bristle clade are unclear. Constraint experiments using the approximately unbiased test reject the monophyly of Pennisetum, Setaria, and Setaria plus Paspalidium, as well as several other groupings, although the test may be overly sensitive and prone to Type I error. The more conservative Shimodaira‐Hasegawa test fails to reject monophyly of any of the tested clades.

Phylogenetic Studies in the Paniceae (Poaceae) : a Realignment of Section Lorea of Panicum

Abstract The taxonomic status of Panicum section Lorea has remained as “incertae sedis” within Panicum. To resolve its position within the Paniceae and to test the monophyly of this section, phylogenetic analyses based on chloroplast sequence data (ndhF) and morphology were conducted for the Paniceae with particular emphasis on Panicum section Lorea. The results did not support the monophyly of this section. The species of this group were resolved in two clades which are not sister groups and neither of them is closely related to Panicum s.s. As a result, two new genera are proposed and described: Apochloa and Renvoizea, which are restricted to the Guiana highlands and eastern Brazil. New combinations are: Apochloa animara, A. bahiense, A. chnoodes, A. cipoense, A. eligulata, A. euprepes, A. jauana, A. lorea, A. lutzii, A. molinioides, A. poliophylla, A. sipapoense, A. steyermarkii, A. subtiramulosa, A. tijucae, Renvoizea acicularifolia, R. durifolia, R. glaziovii, R. lagostachya, R. marauense, R. restingae, R. sacciolepoides, R. teretifolia, R. trinii, and R. vaginiviscosa.

Phylogenetic Studies in the Paniceae (Poaceae-Panicoideae): Ocellochloa, a New Genus from the New World

Abstract The present contribution continues a critical revision of Panicum, particularly with the delimitation of “incertae sedis” taxa. A phylogenetic analysis of Paniceae based on cpDNA sequence data (ndhF) was performed with special emphasis on section Stolonifera of Panicum. Fourteen sequences of species of sect. Stolonifera and Echinolaena were added to a panicoid grass matrix previously published giving a total of 140 sequences. As a result, Ocellochloa is here described as a new genus including 12 new combinations: O. andreana, O. biglandularis, O. brachystachya, O. chapadensis, O. craterifera, O. irregularis, O. latissima, O. piauiensis, O. pulchella, O. rudis, O. soderstromii , and O. stolonifera. The position of Panicum venezuelae, previously placed in section Stolonifera with the above mentioned species, clearly indicates that this species is not closely related to the Ocellochloa clade. This conclusion is supported by several morphological characters, such as the presence of axillary inflorescences, cleistogamous spikelets, and glands of the lower lemma depressed, not crateriform. Ocellochloa differs from Panicum s. s. by the unilateral spikelet disposition, the smooth surface of the upper anthecium, and a C3 photosynthetic pathway. This new genus is described and compared with other allied genera of the Paniceae.