- Washington, District of Columbia, United States
Paul Peterson
Smithsonian Institution, Botany, Department Member
Based on morphological study and corroborated by unpublished molecular phylogenetic analyses, five grass species of high-mountain grasslands in Mexico, Central and South America, Agrostis bacillata, A. exserta, A. liebmannii, A. rosei,... more
Based on morphological study and corroborated by unpublished molecular phylogenetic analyses, five grass species of high-mountain grasslands in Mexico, Central and South America, Agrostis bacillata, A. exserta, A. liebmannii, A. rosei, and A. trichodes, are transferred to Podagrostis and bring the number of species of this genus recognized in the New World to ten. The name Apera liebmannii is lectotypified and epitypified. We provide an updated genus description for Podagrostis, and updated species descriptions, images, and notes on the new combinations. The diagnostic characteristics differentiating Podagrostis from Agrostis are: a) palea that reaches from (2/3) ¾ to almost the apex of the lemma; b) florets that usually almost equal the length of the glumes or are at least ¾ the length of the glumes; c) rachilla extension present and emerging from under the base of the palea as a slender short stub (rudimentary or up to 1.4 mm long, sometimes obscure in most florets in P. rosei), s...
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
A taxonomic treatment of 38 species of Muhlenbergia, a phylogeny based on analysis of six DNA sequence markers, and classification of Muhlenbergia for Central America (Belize, Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua,... more
A taxonomic treatment of 38 species of Muhlenbergia, a phylogeny based on analysis of six DNA sequence markers, and classification of Muhlenbergia for Central America (Belize, Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua, Panama; and Campeche, Chiapas, Quintana Roo, Tabasco, and Yucatán, México) is given. With the support from a molecular phylogeny we describe Muhlenbergia subg. Ramulosaesubgen. nov. In our treatment we place M. gigantea (younger name) as a synonym of M. mutica. Lectotypes are designated for the names Agrostis microsperma Lag., Epicampes gigantea E. Fourn., Lamarckia tenella DC., Muhlenbergia adspersa Trin., M. diversiglumis Trin., M. exilis E. Fourn., M. flabellata Mez, M. setarioides E. Fourn., Pereilema ciliatum E. Fourn., P. crinitum var. cirratum E. Fourn., Podosemum ciliatum Kunth, P. tenuissimum J. Presl, and Schellingia tenera Steud.
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Allolepis, Jouvea, Kalina, and Sohnsia are small (only Jouvea contains two species), often overlooked genera that are morphologically and genetically isolated within the tribe Cynodonteae. We present a molecular phylogeny using sequence... more
Allolepis, Jouvea, Kalina, and Sohnsia are small (only Jouvea contains two species), often overlooked genera that are morphologically and genetically isolated within the tribe Cynodonteae. We present a molecular phylogeny using sequence data from seven plastid markers (ccsA, ndhA intron, ndhF, rpl32-trnL, rpoC2, rps16-trnK, and rps16 intron) and the nuclear ribosomal internal transcribed spacer regions (ITS 1 & 2). Since Allolepis, Jouvea, Kalinia, and Sohnsia do not align within any of the 21 existing Cynodonteae subtribes, we describe Allolepiinae, Jouveinae, Kaliniinae, and Sohnsiinae as new. In addition, we provide descriptions, habitat, distribution, and comments for each subtribe.
Research Interests:
<p>Numbers above branches are maximum likelihood bootstrap/Bayesian posterior probability (MLBS/PP). Taxon labels are in the format: <i>Sorghum brachypodum</i>-2-Cowie8981-×2 where <i>Sorghum brachypodum</i>... more
<p>Numbers above branches are maximum likelihood bootstrap/Bayesian posterior probability (MLBS/PP). Taxon labels are in the format: <i>Sorghum brachypodum</i>-2-Cowie8981-×2 where <i>Sorghum brachypodum</i> indicates that the sequence belongs to the species <i>Sorghum brachypodum</i>; -2- = the second sequence listed in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0104933#pone.0104933.s004" target="_blank">Table S1</a> for the species; Cowie8981 = specimen voucher information; -×2 indicates we recovered 2 clones for the sequence; and without any mark after specimen voucher information indicates the sequence is derived from PCR-direct sequencing. Coloured taxon labels and circles correspond to the listed subgenera and geographic ranges at the top left corner of the figure, respectively.</p
Research Interests:
<p>Numbers above the branches are maximum likelihood bootstrap/Bayesian posterior probability (MLBS/PP). Taxon labels are in the format: <i>Sorghum almum</i>-Liu236 where <i>Sorghum almum</i> indicates that... more
<p>Numbers above the branches are maximum likelihood bootstrap/Bayesian posterior probability (MLBS/PP). Taxon labels are in the format: <i>Sorghum almum</i>-Liu236 where <i>Sorghum almum</i> indicates that the sequence belongs to the species <i>Sorghum almum</i>; -Liu236 = specimen voucher information. Coloured taxon labels and circles correspond to the listed subgenera and geographic ranges at the top left corner of the figure, respectively. Numbers 1–9 indicate the lineages of interest as shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0104933#pone-0104933-t004" target="_blank">Table 4</a>.</p
Research Interests:
Eleusine (Poaceae) is a small genus of the subfamily Chloridoideae exhibiting considerable morphological and ecological diversity in East Africa and the Americas. The interspecific phylogenetic relationships of Eleusine are investigated... more
Eleusine (Poaceae) is a small genus of the subfamily Chloridoideae exhibiting considerable morphological and ecological diversity in East Africa and the Americas. The interspecific phylogenetic relationships of Eleusine are investigated in order to identify its allotetraploid origin, and a chronogram is estimated to infer temporal relationships between palaeoenvironment changes and divergence of Eleusine in East Africa. Two low-copy nuclear (LCN) markers, Pepc4 and EF-1α, were analysed using parsimony, likelihood and Bayesian approaches. A chronogram of Eleusine was inferred from a combined data set of six plastid DNA markers (ndhA intron, ndhF, rps16-trnK, rps16 intron, rps3, and rpl32-trnL) using the Bayesian dating method. The monophyly of Eleusine is strongly supported by sequence data from two LCN markers. In the cpDNA phylogeny, three tetraploid species (E. africana, E. coracana and E. kigeziensis) share a common ancestor with the E. indica-E. tristachya clade, which is consid...
Research Interests:
To investigate the evolutionary relationships among species of the tribe Triraphideae (including two monotypic genera, Habrochloa and Nematopoa), we generated a phylogeny based on DNA sequences from nuclear ribosomal (ITS) and four... more
To investigate the evolutionary relationships among species of the tribe Triraphideae (including two monotypic genera, Habrochloa and Nematopoa), we generated a phylogeny based on DNA sequences from nuclear ribosomal (ITS) and four plastid markers (rps16-trnK, rps16 intron, rpl32-trnL, and ndhA intron). Habrochloa and Nematopoa form a clade that is sister to Neyraudia and Triraphis. Member of the Triraphideae have paniculate inflorescences, 3-veined, marginally ciliate lemmas, usually with hairy lateral veins, that are apically bifid and awned from between a sinus. A description of the Triraphideae and key to the genera is provided, and the biogeography is discussed, likely originating in Africa.
Research Interests:
Muhlenbergiaspatha, previously known only from near the type locality in San Luis Potosí, is reported from two localities in Zacatecas, Mexico. Historically, botanists have overlooked this diminutive annual. To clarify affinities of... more
Muhlenbergiaspatha, previously known only from near the type locality in San Luis Potosí, is reported from two localities in Zacatecas, Mexico. Historically, botanists have overlooked this diminutive annual. To clarify affinities of M.spatha, we present a molecular phylogeny emphasising species in M.subg.Pseudosporobolus using sequence data from two plastid markers (rpl32-trnL and rps16 intron) and nrDNA ITS. In addition, we include an updated description, illustration and discussion of the habitat of M.spatha.
Calamagrostis coahuilensis P.M. Peterson, Soreng & Valdes-Reyna, sp. nov., and Calamagrostis divaricata P. M. Peterson & Soreng, sp. nov, from Mexico are described and illustrated. Calamagrostis coahuilensis occurs on calcareous slopes in... more
Calamagrostis coahuilensis P.M. Peterson, Soreng & Valdes-Reyna, sp. nov., and Calamagrostis divaricata P. M. Peterson & Soreng, sp. nov, from Mexico are described and illustrated. Calamagrostis coahuilensis occurs on calcareous slopes in the mountains of southeastern Coahuila and southwestern Nuevo Leon; and C. divaricata occurs on moist slopes and mossy cliffs of southwestern Durango. Calamagrostis coahuilensisis morphologically similar to C. purpurascens but differs by having shorter anthers (1-1.2 mm long), nearly smooth ligules, scaberulous rachises, glabrous or minutely antrorsely scabrous sheath summits, and somewhat dense but not spikelike, greenish panicles. Calamagrostis divaricata seems morphologically allied to C. pringlei but differs by having wider panicles (4-10 cm) with branches reflexed spreading and divaricate, shorter spikelets (3.4-4.3 mm long), shorter glumes (3.4-4.3 mm long) that are both 1-veined, and shorter lemmas (3.8-4.3 mm long) with an awn inserted on u...
Research Interests:
A new Peruvian, high Andean, gynodioecious, cushion grass, Poa unispiculata, sp. nov. is described and illustrated. It is unique among all American species of Poa by having inflorescences composed of a single spikelet. It seems closely... more
A new Peruvian, high Andean, gynodioecious, cushion grass, Poa unispiculata, sp. nov. is described and illustrated. It is unique among all American species of Poa by having inflorescences composed of a single spikelet. It seems closely related to P. perligulata and differs by having a more compact habit, multiple equitantly distributed overlapping leaf sheaths with short distichous blades, presence of one spikelet per inflorescence, and gynodioecy with long anthers in bisexual plants.
Research Interests:
Agrostis lacuna-vernalis P.m. Peterson & Soreng, sp. nov., is described and illustrated. The new species occurs within or on the margins of vernal pools in monterey county, california and is known only from the former fort Ord Army... more
Agrostis lacuna-vernalis P.m. Peterson & Soreng, sp. nov., is described and illustrated. The new species occurs within or on the margins of vernal pools in monterey county, california and is known only from the former fort Ord Army military Base. The new species is morphologically similar to A. blasdalei but differs by having an annual habit, shorter glumes (1.5−2.4 mm versus 1.8−4 mm), shorter lemmas (1.1−1.5 mm versus 1.5−3 mm), and longer paleas (0.4−0.7 mm versus ±0.3 mm).
Research Interests:
The following four new combinations are made: Sporobolus borszczowii (Regel) P.M. Peterson, Sporobolus borszczowii subsp. acuminatus (Trin.) P.M. Peterson, Sporobolus borszczowii subsp. ambiguus (Boiss. & Balansa ex Boiss.) P.M. Peterson,... more
The following four new combinations are made: Sporobolus borszczowii (Regel) P.M. Peterson, Sporobolus borszczowii subsp. acuminatus (Trin.) P.M. Peterson, Sporobolus borszczowii subsp. ambiguus (Boiss. & Balansa ex Boiss.) P.M. Peterson, and Sporobolus montevidensis (Arechav.) P.M. Peterson & Saarela.
Research Interests:
Research Interests: Plant Biology and Biology
Research Interests:
Research Interests: Evolutionary Biology, Genetics, Geography, Biogeography, Historical Biogeography, and 15 morePhylogeny, Patagonia, Far East, New Zealand, New World, Molecular phylogenetics, North America, Northern Hemisphere, Asian American, Long Distance Dispersal, Mediterranean region, Divergence Time, Bayesian Estimator, Molecular Sequence Data, and Bayesian approach
Based on morphological and molecular evidence, Trisetum floribundum [syn. Dielsiochloa floribunda (Pilg.) Pilg.] is transferred to Festuca as Festuca floribunda (Pilg.) P.M. Peterson, Soreng & Romasch., comb. nov. Specimens examined... more
Based on morphological and molecular evidence, Trisetum floribundum [syn. Dielsiochloa floribunda (Pilg.) Pilg.] is transferred to Festuca as Festuca floribunda (Pilg.) P.M. Peterson, Soreng & Romasch., comb. nov. Specimens examined (Argentina, Bolivia, Chile, Peru) are included. Pilger (1906) described Trisetum floribundum based on two syntypes collected by A. Weberbauer [nos. 1028 & 2811] from Peru. Hitchcock (1927) effectively chose Weberbauer 1028 as a lectotype in his treatment of the Grasses of Ecuador, Peru, and Bolivia but did not cite a herbarium. Thirty-seven years later Pilger (1943) erected the new genus Dielsiochloa Pilg., with a single species [D. floribunda] and three varieties. He also stated that Weberbauer 1028 was “Typus der Art.” Pilger (1943, p. 100) mentioned that Deilsiochloa was roughly similar to species in Bromus sect. Stenobromus Griseb. (= Bromus sect. Genea Dumort., including B. sterilis L. and B. madritensis L.; see Soreng et al. 2018), in which the upp...
Research Interests:
Stancik, Daniel and Paul M. Peterson. A revision of Festuca (Poaceae: Loliinae) in South American paramos. Smithsonian Contributions from the United States National Herbarium, Volume 56, 184 pages (including 97 figures). A taxonomic... more
Stancik, Daniel and Paul M. Peterson. A revision of Festuca (Poaceae: Loliinae) in South American paramos. Smithsonian Contributions from the United States National Herbarium, Volume 56, 184 pages (including 97 figures). A taxonomic revision of Festuca L. for the South American paramos of Brazil, Colombia, Ecuador, northern Peru, and Venezuela is given. Fifty-six species and six subspecies of Festuca are recognized in the study area. Fifty-three species are native to the flora region and three are introduced and cultivated. Keys for determining the species, a classification, synonymies, descriptions, leaf anatomical descriptions, observations, distribution and habitat, specimens examined, illustrations, and leaf surface micrographs are provided. One species: F. turimiquirensis Stancik & P.M. Peterson, and one subspecies: F. tolucensis subsp. culata Stancik & P.M. Peterson, are newly described. The following three names were lectotypified: Bromus caldasii Kunth [=Festuca caldasii (Ku...
Research Interests:
Festuca aloha, sp. nov. of Kaua‘i and F. molokaiensis, sp. nov. from moloka‘i are described and illustrated. the two species are en demic to the hawaiian archipelago and grow on steep mountain slopes and volcanic cliffs with other native... more
Festuca aloha, sp. nov. of Kaua‘i and F. molokaiensis, sp. nov. from moloka‘i are described and illustrated. the two species are en demic to the hawaiian archipelago and grow on steep mountain slopes and volcanic cliffs with other native mesic flora. a key to the species of Festuca found in the h awaiian i slands is given.
Research Interests: Plant Biology and Biology
A molecular phylogenetic analysis based on plastid ( trnK-matK , matK, trnH-psbA, and trnL-trnF regions) and nuclear ITS DNA sequences of 68 species representing 11 genera suggests an entirely new hypothesis for the evolutionary history... more
A molecular phylogenetic analysis based on plastid ( trnK-matK , matK, trnH-psbA, and trnL-trnF regions) and nuclear ITS DNA sequences of 68 species representing 11 genera suggests an entirely new hypothesis for the evolutionary history within the tribe. Piptochaetium, Anatherostipa, Ptilagrostis and Hesperostipa are basal lineages that diverge independently from a clade that includes a monophyletic Jarava subg. Pappostipa (rendering Jarava s.l. polyphyletic) that is sister group to Austrostipa plus a subclade referred to as the "Major American Clade" (MAC). Within the MAC, New World Achnatherum is the sister group of a grade or clade of Jarava s.s. and a Nassella-Amelichloa clad e. Jarava subg. Pappostipa is monophyletic and not closely related to other sampled species of Jarava, supporting recognition of the new genus Pappostipa (Speg.) Romaschenko, RM. Peterson & Soreng with 23 species; Stipa speciosa selected as the lectotype. Within Pappostipa we identify two clades t...
Research Interests: Plant Biology and Biology
Bromus ayacuchensis, a new species from Departamento Ayacucho, Peru, is described and illustrated. The new species is similar to species in Bromus sect. Ceratochloa, particularly B. cebddilla, because of its strongly keeled lemmas. It... more
Bromus ayacuchensis, a new species from Departamento Ayacucho, Peru, is described and illustrated. The new species is similar to species in Bromus sect. Ceratochloa, particularly B. cebddilla, because of its strongly keeled lemmas. It differs from B. cebddilla by having densely pilose culms near the base, adaxially pilose ligules 3-6.6 mm long, lower glumes 1-veined, upper glumes 3-veined, pilose lemmas (especially along the margins and near the apex), lemma margins that are tightly involute on lower 1/5-1/4, and lemma awns 3-5.5 mm long. Phylogenetic analyses of sequence data from the internal transcribed spacer regions of nuclear ribosomal DNA place B. ayacuchensis in a clade with species of sect. Ceratochloa, whereas analyses of plastid data from the trnL intron and the 3'-end of ndhF indicate that B. ayacuchensis is closely related to this clade. Confirmed records are provided for B. modestus and B. cebadilla in Peru, and B. coloratus and B.flexuosus are reported for the fir...
Research Interests:
Calamagrostis coahuilensis P.M. Peterson, Soreng & Valdes-Reyna, sp. nov., and Calamagrostis divaricata P. M. Peterson & Soreng, sp. nov., from Mexico are described and illustrated. Calamagrostis coahuilensis occurs on calcareous slopes... more
Calamagrostis coahuilensis P.M. Peterson, Soreng & Valdes-Reyna, sp. nov., and Calamagrostis divaricata P. M. Peterson & Soreng, sp. nov., from Mexico are described and illustrated. Calamagrostis coahuilensis occurs on calcareous slopes in the mountains of southeastern Coahuila and southwestern Nuevo Leon; and C. divaricata occurs on moist slopes and mossy cliffs of southwestern Durango. Calamagrostis coahuilensis is morphologically similar to C. purpurascens but differs by having shorter anthers (1-1.2 mm long), nearly smooth ligules, scaberulous rachises, glabrous or minutely antrorsely scabrous sheath summits, and somewhat dense but not spikelike, greenish panicles. Calamagrostis divaricata seems morphologically allied to C. pringlei but differs by having wider panicles (4-10 cm) with branches ref lexed spreading and divaricate, shorter spikelets (3.4-4.3 mm long), shorter glumes (3.4-4.3 mm long) that are both 1-veined, and shorter lemmas (3.8-4.3 mm long) with an
Research Interests:
We conducted a molecular phylogenetic study of the subfamily Chloridoideae using six plastid DNA sequences (ndhA intron, ndhF, rps16-trnK, rps16 intron, rps3, and rpl32-trnL) and a single nuclear ITS DNA sequence. Our large original data... more
We conducted a molecular phylogenetic study of the subfamily Chloridoideae using six plastid DNA sequences (ndhA intron, ndhF, rps16-trnK, rps16 intron, rps3, and rpl32-trnL) and a single nuclear ITS DNA sequence. Our large original data set includes 246 species (17.3%) representing 95 genera (66%) of the grasses currently placed in the Chloridoideae. The maximum likelihood and Bayesian analysis of DNA sequences provides strong support for the monophyly of the Chloridoideae; followed by, in order of divergence: a Triraphideae clade with Neyraudia sister to Triraphis; an Eragrostideae clade with the Cotteinae (includes Cottea and Enneapogon) sister to the Uniolinae (includes Entoplocamia, Tetrachne, and Uniola), and a terminal Eragrostidinae clade of Ectrosia, Harpachne, and Psammagrostis embedded in a polyphyletic Eragrostis; a Zoysieae clade with Urochondra sister to a Zoysiinae (Zoysia) clade, and a terminal Sporobolinae clade that includes Spartina, Calamovilfa, Pogoneura, and Cr...
a taxonomic summary is presented for the colombian species of Eragrostis. The genus Eragrostis is represented in colombia by 25 species and one nontypical subspecies. Eragrostis mokensis pilg., E. nigricans (Kunth) steud., and E.... more
a taxonomic summary is presented for the colombian species of Eragrostis. The genus Eragrostis is represented in colombia by 25 species and one nontypical subspecies. Eragrostis mokensis pilg., E. nigricans (Kunth) steud., and E. rufescens schrad. ex schult. are reported for the first time in colombia. Keys for determining the species, descriptions, illustrations, geographical distributions, and morphological and ecological observations are provided for all native and adventive species of Eragrostis in colombia. Eragrostis patula (Kunth) steud. (= Poa patula Kunth) and E. unioloides (retz.) nees ex steud. (= Poa unioloides retz.) are excluded from the colombian Flora since all specimens identified as E. patula are apparently misidentified and are usually referable to Eragrostis tenuifolia (a. rich.) hochst. ex steud. a single specimen identified as Eragrostis unioloides as cited in the antioquia ś Flora was misidentified and is referable to Poidium juergensii (hack.) matthei.
Research Interests:
A taxonomie summary is presented for the Colombian species of Leptochloa. The classification, nomenclature, generic affinities, and morphological variation of the genus are discussed. Leptochloa is represented in Colombia by six species... more
A taxonomie summary is presented for the Colombian species of Leptochloa. The classification, nomenclature, generic affinities, and morphological variation of the genus are discussed. Leptochloa is represented in Colombia by six species and one nonty pical subspecies. Keys to recognize Colombian species are given, as well descriptions of the species, illustrations, geographical distributions, and morphological and ecological observations. The basionym Chloris dubia Kunth is lectotypified.
Research Interests: Plant Biology and Biology
The distributions of several narrowly endemic species of Poa in chile and argentina are discussed. Poa hachadoensis var. pilosa and P. mendocina are newly reported for chile. Poa pfisteri is described as a new species endemic to chile. a... more
The distributions of several narrowly endemic species of Poa in chile and argentina are discussed. Poa hachadoensis var. pilosa and P. mendocina are newly reported for chile. Poa pfisteri is described as a new species endemic to chile. a key to Nicoraepoa and Poa species (except species of Poa sect. Dioicopoa) that grow in chile from coquimbo southward is provided.
Research Interests:
Poa matri-occidentalis P.M. Peterson & Soreng, sp nov., is described and illustrated. Poa matri-occidentalis subsp. matri-occidentalis is known from steep rocky slopes of Cerro Gordo, Durango, and Poa matri-occidentalis subsp.... more
Poa matri-occidentalis P.M. Peterson & Soreng, sp nov., is described and illustrated. Poa matri-occidentalis subsp. matri-occidentalis is known from steep rocky slopes of Cerro Gordo, Durango, and Poa matri-occidentalis subsp. mohinorensis Soreng & P.M. Peterson, subsp. nov. is known from rocky cliffs of Cerro Mohinora, Chihuahua. The new species is morphologically similar to Poa kelloggii but differs by having leaf sheaths that are closed near the base 2/3 to 4/5 their length, entire ligules that are 3.5-6 mm long, nodding panicles, ovate lemmas with obtuse to acute apices, and non-visible rachilla internodes. A key distinguishing 11 species now reported from northern Mexico is provided.
Research Interests:
A taxonomic treatment of Trisetum Pers. and Grapitephorum Desv. in North America north of Mexico is given. Eight species of Trisetum are recognized. Two species are endemic to the United States: T. orthochaetum (Montana) and T. projectum... more
A taxonomic treatment of Trisetum Pers. and Grapitephorum Desv. in North America north of Mexico is given. Eight species of Trisetum are recognized. Two species are endemic to the United States: T. orthochaetum (Montana) and T. projectum (California, Montana, and Nevada); Trisetum cernuum subsp. cernuum, T cernuum subsp. canescens, T montanum, T. sihiricum, T. spicatum van spicatum, and T. spicatum van pilosiglume are found in Canada and the United States; and T. spicatum var spicatum and T. spicatum var pilosiglume are found in Greenland. Two species, T. aureum and T. Jlavescens, are introduced. Trisetum florihundum Pilg. is chosen as a lectotype for Trisetum sect. Aulacoa Louis-Marie. The genus Graphephorum comprises only two species: G. melicoides ranging from Canada to the United States and G. wo!/ii endemic to the United States. RESUMEN
Research Interests:
Herbarium study of Bromusgrandis, B. orcuttianus, and B. orcuttianus var. hallii from western North America has indicated that these taxa are morphologically and geographically distinct, and best treated as species. A new combination... more
Herbarium study of Bromusgrandis, B. orcuttianus, and B. orcuttianus var. hallii from western North America has indicated that these taxa are morphologically and geographically distinct, and best treated as species. A new combination Bromus hallii (Hitchc.) Saarela & P.M. Peterson is made. Bromus hallii differs from B. orcuttianus by having densely pubescent blades (verses glabrous in B. orcuttianus), lower sheaths with dense short stiff hairs 1 mm long or less (vs. long soft hairs 2-4 mm long), and l-2(-3) culm nodes (vs. 2-4). Bromus hallii differs from B. grandis by having blades that are 7.5-16.5 cm long [vs. (13-)18-38 cm long in B. grandis], l-2(-3) culm nodes (vs. 3-7), and lower glumes that are l(-3)-nerved [vs. 3(l)-nerved], We provide the first report of differences in the type of pubescence on the lower sheaths between B. orcuttianus and B. hallii. We confirm the diploid chromosome number of 2n 14 for B. grandis. We include descriptions, synonymies, and representative spe...
Research Interests: Plant Biology and Biology
Accepted names, common names, and widely used synonyms for 347 species of grasses found in Maryland are reported. We provide information on their frequency, distribution, and conservation status.
Research Interests:
Ptilagrostis luquensis P.M. Peterson, Soreng & Z.L. Wu from the People's Republic of China is described and illustrated. The new species was found in dense thatch, mollisol soils on nearly level grassy plains surrounded by low hills... more
Ptilagrostis luquensis P.M. Peterson, Soreng & Z.L. Wu from the People's Republic of China is described and illustrated. The new species was found in dense thatch, mollisol soils on nearly level grassy plains surrounded by low hills in Gansu Province. Ptilagrostis luquensis is morphologically similar to P. dichotoma but differs by having glabrous anthers (1-1.4 mm long), shorter spikelets (2.6-3.5 mm long), shorter glumes (2.6-3.5 mm long), shorter lemmas (2.2-2.7 mm long), shorter and narrower panicles (2-5.2 x 1-3 cm), and lower nodes with 1 or 2 sheathing lanceolate hyaline bracts (1-5 mm long) on the culm inserted immediately below the lowest branches. A key to the species of Pti lagrostis in China is provided. M 1c (CHINESE ABSTRACT) *3tfiai£7Xl=i+ [!£$•W'H'SaM^^it-Ptilagrostis luquensis P.M. Peterson, Soreng & Z.L, Wu. iSDfWJRfitfittSSiair, ^KffidjlWiftW^liJTCM'K M ffiSBW^ Ptilagrostis luquensis ^«XS]ffi#/. dichotoma lr~.3M.±MM, iS.\K»\ ffi-f ftMttittM, -fcl-1....
Research Interests:
A new species, Poa ramifer Soreng & P.M. Peterson, from Ancash, Peru is described and illustrated. It differs from all other American species of Poa in having erect, aerially branching culms with lateral shoots that persist and flower in... more
A new species, Poa ramifer Soreng & P.M. Peterson, from Ancash, Peru is described and illustrated. It differs from all other American species of Poa in having erect, aerially branching culms with lateral shoots that persist and flower in subsequent seasons. The spikelets of the gynomonoecious plants have proximal perfect and distal pistillate florets with dimorphic lodicules.
Research Interests:
A taxonomic treatment of the subtribe Muhlenbergiinae for northeastern Mexico (Coahuila, Nuevo Leon, and Tamaulipas) is given. A total of 39 native species are recognized in the study area in four genera: Aegopogon (1), Blepharoneuron... more
A taxonomic treatment of the subtribe Muhlenbergiinae for northeastern Mexico (Coahuila, Nuevo Leon, and Tamaulipas) is given. A total of 39 native species are recognized in the study area in four genera: Aegopogon (1), Blepharoneuron (1), Lycurus (2), and Muhlenbergia (35). The names, Muhlenbergia glomerata var. ramosa Vasey and Muhlenbergia spiciformis Trim, are lectotypified. A key for determining the species, descriptions, distributions, specimens examined, illustrations, synonymies, and a brief discussion indicating relationships among all species of Muhlenbergia in northeastern Mexico are provided.