BARDEN, L. S. (Department of Biology, University of North Carolina at Charlotte, Charlotte, NC 28223). The linear relation between stand yield and integrated light in a shade-adapted annual grass. Bull. Torrey Bot. Club 123: 122-125. 1996.-Many ecology textbooks state that the photosynthetic response of plants to varying light is represented by the response of single leaves, which is a downward concave curve that often reaches saturation. Single leaves of the shade-adapted, annual grass, Microstegium vimineum (Trinius) A. Camus, saturate at 25% full sunlight. However, two field experiments showed that stand dry weight yield at the end of the growing season was a linear function of integrated light, rather than a downward concave saturation-type curve. The linear relation for M. vimineum stands concurs with results of several agricultural studies and may have implications for forest growth models that assume saturation-type response curves for whole trees or forest canopies.
BARDEN, l.s.(北卡罗来纳大学夏洛特分校生物系，北卡罗来纳州夏洛特28223)。适荫一年生草林分产量与综合光照的线性关系。公牛。托里机器人。俱乐部123:122-125。1996.-许多生态学教科书指出，植物对变化光的光合响应以单叶的响应来表示，这是一条向下的凹曲线，经常达到饱和。单叶的遮荫，一年生草，Microstegium vimineum (Trinius) A. Camus，饱和在25%的充分阳光。然而，两个田间试验表明，生长季末林分干重产量与综合光照呈线性关系，而不是向下凹的饱和型曲线。葡萄分枝杆菌林分的线性关系与若干农业研究的结果一致，并可能对假设全树或森林冠层饱和型响应曲线的森林生长模型产生影响。
{"title":"The linear relation between stand yield and integrated light in a shade-adapted annual grass'","authors":"L. S. Barden","doi":"10.2307/2996069","DOIUrl":"https://doi.org/10.2307/2996069","url":null,"abstract":"BARDEN, L. S. (Department of Biology, University of North Carolina at Charlotte, Charlotte, NC 28223). The linear relation between stand yield and integrated light in a shade-adapted annual grass. Bull. Torrey Bot. Club 123: 122-125. 1996.-Many ecology textbooks state that the photosynthetic response of plants to varying light is represented by the response of single leaves, which is a downward concave curve that often reaches saturation. Single leaves of the shade-adapted, annual grass, Microstegium vimineum (Trinius) A. Camus, saturate at 25% full sunlight. However, two field experiments showed that stand dry weight yield at the end of the growing season was a linear function of integrated light, rather than a downward concave saturation-type curve. The linear relation for M. vimineum stands concurs with results of several agricultural studies and may have implications for forest growth models that assume saturation-type response curves for whole trees or forest canopies.","PeriodicalId":9453,"journal":{"name":"Bulletin of the Torrey Botanical Club","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1996-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2307/2996069","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68402837","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
SHEELEY, S. C. AND D. J. RAYNAL (College of Environmental Science and Forestry, State University of New York, Syracuse, NY 13210). The distribution and status of Vincetoxicum nigrum (L.) Moench, V. rossicum (Kleo.) Barb. and V. hirundinaria Medik. in eastern North America Bull. Torrey Bot. Club 123:148-156. 1996.Vincetoxicum nigrum (L.) Pers., (Kleo.) Barb., V. rossicum and V. hirundinaria Medik. (Asclepiadaceae) are exotic twining perennial herbs found in eastern North America. The nomenclatural status as well as the historical and current distribution of these plants were surveyed by studying floristic manuals of flora and journal literature and by examining herbarium specimens, and corresponding with authorities familiar with the species. Vincetoxicum rossicum is the most invasive of the species, often forming large colonies; it occurs from the northeastern Atlantic coast W to S Michigan and from S. Ontario to s. Pennsylvania. Vincetoxicum nigrum and V. hirduninaria appear less aggressive and have more limited patterns of distribution. Vincetoxicum nigrum occurs from the northeastern Atlantic Coast west to Missouri and Kansas and from southern Ontario to southern Pennsylvania. Vincetoxicum hirundinaria is found in southern Ontario, New York and Pennsylvania. Vincetoxicum species may persist for decades after establishment, spreading vegetatively and by means of polyembronic seeds.
(美国纽约州立大学环境科学与林业学院，纽约州锡拉丘兹13210)。长春花毒的分布与现状Moench, V. rosicum (Kleo.)倒钩。和水蛭。北美东部的牛。托里机器人。俱乐部123:148 - 156。1996.长春花(L.)珀耳斯。(Kleo。)倒钩。、蔷薇花和水仙花。是产于北美东部的外来的多年生缠绕草本植物。通过查阅植物区系手册、期刊文献、植物标本馆标本，并与熟悉该植物的权威机构联系，调查了该植物的命名现状、历史分布和现状。长春花是最具侵略性的物种，经常形成大的菌落;它发生在大西洋东北部海岸西至密歇根州南部和南安大略至宾夕法尼亚州南部。黑长春花毒菌和水蛭弧菌的侵袭性较弱，分布模式也比较有限。长在大西洋东北海岸向西至密苏里州和堪萨斯州，从安大略省南部到宾夕法尼亚州南部。在安大略南部，纽约和宾夕法尼亚州发现了长春花。长春花属植物在建立后可以持续几十年，通过营养传播和多胚种子传播。
{"title":"The distribution and status of species of Vincetoxicum in eastern North America","authors":"S. Sheeley, D. Raynal","doi":"10.2307/2996072","DOIUrl":"https://doi.org/10.2307/2996072","url":null,"abstract":"SHEELEY, S. C. AND D. J. RAYNAL (College of Environmental Science and Forestry, State University of New York, Syracuse, NY 13210). The distribution and status of Vincetoxicum nigrum (L.) Moench, V. rossicum (Kleo.) Barb. and V. hirundinaria Medik. in eastern North America Bull. Torrey Bot. Club 123:148-156. 1996.Vincetoxicum nigrum (L.) Pers., (Kleo.) Barb., V. rossicum and V. hirundinaria Medik. (Asclepiadaceae) are exotic twining perennial herbs found in eastern North America. The nomenclatural status as well as the historical and current distribution of these plants were surveyed by studying floristic manuals of flora and journal literature and by examining herbarium specimens, and corresponding with authorities familiar with the species. Vincetoxicum rossicum is the most invasive of the species, often forming large colonies; it occurs from the northeastern Atlantic coast W to S Michigan and from S. Ontario to s. Pennsylvania. Vincetoxicum nigrum and V. hirduninaria appear less aggressive and have more limited patterns of distribution. Vincetoxicum nigrum occurs from the northeastern Atlantic Coast west to Missouri and Kansas and from southern Ontario to southern Pennsylvania. Vincetoxicum hirundinaria is found in southern Ontario, New York and Pennsylvania. Vincetoxicum species may persist for decades after establishment, spreading vegetatively and by means of polyembronic seeds.","PeriodicalId":9453,"journal":{"name":"Bulletin of the Torrey Botanical Club","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1996-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2307/2996072","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68402949","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Australian Vegetation, Second Edition.","authors":"S. Handel, R. Groves, R. Hill","doi":"10.2307/2996076","DOIUrl":"https://doi.org/10.2307/2996076","url":null,"abstract":"","PeriodicalId":9453,"journal":{"name":"Bulletin of the Torrey Botanical Club","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1996-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2307/2996076","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68403016","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
HESSL, A. E., P. J. WEISBERG3 AND W L. BAKER (Department of Geography and Recreation, University of Wyoming, Laramie, WY 82071). Spatial variability of radial growth in the forest-tundra ecotone of Rocky Mountain National Park, Colorado. Bull. Torrey ecotone of Rocky Mountain National Park, Colorado. Bull. Torrey Bot. Club 123: 206-212. 1996.-Radial growth in trees has often been used to measure the relationship between climate and tree growth. Variation in radial growth with respect to environmental variables may indicate how trees in diverse landscapes may respond to climate change. The purpose of this study is to determine whether radial growth is spatially heterogeneous throughout the forest-tundra ecotone of Rocky Mountain National Park and whether this spatial variability can be related to environmental variables. Increment cores were taken from 5-10 of the largest trees in 59 sampling locations distributed across the forest-tundra ecotone of Rocky Mountain National Park. Mean annual ring width for 1978-1987 was measured in the laboratory. Stepwise weighted least squares linear regression was used to relate mean annual growth to 25 environmental variables measured at each sampling location. Mean radial growth is higher at sampling locations with higher soil pH values and where there is small rock material but varies with zone and associated shrub species. When all statistically significant variables are considered, radial growth is slowest in the krummholz zone, intermediate in the patch forest zone, and fastest in the closed forest zone. Within each zone, the presence of Juniperus communis indicates slow radial growth, Vaccinium spp. indicate intermediate radial growth, and Salix spp. indicate rapid radial growth. These results differ from previous studies of vertical seedling leader growth in the FTE, which found higher rates of growth in the krummholz zone. Differing rates of radial and vertical growth may reflect different settings or different responses, though both may indicate tree "success."
HESSL, A. E. P. J. WEISBERG3和W . L. BAKER(怀俄明大学地理与娱乐系，怀俄明州拉勒米，WY 82071)。科罗拉多州落基山国家公园森林-冻土带过渡带径向生长的空间变异。公牛。科罗拉多州落基山国家公园的托里过渡带。公牛。托里机器人。俱乐部123:206-212。1996.树木的径向生长常被用来衡量气候和树木生长之间的关系。径向生长随环境变量的变化可能表明不同景观中的树木如何对气候变化作出反应。本研究的目的是确定整个落基山国家公园森林-苔原过渡带的径向生长是否具有空间异质性，以及这种空间变异性是否与环境变量有关。在落基山国家公园森林-冻土带交错带的59个采样点中，从5-10棵最大的树木中提取增量岩心。在实验室测量了1978-1987年的平均年轮宽度。采用逐步加权最小二乘线性回归将平均年增长率与每个采样地点测量的25个环境变量联系起来。平均径向生长在土壤pH值较高的取样地点和有小岩石材料的取样地点较高，但因带和伴生灌木种类而异。当考虑所有统计上显著的变量时，径向生长在克鲁姆霍兹区最慢，在斑块林区居中，在封闭林区最快。在各带内，朱柏(Juniperus communis)呈缓慢径向生长，杨柳(Vaccinium)呈中等径向生长，柳(Salix)呈快速径向生长。这些结果不同于以前在FTE中对垂直苗头生长的研究，后者发现krummholz区生长速率更高。不同的径向和垂直生长速率可能反映不同的环境或不同的响应，尽管两者都可能表明树木的“成功”。
{"title":"Spatial variability of radial growth in the forest-tundra ecotone of Rocky Mountain National Park, Colorado","authors":"A. Hessl, P. Weisberg, W. Baker","doi":"10.2307/2996796","DOIUrl":"https://doi.org/10.2307/2996796","url":null,"abstract":"HESSL, A. E., P. J. WEISBERG3 AND W L. BAKER (Department of Geography and Recreation, University of Wyoming, Laramie, WY 82071). Spatial variability of radial growth in the forest-tundra ecotone of Rocky Mountain National Park, Colorado. Bull. Torrey ecotone of Rocky Mountain National Park, Colorado. Bull. Torrey Bot. Club 123: 206-212. 1996.-Radial growth in trees has often been used to measure the relationship between climate and tree growth. Variation in radial growth with respect to environmental variables may indicate how trees in diverse landscapes may respond to climate change. The purpose of this study is to determine whether radial growth is spatially heterogeneous throughout the forest-tundra ecotone of Rocky Mountain National Park and whether this spatial variability can be related to environmental variables. Increment cores were taken from 5-10 of the largest trees in 59 sampling locations distributed across the forest-tundra ecotone of Rocky Mountain National Park. Mean annual ring width for 1978-1987 was measured in the laboratory. Stepwise weighted least squares linear regression was used to relate mean annual growth to 25 environmental variables measured at each sampling location. Mean radial growth is higher at sampling locations with higher soil pH values and where there is small rock material but varies with zone and associated shrub species. When all statistically significant variables are considered, radial growth is slowest in the krummholz zone, intermediate in the patch forest zone, and fastest in the closed forest zone. Within each zone, the presence of Juniperus communis indicates slow radial growth, Vaccinium spp. indicate intermediate radial growth, and Salix spp. indicate rapid radial growth. These results differ from previous studies of vertical seedling leader growth in the FTE, which found higher rates of growth in the krummholz zone. Differing rates of radial and vertical growth may reflect different settings or different responses, though both may indicate tree \"success.\"","PeriodicalId":9453,"journal":{"name":"Bulletin of the Torrey Botanical Club","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1996-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2307/2996796","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68411268","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Vascular Plants of Russia and Adjacent States (The Former USSR).","authors":"L. Struwe, S. Czerepanov","doi":"10.2307/2996309","DOIUrl":"https://doi.org/10.2307/2996309","url":null,"abstract":"","PeriodicalId":9453,"journal":{"name":"Bulletin of the Torrey Botanical Club","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1996-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2307/2996309","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68405129","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
L. Bruederle, Michael S. Hugan, Jennifer M. Dignan, N. Vorsa, N. Vorsa
1816, the large cranberry has become a regionally important small fruit crop in the United States. In order to assess genetic variation in naturally occurring populations of the large cranberry, sampling was conducted at ten sites distributed from Wisconsin east to Massachusetts, and south to Delaware. Starch gel electrophoresis and substrate-specific staining techniques were used to resolve 23 putative Mendelian loci. Population data collected as individual genotypes were analyzed, generating measures of population structure and genetic diversity. All populations were found to exhibit low levels of genetic variation, e.g., expected heterozygosity (Hexp 0.00 + 0.002-0.057 + 0.030). Relative to other plant species, total genetic diversity was extremely low (H, 0.048) with the majority of all genetic variation due to differences among individuals within populations. This genetic homogeneity was corroborated by Nei's (1978) genetic identity which ranged from 0.977 to one. Recent events in the evolutionary history of this taxon are proposed to have played an important role in determining population genetic structure in this species.
{"title":"Genetic variation in natural populations of the large cranberry, Vaccinium macrocarpon Ait. (Ericaceae)'","authors":"L. Bruederle, Michael S. Hugan, Jennifer M. Dignan, N. Vorsa, N. Vorsa","doi":"10.2307/2996305","DOIUrl":"https://doi.org/10.2307/2996305","url":null,"abstract":"1816, the large cranberry has become a regionally important small fruit crop in the United States. In order to assess genetic variation in naturally occurring populations of the large cranberry, sampling was conducted at ten sites distributed from Wisconsin east to Massachusetts, and south to Delaware. Starch gel electrophoresis and substrate-specific staining techniques were used to resolve 23 putative Mendelian loci. Population data collected as individual genotypes were analyzed, generating measures of population structure and genetic diversity. All populations were found to exhibit low levels of genetic variation, e.g., expected heterozygosity (Hexp 0.00 + 0.002-0.057 + 0.030). Relative to other plant species, total genetic diversity was extremely low (H, 0.048) with the majority of all genetic variation due to differences among individuals within populations. This genetic homogeneity was corroborated by Nei's (1978) genetic identity which ranged from 0.977 to one. Recent events in the evolutionary history of this taxon are proposed to have played an important role in determining population genetic structure in this species.","PeriodicalId":9453,"journal":{"name":"Bulletin of the Torrey Botanical Club","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1996-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2307/2996305","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68405562","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
LECK, M. A. (Biology Department, Rider University, Lawrenceville, NJ 08648). Germination of macrophytes from a Delaware River tidal freshwater wetland. Bull. Torrey Bot. Club 123: 48-67. 1996. The effects of burial and soil moisture (seeds were on the surface, or buried at 1 and 5 cm with drained, saturated, or flooded water levels), inundation (Petri dishes, and open and closed jars), and storage (-0 and -100% RH), as well as of light and various temperature regimes, were examined. Focus was on ten species (Amaranthus cannabinus (L.) Sauer, Ambrosia trifida L., Bidens laevis (L.) BSP, Impatiens capensis Meerb., Peltandra virginica (L.) Schott. & Endl., Phalaris arundinacea L., Pilea pumila (L.) A. Gray, Polvgonum arifblium L., Polygonum punctatum Elliott, and Sagittaria latifolia Willd.); five others were also considered to a limited extent (Alisma subcordatum Raf., Carex lurida Wahlenb., Cicuta maculata L., Cuscuta gronovii Willd., and Pontederia cordata L.). Species varied in their germination responses. Those with the same seed bank strategy (transient or persistent) had different dormancy mechanisms although seeds with persistent seed banks required temperatures >50C and germination for most was enhanced by light. Responises to burial and moisture level showed that larger seeded species were able to germinate from greater depth, but germination was greater in drained samples. There were three types of responses to inundation: (1) requirement for at least modest amounts of oxygen, (2) requirement for hypoxic conditions, and (3) those having good germination regardless of inundation regime. Seed bank losses and relatively short seed bank longevity could be accounted for by germination following afterripening, adverse effects of prolonged inundation, failed gerrnination (e.g., germination at depths that preclude the seedling from reaching the surface), and predation. Differences between the seed characteristics of species of this and those of other wetlands relate to the transient nature of the seed bank and to wetland hydrology. Variable responses to drying have implications for wetland restoration projects.
{"title":"Germination of macrophytes from a Delaware River tidal freshwater wetland","authors":"M. A. Leck","doi":"10.2307/2996306","DOIUrl":"https://doi.org/10.2307/2996306","url":null,"abstract":"LECK, M. A. (Biology Department, Rider University, Lawrenceville, NJ 08648). Germination of macrophytes from a Delaware River tidal freshwater wetland. Bull. Torrey Bot. Club 123: 48-67. 1996. The effects of burial and soil moisture (seeds were on the surface, or buried at 1 and 5 cm with drained, saturated, or flooded water levels), inundation (Petri dishes, and open and closed jars), and storage (-0 and -100% RH), as well as of light and various temperature regimes, were examined. Focus was on ten species (Amaranthus cannabinus (L.) Sauer, Ambrosia trifida L., Bidens laevis (L.) BSP, Impatiens capensis Meerb., Peltandra virginica (L.) Schott. & Endl., Phalaris arundinacea L., Pilea pumila (L.) A. Gray, Polvgonum arifblium L., Polygonum punctatum Elliott, and Sagittaria latifolia Willd.); five others were also considered to a limited extent (Alisma subcordatum Raf., Carex lurida Wahlenb., Cicuta maculata L., Cuscuta gronovii Willd., and Pontederia cordata L.). Species varied in their germination responses. Those with the same seed bank strategy (transient or persistent) had different dormancy mechanisms although seeds with persistent seed banks required temperatures >50C and germination for most was enhanced by light. Responises to burial and moisture level showed that larger seeded species were able to germinate from greater depth, but germination was greater in drained samples. There were three types of responses to inundation: (1) requirement for at least modest amounts of oxygen, (2) requirement for hypoxic conditions, and (3) those having good germination regardless of inundation regime. Seed bank losses and relatively short seed bank longevity could be accounted for by germination following afterripening, adverse effects of prolonged inundation, failed gerrnination (e.g., germination at depths that preclude the seedling from reaching the surface), and predation. Differences between the seed characteristics of species of this and those of other wetlands relate to the transient nature of the seed bank and to wetland hydrology. Variable responses to drying have implications for wetland restoration projects.","PeriodicalId":9453,"journal":{"name":"Bulletin of the Torrey Botanical Club","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1996-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2307/2996306","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68405576","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
CHEPLICK, G. P (Department of Biology, The College of Staten Island of the City University of New York, Staten Island, NY 10314). Cleistogamy and seed heteromorphism in Triplasis purpurea (Poaceae). Bull. Torrey Bot. Club 123: 25-33. 1996.-Two populations of the annual grass Triplasis purpurea on Staten Island, New York, were examined to determine the importance of cleistogamy (CL) to caryopsis (seed) production, and whether CL was associated with a position-dependent seed heteromorphism, as noted in other CL grasses. The percentage of tillers with terminal panicles bearing chasmogamous spikelets was low in both populations (s35%), and at least 72% of the seeds produced by tillers with terminal panicles were matured on axillary panicles in CL spikelets enclosed by leaf sheaths. A marked seed heteromorphism exists in T. purpurea: from the lower to the upper nodes along a tiller, there was an increase in seed number with a concurrent decrease in mean seed mass. This heteromorphism was further investigated in a greenhouse experiment where plants were subjected to low, medium, and high levels of soil nutrients by periodic addition of N-P-K fertilizer. Again, there was a progressive increase in seed number with a concordant decrease in mean seed mass from the lower to the upper tiller nodes. Differences in seed number among nutrient treatment groups were greatest in the upper nodes, but differed very little in the lower nodes. This is the first report of seed heteromorphism in this species. It is suggested that the position-dependent variation in seed mass reflects differences in the timing and length of the maturation period. From an evolutionary perspective, this pattern of seed heteromorphism may represent an adaptation to an unpredictable, highly-disturbed environment.
{"title":"Cleistogamy and seed heteromorphism in Triplasis purpurea (Poaceae)","authors":"G. P. Cheplick","doi":"10.2307/2996303","DOIUrl":"https://doi.org/10.2307/2996303","url":null,"abstract":"CHEPLICK, G. P (Department of Biology, The College of Staten Island of the City University of New York, Staten Island, NY 10314). Cleistogamy and seed heteromorphism in Triplasis purpurea (Poaceae). Bull. Torrey Bot. Club 123: 25-33. 1996.-Two populations of the annual grass Triplasis purpurea on Staten Island, New York, were examined to determine the importance of cleistogamy (CL) to caryopsis (seed) production, and whether CL was associated with a position-dependent seed heteromorphism, as noted in other CL grasses. The percentage of tillers with terminal panicles bearing chasmogamous spikelets was low in both populations (s35%), and at least 72% of the seeds produced by tillers with terminal panicles were matured on axillary panicles in CL spikelets enclosed by leaf sheaths. A marked seed heteromorphism exists in T. purpurea: from the lower to the upper nodes along a tiller, there was an increase in seed number with a concurrent decrease in mean seed mass. This heteromorphism was further investigated in a greenhouse experiment where plants were subjected to low, medium, and high levels of soil nutrients by periodic addition of N-P-K fertilizer. Again, there was a progressive increase in seed number with a concordant decrease in mean seed mass from the lower to the upper tiller nodes. Differences in seed number among nutrient treatment groups were greatest in the upper nodes, but differed very little in the lower nodes. This is the first report of seed heteromorphism in this species. It is suggested that the position-dependent variation in seed mass reflects differences in the timing and length of the maturation period. From an evolutionary perspective, this pattern of seed heteromorphism may represent an adaptation to an unpredictable, highly-disturbed environment.","PeriodicalId":9453,"journal":{"name":"Bulletin of the Torrey Botanical Club","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1996-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2307/2996303","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68405470","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Relative abundance of the two species varies with availability of the appropriate regeneration niche, which is a function of the local disturbance regime. Rodent activity may both produce the gaps favored by D. flagellare and facilitate its dispersal to them. Dominance of T. pellucida is associated with larger gaps produced by decay. The interaction of the regeneration niche and the disturbance regime are found to be primary determinants of community structure on this unstable substrate.
{"title":"Effect of gap size and regeneration niche on species coexistence in bryophyte communities","authors":"R. W. Kimmerer, C. Young","doi":"10.2307/2996302","DOIUrl":"https://doi.org/10.2307/2996302","url":null,"abstract":"Relative abundance of the two species varies with availability of the appropriate regeneration niche, which is a function of the local disturbance regime. Rodent activity may both produce the gaps favored by D. flagellare and facilitate its dispersal to them. Dominance of T. pellucida is associated with larger gaps produced by decay. The interaction of the regeneration niche and the disturbance regime are found to be primary determinants of community structure on this unstable substrate.","PeriodicalId":9453,"journal":{"name":"Bulletin of the Torrey Botanical Club","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1996-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2307/2996302","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68405459","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"More on the Southward Spread of Common Milkweed, Asclepias syriaca L.","authors":"R. Wyatt","doi":"10.2307/2996307","DOIUrl":"https://doi.org/10.2307/2996307","url":null,"abstract":"","PeriodicalId":9453,"journal":{"name":"Bulletin of the Torrey Botanical Club","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1996-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2307/2996307","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68405119","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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