Blandy Experimental Farm Research Articles

The influence of conopid flies on bumble bee colony productivity under different food resource conditions

AbstractFloral resources and natural enemies are considered important drivers of wild bee population dynamics, yet there is little information on how these factors, either independently or in combination, influence the demographic performance of bees. Bumble bees (Bombus spp.), ecologically important social insects, have long colony cycles lasting many weeks. Food shortfalls during the colony lifetime can result in smaller colony sizes and lower reproductive output. Conopid flies (Conopidae, Diptera) are prevalent endoparasitoids of bumble bees, often infecting high percentages of free‐flying individuals. Conopids can reduce worker life span and foraging efficiency; consequently, they may negatively affect colony success. In this study, we evaluated how seasonal variability in food resources and conopid parasitism together influence the productivity of bumble bee colonies through construction of a simulation model. In addition to simulating colony performance in relation to a defined food environment and conopid‐induced worker mortality, we evaluated how daily background mortality risk and the timing of colony initiation affected growth and reproductive outcomes of colonies, as well as the degree of influence exerted by conopids. Model parameters were largely informed by field data collected from Bombus impatiens colonies at our study site (Blandy Experimental Farm, Boyce, Virginia, USA), including data on forager risk of conopid parasitism as assessed using radio‐frequency identification (RFID) technology. In spite of the high probability of parasitism (4% per hour of flight during seasonal peak) incorporated into our model simulations, lethal parasitism by conopids generally had a modest influence on colony productivity, reducing reproductive output by 15% or less across most tested scenarios. However, conopids were more influential under very low resource conditions, reducing reproductive output by 21–28%. Inclusion of sublethal effects of conopids on foraging activity further reduced colony performance in all scenarios, but had a greater impact on colony performance under the poorest resource conditions. This work emphasizes that the importance of natural enemies to the demographic performance of bees can increase under certain environmental conditions and highlights the value of using models to consider multiple stressors that are difficult to evaluate simultaneously in field experiments.

Correlating species and spectral diversities using hyperspectral remote sensing in early-successional fields.

Advances in remote sensing technology can help estimate biodiversity at large spatial extents. To assess whether we could use hyperspectral visible near‐infrared (VNIR) spectra to estimate species diversity, we examined the correlations between species diversity and spectral diversity in early‐successional abandoned agricultural fields in the Ridge and Valley ecoregion of north‐central Virginia at the Blandy Experimental Farm. We established plant community plots and collected vegetation surveys and ground‐level hyperspectral data from 350 to 1,025 nm wavelengths. We related spectral diversity (standard deviations across spectra) with species diversity (Shannon–Weiner index) and evaluated whether these correlations differed among spectral regions throughout the visible and near‐infrared wavelength regions, and across different spectral transformation techniques. We found positive correlations in the visible regions using band depth data, positive correlations in the near‐infrared region using first derivatives of spectra, and weak to no correlations in the red‐edge region using either of the two spectral transformation techniques. To investigate the role of pigment variability in these correlations, we estimated chlorophyll, carotenoid, and anthocyanin concentrations of five dominant species in the plots using spectral vegetation indices. Although interspecific variability in pigment levels exceeded intraspecific variability, chlorophyll was more varied within species than carotenoids and anthocyanins, contributing to the lack of correlation between species diversity and spectral diversity in the red‐edge region. Interspecific differences in pigment levels, however, made it possible to differentiate these species remotely, contributing to the species‐spectral diversity correlations. VNIR spectra can be used to estimate species diversity, but the relationships depend on the spectral region examined and the spectral transformation technique used.

Identifying invasive plant species using field spectroscopy in the VNIR region in successional systems of north-central Virginia

ABSTRACTRemote sensing can potentially be used to monitor the extent and distribution of invasive species across landscapes and regions, thus aiding conservation efforts. We collected ground-level hyperspectral data of six exotic invasive plant species in abandoned agricultural fields at the Blandy Experimental Farm in northern Virginia to determine the degree to which species could be identified using visible and near-infrared wavelengths. The spectral profile from 350 to 1025 nm was used in support vector machine analysis to determine separability of these species. We used sensitivity analyses to determine which spectral regions were most influential to identifying species by removing 50 nm regions and comparing species identification to that using the full spectral profile. Ailanthus altissima, Carduus acanthoides, and Cirsium arvense had high ability to be identified (75%, 87.5%, and 75%, respectively). Galium verum had low ability to be identified (44.4%), perhaps due to high spectral contamination from soil. Celastrus orbiculatus and Rhamnus davurica had low ability to be identified (27.3% and 30.8%, respectively); however, they were often misclassified as each other, due to their physical overlap in the field. The sensitivity analysis revealed that the 350–399, 500–549, 700–749, and 900–949 nm regions were most useful for species identification, while 550–599 and 650–699 nm regions were detrimental, perhaps due to greater intraspecific variability than interspecific variability in these regions. These most influential regions for identification were similar to those found in other studies. Thus, it is possible to identify species using ground-level hyperspectral data.

Niche Overlap and Diet Breadth: Can bumble bee (Bombus spp.) foraging behavior reveal species vulnerabilities?

Within the last two decades, notable shifts have taken place within the bumble bee (Bombus spp.) communities of North America: some species have experienced substantial, rapid declines, while others appear to be stable or even experiencing range expansion. Studies from the UK and Europe implicate the loss of natural habitat and associated floral resources in overall bumble bee declines and species losses. Research also indicates that loss of host plants disproportionately impacts species with narrower diet breadths, and that these species are more likely to be long-tongued (presumably due to the reduction of long-tubed floral hosts). In contrast, species with more generalized diets have been shown to be more abundant. In this study we examined resource utilization by the bumble bee community at Blandy Experimental Farm in Boyce, VA in order to evaluate (1) whether the diet of a potentially declining long-tongued species (B. fervidus) overlaps strongly with a more competitive, expanding species (B. impatiens), (2) whether the potentially declining species specializes on host plants relative to the other bumble bee species in the community, and (3) if bumble bee species abundance is associated with diet breadth or the relative abundance of preferred host plants. We surveyed and quantified all mass flowering species in two large meadows on a weekly basis from June 1 to August 15, 2010. Collections of bees were then carried out on these plants for a minimum of one person-hour per week per plant species. For each bee species, Simpson’s index was used to assess diet breadth.Six bumble bee species were observed at Blandy Experimental Farm in total. The potentially declining and expanding species (B. fervidus and B. impatiens) possessed the narrowest and widest diet breadths respectively. In addition to possessing specialist tendencies, B. fervidus had little niche overlap with other species in the community (i.e. it visited plants other species were not visiting). Although B. impatiens had the widest diet breadth and was also the most abundant species (50% total collections), diet breadth, overall, was not associated with abundance (Spearman’s rho = 0.37, p = 0.46). However, we found that species abundance was positively correlated with abundance of most preferred host plant (Spearman’s rho = 0.97, p = 0.0012). The results of this study indicate that resource limitation may put B. fervidus at risk of decline when preferred host plants are reduced or lost, whereas B. impatiens may be resistant to extirpation due to its “super-generalist” tendencies.

Ecological mentoring: inspiring future scientists

Is nature obsolete? This year, the publisher of the Oxford Junior Dictionary decided to replace dozens of nature-related words, such as “beaver” and “dandelion”, with [words like] “blog” and “MP3 player”. Children just aren't going outside much anymore (Richard Louv, San Diego Times, 24 Feb 2009; author, Last child in the woods) For the past 200 years, Americans have endeavored to improve the quality of life for the next generation. Our country is finally waking up to the realization that this legacy is measured not only in bank accounts, but is also reflected in the quality of our natural capital. Raising the quality of life for children has been an attainable component of the “American dream” for at least six generations, but this goal is now in jeopardy. A “green” stimulus package is in order for America. If individuals, families, and schools returned to nature-based recreation in these times of fiscal restraint, such outdoor activities could enhance science education, ease household budgets, and send a strong message to advocate conservation of natural areas (which, in turn, would contribute to the protection of cost-saving ecosystem services to society). Professional ecologists can lead the charge, engaging teachers and children in our communities. The theme of ESA's 2008 Annual Meeting in Milwaukee centered on ecology education, and included the Society's first daylong workshop that featured ecologists mentoring local K–12 science teachers. Afterwards, ESA's Education and Human Resources Committee issued a challenge to the Society's members: the institution of a program that would aim for “no child left indoors” by the year 2015. To that end, we encouraged members to offer community outreach activities in ecology; for example, if each of our 10 000-strong membership of ecologists spoke to 100 open-minded citizens every year over 10 years, approximately 10 million people could learn from a professional ecologist. If some of those citizens were K–12 science teachers, then the audience might even double or triple. Since that original challenge was issued, an increasing number of ecology education outreach activities have been initiated by the ESA education section, including a summer nature camp at Blandy Experimental Farm in Virginia, ecosystem quilt-making for elementary kids in Florida, ecology field trips for juvenile offenders in Minnesota, the mapping of invasive plants by citizen scientists in North Carolina, forest canopy field trips for middle schools via satellite technology, and many others. For professional ecologists who wish to become scientist citizens in their own community, one “low-hanging fruit” would be to mentor a local K–12 teacher. This relationship can have enormous trickle-down effects on hundreds of students, as well as on their parents and neighbors. The authors of this editorial have shared a mentoring partnership for over 15 years, mutually enhancing our research and teaching skillsets. As a consequence of mentoring, one of us (DCR) participated in field research, coauthored papers in scientific journals, and consequently brought an enthusiasm for science back to the classroom that has inspired hundreds of high-school students. The other (ML) shifted part of her professional focus to K–12 ecology education that included distance-learning programs and leading field trips to the Amazon for at-risk teenagers, thanks to insights gained by mentoring a high-school science teacher. In 2010, ESA will host an education summit – entitled What will ecology education look like in 2020? –embracing three goals: (1) to assemble diverse national organizations that undertake ecology education, to share their best practices for nature-based learning and thus avoid redundancy in our efforts; (2) to create “one voice” for important issues in ecology education, such as the promotion of ecological literacy and better stewardship of ecosystem health; and (3) to spotlight some of the recent, transformational advances in ecology education (such as the National Ecological Observatory Network and Long Term Ecological Research programs, “no child left indoors”, gaming simulations, and new curricula). The summit will serve ESA's long-term objectives of producing a future supply of effective ecologists, enhancing diversity, informing policy, and raising ecological literacy for both citizens and practitioners. America not only needs excellent ecological research, but also outstanding ecological education. As professional ecologists, we hope that all ESA members will engage as scientist citizens and offer outreach activities that will inspire their communities, with a special focus on mentoring K–12 teachers in local school districts who, in turn, will positively impact hundreds of young people.

Foliar δ15N patterns along successional gradients at plant community and species levels

Relationships to 15N abundances have been found in aridity, rainfall, soil age and latitudinal gradients across large spatial and temporal scales and patterns at intermediate spatial and temporal scale remain unclear. An investigation on 15N abundances at intermediate spatial and temporal scale was conducted in a series of successional fields (Blandy Experimental Farm) in northern Virginia. Foliar and soil samples were collected from these fields in mid‐summer 2004 and 2005. The results showed that foliar δ15N signatures decreased as successional age increased at both the plant community and species levels. There were also significant decreases in soil δ15N as succession proceeded. These results provide a clear example that δ15N signatures in certain ecosystems, like an early successional field, could change significantly at time scales within human lifespans and such dynamics should be considered when modeling δ15N spatial patterns.

A Comparison of Pan Trap and Intensive Net Sampling Techniques for Documenting a Bee (Hymenoptera: Apiformes) Fauna

Recent interest in pollinator sampling, often motivated by concerns about pollinator decline, has led to the increased use of standardized sampling protocols based on passive insect traps. Compared with netting insects at host plants, these protocols have the potential to limit some types of sampling bias, such as those associated with a researcher's observational and netting skills. The most commonly deployed recent protocol is the use of colored pan traps (bowls) filled with soapy water (Aguiar and Sharkov, 1997; Calbuig, 2001; Cane et al, 2000; Leong and Thorp, 1999; Toler et al, 2005). Insects approach the bowls, land on the water, and drown. The method is particularly good at catching numerous species of bees, but can also be effective for capturing various flower-visiting flies, skippers and a wide range of other insect taxa. As a bee sampling device, pan traps have several known biases: they catch bumble bees, honey bees and bees in the genus Colletes much less frequently than expected by their perceived abundance (e.g., Toler et al, 2005). Pan traps are especially good at catching halictid bees (Family Halictidae). Because of these biases, researchers sometimes use a modest amount of net collecting on flowers to accompany pan traps. Other potential biases remain to be studied, such as whether the effectiveness of pan traps is inversely related to flower abundance, a bias suspected by several researchers but not yet studied. Based on their pan-trapping study, Toler et al (2005) concluded that the predominant flower color in the plant community did not influence the relative attractiveness of particular pan trap colors, but they did not study the effect of floral abundance per se. Depending on a researcher's interest in deploying pan traps, these biases may or may not generate concern. Pan traps seem very well suited to testing for the presence of particular bee species in the community (Leong and Thorp, 1999), including many parasitic bee species that are seldom caught at flowers. They also provide a very valuable tool for augmenting other collecting methods, especially when there are few host plants to sample (e.g., early spring). Work by Cane et al. (2000) included a comparison of pan traps versus intensive netting to sample the very diverse and well known flower-visiting insect fauna of creosote bush. These workers concluded that pan trapping was of limited use in detecting the creosote bush fauna because of numerous species caught by netting but not by pan traps. Pan traps did catch many bee species not netted at creosote bush, however. Because netting in that study was restricted to creosote bush, there was no basis to compare the relative effectiveness of netting versus pan trapping for sampling a local bee fauna in the wider flower-rich community. In 2002 in northern Virginia, we carried out an intensive netting/observational survey of floral visitors within one hectare plots at Blandy Experimental Farm, an ecological experiment station of the University of Virginia. The sampled habitat was an open field and the sampling protocol comprised net sampling on the six most prominent plant species in the community from 8:00-16:00 hrs Eastern Daylight Time. Each plant species was surveyed for a total of 2.25 hrs, spread equally across the sampling period. Each of three researchers sampled all plant species in succession, one species at a time, three times across the sampling period (8:00-10:00, 11:00-13:00, 14:00-16:00). Survey periods lasted 15 mins per plant species per researcher, with researchers moving through the entire plot during that period. Bee species that could be recognized on the wing (e.g., Apis mellifera) were noted but not captured. To compare the effectiveness of pan trapping to such an intensive netting protocol at one of our sites, we placed a line of 30 pan traps (6 oz Solo bowls painted fluorescent blue, fluorescent yellow, or left white) in a diagonal line across the plot,

Walter Samuel Flory Jr.

Walter S. Flory Jr., Babcock Professor Emeritus at Wake Forest University, was born on 5 October 1907 in Bridgewater, Virginia, and died on 8 June 1998 at the age of 90, in Winston-Salem, North Carolina. Walter was an outstanding student. After graduating from Bridgewater College in 1928, he entered the University of Virginia as a Blandy Fellow. He earned an M.A. (1929) under William A. Kepner in one year and a Ph.D. in Biology (1931) under Orland E. White in another two years, at the age of 23. He enjoyed a year of postdoctoral work (1935-1936) under E. M. East and Karl Sax at Harvard as a National Fellow and Research Associate in Biological Science. He was elected to Phi Beta Kappa, Phi Sigma, Tau Kappa Alpha, and Sigma Xi. Dr. Flory was an outstanding geneticist, botanist, and educator. He served with distinction at several institutions: 1931-1932, in charge of Technical Work for Shaver Bros., Inc.; 1932-1934, Instructor of Science at Greenbriar Junior College; 19341935, Professor of Biology at Bridgewater College; 1936-1944, Horticulturist at Texas Agricultural Experimental Station (Texas AM 1944-1947, Horticulturist at Virginia Agricultural Experimental Station (Virginia Polytechnic Institute); 19451948, Collaborator with the U.S. Department of Agriculture; 1947-1963, Professor of Experimental Horticulture at University of Virginia (President and Visitors Research Prize recipient, 1951), and Vice Director and Manager of the Blandy Experimental Farm; 1955-1963, Curator of the 0. E. White Research Arboretum; 1964-1976, Director of Reynolda Gardens; 1969-1972, President of Highlands Biological Station; 1972, Research Consultant for Fairchild Tropical Garden; and 1963-1980, Babcock Professor of Botany at Wake Forest University. Professor Flory contributed significantly to many professional organizations: the Association of Southeastern Biologists (Executive Committee member, 1956-1959; Vice President, 1960-1961; President, 1962-1963; ASB Research Prize recipient, 1978; and wrote A 50-Year Historical Perspective 1937-1987 of the Association of Southeastern Biologists for its 50th anniversary); American Association of Botanical Gardens and Arboretums (Editorial Board, 1962-1964); American Boxwood Society (Cofounder, Treasurer, Editor, Director, 1961-1963); American Magnolia Society (Vice President, 1968-1974); Botanical Society of America (Chairman, Southeastern Section, 1951-1952); Southern Appalachian Botanical Club (Vice President, 1962); and the Virginia Academy of Science (President, 1956; J. Shelton Horsley Research Award recipient, 1949; and wrote History of the Virginia Academy of Science for its 50th anniversary in 1973). Dr. Flory's involvement and recognition exceeded national boundaries. He was a delegate to the International Botanical Congresses in Paris (1954), in Montreal (1959), in Edinburgh (1964), in Seattle (1969), and in Sydney (1981). He was a member of the International Genetics Congress in Montreal (1958) and in Tokyo (1968). He was a member of the International Horticultural Congress in College Park, Maryland (1966), and in Sydney, Australia (1978). He was an invited lecturer at the International Seminar on Chromosomes in Calcutta (1968, 1976). He was also honored as a Bicentennial Fellow of the Royal Horticultural Society. An area of special interest to Dr. Flory was the cytotaxonomy of the Amaryllidaceae. He developed this interest as a horticultural geneticist for the Texas Agricultural

INHERITANCE OF RED HAIR FOR SIX GENERATIONS

Journal Article INHERITANCE OF RED HAIR FOR SIX GENERATIONS Get access W. RALPH SINGLETON, W. RALPH SINGLETON Search for other works by this author on: Oxford Academic PubMed Google Scholar BRENDA ELLIS BRENDA ELLIS *Blandy Experimental Farm, University of VirginiaBoyce and Bowman Gray School of MedicineWinston-Salem, North Carolina Search for other works by this author on: Oxford Academic PubMed Google Scholar Journal of Heredity, Volume 55, Issue 6, November 1964, Page 261, https://doi.org/10.1093/oxfordjournals.jhered.a107345 Published: 01 November 1964

COAT COLOR IN CARABAOS OF THE PHILIPPINES

Journal Article COAT COLOR IN CARABAOS OF THE PHILIPPINES Get access W. RALPH SINGLETON, W. RALPH SINGLETON Search for other works by this author on: Oxford Academic PubMed Google Scholar IBARRA SANTOS IBARRA SANTOS *Director of Blandy Experimental Farm, University of Virginia, Boyce, and consultant in 1963 to the Atomic Energy Commission of the Philippines, Manila; and Research Associate, Philippines Atomic Research Center, Quezon City, Philippines, respectively. The Philippine carabao census figure was obtained through the courtesy of the Division of Agriculture and National Resources of Manila, The Philippines. Search for other works by this author on: Oxford Academic PubMed Google Scholar Journal of Heredity, Volume 55, Issue 4, July 1964, Pages 159–162, https://doi.org/10.1093/oxfordjournals.jhered.a107321 Published: 01 July 1964

Chromosome Numbers in the Rutaceae

ORIGINAL chromosome counts for three members of the subfamily Rutoideae of the family Rutaceae are given as follows. Correa backhousiana has n = 16, in agreement with the counts for three other species of Correa found by Smith-White1. Evodia danielli has n = 40, this count differing from that found by Bowden2, who gives n = 36 for material grown on the Blandy Experimental Farm, University of Virginia. My material, originally obtained from North China, is now growing in the Royal Botanic Gardens, Kew. Its chromosome number suggests aneuploidy. It is interesting to note the apparent existence of chromosome races within the species Evodia danielli. Choisya ternata has n = 27—a first count for the genus.

CYTOTAXONOMIC OBSERVATIONS ON SOME GENERA OF THE SOLANAE: MARGARANTHUS, SARACHA, AND QUINCULA

American Journal of BotanyVolume 37, Issue 1 p. 25-30 Article CYTOTAXONOMIC OBSERVATIONS ON SOME GENERA OF THE SOLANAE: MARGARANTHUS, SARACHA, AND QUINCULA Margaret Young Menzel, Margaret Young Menzel Blandy Experimental Farm, University of Virginia, Boyce, VirginiaSearch for more papers by this author Margaret Young Menzel, Margaret Young Menzel Blandy Experimental Farm, University of Virginia, Boyce, VirginiaSearch for more papers by this author First published: 01 January 1950 https://doi.org/10.1002/j.1537-2197.1950.tb08157.xCitations: 11AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume37, Issue1January 1950Pages 25-30 RelatedInformation

INITIATION AND DEVELOPMENT OF THE GALL OF AYLAX GLECHOMAE ON NEPETA HEDERACEA

THE PROBLEM of cell growth and its control is of major importance in biological research today. Galls offer an excellent opportunity for study of abnormal tissue initiation and growth both because of their abundance and the comparative simplicity of the tissues involved. European botanists in the latter part of the 19th century catalogued and observed galls and gall-makers and made a few anatomical studies of galls. Relatively little research on galls has been carried on since the turn of the century. Gall studies need reinterpretation and further investigation in the light of more recent developments in the fields of anatomy, cytology, and physiology. Toward this end the present study undertakes to determine how -gall growth takes place, how normal leaf cells compare with gall cells, and if possible, the nature of the stimulus for gall formation. The gall of Nepeta hederacea was selected for study because normal leaf growth is relatively simple with only primary tissues involved except in major veins. MATERIALS AND METHODS.-Materials were collected near Roanoke, Virginia, in Charlottesville, Virginia, and at Blandy Experimental Farm near Boyce, Virginia. Seventy stem apices and over sixty galls of graduated size were fixed in formalinacetic-alcohol for 18-24 hr., or in Randolph's modification of Navas'hin for 12 hr. Galls to be tested for ribose nucleic acid were fixed in Helly's mixture (Lee, 1937) for 12 hr. and later treated with iodine alcohol. The stem apices and galls were dehydrated and cleared in ethyl alcohol and chloroform respectively, after which they were embedded in a 1 :1 paraflin-Tissuemat combination. Stem apices were sectioned at 7 and at 12 /, either longitudinally or transversely. 'Galls were cut at 7 and at 12 I, longitudinally, transversely, or paradermally. For general anatomical study most of the sectioned material was stained with safranin-fast green or safranin-anilin blue using tannic acid mordant. Photomicrographs were made in most cases from slides stained with safranin-anilin blue. Sectioned material for nuclear observations was stained by the Feulgen reaction. Tissues fixed in Helly's mixture to be tested for ribose nucleic acid were treated with ribonuclease.2 Twenty slides were placed in distilled water con-

Studies in the Leguminosae. I. Chromosome Numbers in Erythrina L.

American Journal of BotanyVolume 34, Issue 8 p. 407-414 Article STUDIES IN THE LEGUMINOSAE. I. CHROMOSOME NUMBERS IN ERYTHRINA L. Earlene Atchison, Earlene Atchison The Blandy Experimental Farm, University of Virginia, Boyce, VirginiaSearch for more papers by this author Earlene Atchison, Earlene Atchison The Blandy Experimental Farm, University of Virginia, Boyce, VirginiaSearch for more papers by this author First published: 01 October 1947 https://doi.org/10.1002/j.1537-2197.1947.tb13009.xCitations: 5AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume34, Issue8October 1947Pages 407-414 RelatedInformation

CHROMOSOME NUMBERS IN THE MYRTACEAE

THE MYRTACEAE have received comparatively little cytological attention, partly because of technical difficulties, and partly because the majority of species are relatively far removed from the centers of intensive study. Cytology in its more recent developments has proved its value in clarifving some of the problems of phylogeny, and it appeared likely that it might provide support for chemical, geographical and geological observations on the Myrtaceae. Neidenzu, in Die Naturlichen Pflanzenfamilien (1898), attributes 2750 species of tropical and warm temperate shrubs and trees to the Mvrtaceae. Andrews (1913) considered the family as consisting of approximately 3100 species. family falls naturally into two subfamilies, the primarily fleshyfruited Myrtoideae with thirty-two genera of worldwide tropical distribution, and the capsular-fruited Leptospermoideae with forty genera. best known species of Myrtoideae, Myrtus communis, is cultivated in Europe, although native to western Asia. With the exception of a monotypic genus in Chile, Tepualia, and extensions of Backhousia and Baeckea into Asia and Africa, the Leptospermoideae are largely limited to the Australasian region. Numerous ornamentals are found in both subfamilies. Eucalyptus, containing over 600 species and varieties (Blakely, 1934; 230 species, Willis, 1925), is an important source of fast-growing, durable woods and aromatic oils. Allspice is obtained from Pimenta; the guava from Psidium; and cloves from Eugenia. Studies of the Myrtaceae have been concentrated in Australia, and are, therefore, concerned mainly with the Leptosperinoideae. Difficulties imposed by intraspecific variation and interspecific hybridization are particulaarly apparent in taxonomic treatments of Eucalyptus (von Mueller, 1879-1884; Maiden, 1909-1929; Blakely, 1934). Analyses of the essential oils (Baker and Smith, 1902, 1920; Penfold and Morrison, 1927, 1932, 1934; McNair, 1942) have in the opinion of some workers established more reliable criteria for the delimitation of species, hybrids and varieties than strict morphological investigations. Summarizing the chemical analyses in their relation to the phylogeny of Eucalyptus, McNair states: There has been orderly evolution in volatile oil characteristics of the Eucalypti which may be correlated with changes in morphological characteristics. However, oil groups represent cross-sections of the phylogenetic tree and not necessarily genetic sequences or natural groups of the systematist. Botanically distinct species are generally distinguished by their chemical constituents and also in some cases where. morphological examinations show little or no difference, chemical 1 Received for publication October 19, 1946. analysis of the oil reveals the existence of completely distinct varieties. Cytological contributions have dealt mainly witlh the Leptospermoideae. McAulay and Cruickshank (1937) described microspore development in-Eucalyptus. Smith-White (1942) studied meiosis in six genera-Angophora, Eucalyptus, Tristania, Backhousia, Leptospermum and Callistemon. Reports of chromosome numbers are found in various other papers (table 1). MATERIALS AND METHODS.-Chromosome counts were made for two genera-Psidium and Eucalyptus. Plants were obtained chiefly from the Division of Plant Introduction and Exploration, Department of Agriculture, and from Theodore Payne, Los Angeles, California, and were grown in a greenhouse at Blandy Experimental Farm. Although Psidium produced fruit freely in the greenhouse, no Eucalyptus flowered. Herbarium specimens have been deposited in the Bailey Hortorium; specimen number is included in table 1. All counts were made from smears of young leaves stained with acetic orcein. Camera lucida drawings were made at a magnification of ca. 5000 and reduced in reproduction to ca. 3350. Previously reported chromosome numbers in the Myrtaceae as well as those from this study have been listed in table 1. General distribution of the various genera and the source of the plants are also included. generic sequence followed is that of Neidenzu (1898); Blakely's Key to the Eucalypts (1934) was used in an attempt to reduce the synonymy among Eucalyptus collections although the species are listed in the table as they were named at the source. Species of Psidium are also listed as received; the only doubtful species is P. variabile which is probably a horticultural form of P. cattleianum. OBSERVATIONS.-Twenty-three Eucalyptus species were found to have a 2n number of 22. Two species, E. corynocalyx and E. redunca, are apparently aneuploids with 2n = 24; these are the only exceptions to 2n = 22 thus far reported among the Leptospermoideae. A similar constancy did not occur in Psidium: P. guajava has 2n = 22; P. cattleianum and P. cattleianum var. lucidum have 2n _88, which is to be considered an octoploid number. chromosomes are small in both Psidium and Eucalyptus, ranging from approximately 1.22.5 ts. Although satellites and constrictions could occasionally be located, the leaf smear technique did not permit significant morphological study. DIscussIoN.-The Myrtaceae are, on the basis of the species thus far studied, an unlikely subject for intensive use of cytotaxonomic methods. Anderson (1937) has stressed the definite limitation on the use of chromosome number as a relationship criterion: The taxonomic usefulness of information

British Council Science Office in China : Dr. R. A. Silow

DR. R. A. SILOW, until recently scientific officer of the Agricultural Research Council at the Plant Breeding Institute, Cambridge, has been appointed director of the British Council's Science Office in China, in succession to Dr. Joseph Needham, who is now with the United Nations Educational, Scientific and Cultural Organisation. Dr. Silow is a graduate of the University of Reading in agricultural botany. He did research in genetics at the Welsh Plant Breeding Station, Aberystwyth, during 1929-33. He then went to the Empire Cotton Growing Corporation's Cotton Research Station, Trinidad, B.W.I., remaining there until 1944. He was visiting professor of plant genetics at the Blandy Experimental Farm of the University of Virginia during 1944-45 ; after which he became scientific officer of the Agricultural Research Council, attached to the Plarit Breeding Institute, School of Agriculture, University of Cambridge. His work has included investigations on Asiatic cottons in collaboration with the Chinese Agricultural Research Bureau at Nanking.

CITRUS CYCLOPEDIA

CITRUS CYCLOPEDIA ORLAND E. WHITE ORLAND E. WHITE Blandy Experimental Farm, University of Virginia Search for other works by this author on: Oxford Academic PubMed Google Scholar Journal of Heredity, Volume 36, Issue 4, April 1945, Pages 110–112, https://doi.org/10.1093/oxfordjournals.jhered.a105471 Published: 01 April 1945

FURTHER DATA ON THE INHERITANCE OF LINT COLOR

Journal Article FURTHER DATA ON THE INHERITANCE OF LINT COLOR: In the Old World Cultivated Cottons Get access R. A. SILOW R. A. SILOW *The Blandy Experimental Farm, University of Virginia. Formerly Empire Cotton Growing Corporation, Cotton Research StationTrinidad, B.W.I. Search for other works by this author on: Oxford Academic PubMed Google Scholar Journal of Heredity, Volume 36, Issue 2, February 1945, Pages 62–64, https://doi.org/10.1093/oxfordjournals.jhered.a105456 Published: 01 February 1945

CHROMOSOME NUMBER AND PHYLOGENETIC RELATIONSHIPS IN THE EUPHORB ACEAE

CHROMOSOME NUMBER AND PHYLOGENETIC RELATIONSHIPS IN THE EUPHORB ACEAE

Plant Breeding — The Modern Way

Journal Article Plant Breeding — The Modern Way Get access ORLAND E. WHITE ORLAND E. WHITE The Blandy Experimental Farm, University of Virginia Search for other works by this author on: Oxford Academic PubMed Google Scholar Journal of Heredity, Volume 33, Issue 7, July 1942, Page 264, https://doi.org/10.1093/oxfordjournals.jhered.a105185 Published: 01 July 1942