摘要:

AbstractEriastrum densifoliumssp.sanctorum(Milliken) Mason is a geographically restricted subspecies occurring only in a short stretch of the Santa Ana River Wash, in southern California. This subspecies is considered endangered and has been afforded US federal protection. Enzyme electrophoresis was used to assess its genetic variability and its relationship to other nearby conspecific populations, which are morphologically similar to ssp.sanctorum. Gene diversity is higher than expected for this endemic taxon. Most of the genetic variation in this subspecies resides within the sites comprising the single, large population. Analysis of nearby populations involving other subspecies ofEriastrum densifoliumindicate that these entities are very closely related to the Santa Ana River population. The genetic vulnerability of this plant appears to be low, and the relationship to other nearby, morphologically similar populations is uncertain.

ISSN:0913-557X    

DOI:10.1111/j.1442-1984.1993.tb00228.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractVariability in life history traits and phenology of field populations ofCardamine flexuosaandC. fallaxwas investigated.C. flexuosais an annual that typically grows all year around and occurs as a weed in cultivated fields such as paddy fields, crop gardens and orchards.C. fallaxis a typical winter‐green annual that mainly grows along the roadside on foothills. Differences in growth form of both species corresponded to variations in habitat conditions. Plants of paddy field populations ofC. flexuosanormally possess many basal branches, while those of orchard populations ofC. flexuosatypically have an erect growth form with few basal branches.C. fallaxalso possesses a typical erect growth form. Other life history traits (e.g., individual plant biomass and reproductive traits) of both species were highly variable both within and between populations. InC. flexuosa, seasonal differences were also found in flowering and fruiting performance. Synchronous flowering of all plants was observed in spring populations, while partial flowering occurred in summer‐autumn populations. Differences in the size class structure of plants in the autumn appeared to be caused by different cultivation schedules for crop plants in the fields.C. fallax, in contrast, possesses a rather fixed seasonal growth cycle as a typical winter‐green annual with a synchronized flowering in s

ISSN:0913-557X    

DOI:10.1111/j.1442-1984.1993.tb00229.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractSeedling growth and morphology of the deciduous treeCornus controversafrom subtropical China were studied in four simulated forest gap light environments: 100%, 55%, 33% and 18% full sunlight. The best performance was in 33% full sunlight. Overall,Cornusseedlings grew taller than those of five broad‐leaved evergreen species from the same area. In terms of total plant mass onlyCinnamomum camphoraseedlings grew bigger thanCornusseedlings. Cornus seedlings needed relatively small biomass investments to become tall and to produce a great total length of axes. Growth ofCornusseedlings was probably enhanced by their comparatively ‘cheap’ leaves in terms of weight per area, which resulted in large total leaf area per unit plant weight. The results provide ecophysiological support ofCornus' competitive strength in forest gaps amidst mostly everg

ISSN:0913-557X    

DOI:10.1111/j.1442-1984.1993.tb00230.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractSize‐specific effects on the resource allocation pattern and gender variation at the flowering stage were studied in a perennial hermaphrodite,Anemone debilis. With an increase of plant size, allocations to inflorescence and roots decreased, while those to leaves and stem were constant; allocations to rhizome increased. A negative correlation between sexual reproduction and survival or vegetative reproduction was suggested. There was a trade‐off in resource allocation between male function (androecium) and female function (gynoecium) within an inflorescence. Gender ofA. debilisgradually shifted to femaleness with size increment. This size‐specific sex allocation pattern agrees with the prediction of the theoretical model for entomophilous hermaphroditic p

ISSN:0913-557X    

DOI:10.1111/j.1442-1984.1993.tb00231.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractField collections and measurements of corolla tubes andBombustongues indicated thatPedicularis palustris, an early summer‐blooming plant on Ile aux Grues and Ile aux Oies in the St. Lawrence River, Canada, is pollinated nototribically by queens of four species of bumblebees foraging for nectar and sternotribically by three species ofBombusworkers scraping pollen from anthers concealed in the galea. Short‐tongued workers ofB. terricolasecured nectar by perforating the base of the corolla tube dorsally or ventrally and, in some cases, pollinated the flower while robbing nectar. The flowers are insect‐dependent for pollination and are almost exclusively bumblebee‐pollinated. Sugar concentration of nectar, determined by refractometry, ranged from 8.0% to 19.5% (mean = 13.9%), and fructose and sucrose components of nectar samples from North America and the Netherlands were detected by thin‐layer chromatography. Excavated roots ofPedicularis palustrisconfirmed its root‐hemiparasitism. Parallel pollination studies were carried out onHypericum perforatumandVicia craccaon the mainland in the same area which bloomed later thanPedicularisand were pollinated primarily byBombusworkers. Predominance of queen pollinators onPedicularisand worker foragers onHypericumandViciaand analysis of corbicular pollen loads of foragers suggest a phenological relationship betweenPedicularis palustrisand the annual reproductive cycle of its bumblebee pollinators previously derived from investigations of other North American and Japan

ISSN:0913-557X    

DOI:10.1111/j.1442-1984.1993.tb00232.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractInter‐ and intrapopulation pollen‐mediated gene flow was estimated in a population ofCynanchum grandifoliumvar.nikoenseby paternity analysis of all the seeds set in 1990. By the simple exclusion procedure, the rate of genes migrating by pollen into this population was estimated to be 0.083; this value is lower than that estimated in most previous studies. Frequency distributions of intrapopulation pollen‐mediated gene flow distances estimated by different methods of paternity analysis were platykurtic, and the estimated distances of realized gene flow were smaller than the interplant dis

ISSN:0913-557X    

DOI:10.1111/j.1442-1984.1993.tb00233.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractDisruptive selection was observed in the flowering time ofWyethia amplexicaulisbetween two sites at different altitudes. Flowering time varied with elevation. Flowering occurred in late June in the lower sites and in mid July in the higher sites. In the lower sites, earlier blooming flowerheads produced more good seeds, but in the higher sites later blooming flowerheads were more successful. Successful seed production observed in this study was very low (4.0% on average) since some ovules or developing seeds are attacked by insect seed predators and others are aborted. In the early flowering plants, seed production was reduced primarily by the high predation rate, while in the late flowering plants the high abortion rate was important. In early July, the interval between the two flowering peaks, both factors had a significant effect on seed production. Causes of seed abortion are also discussed.

ISSN:0913-557X    

DOI:10.1111/j.1442-1984.1993.tb00234.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractAt 0‐ to 12‐week intervals, imbibed achenes of ten perennial Asteraceae from eastern North America were removed from 5°C (cold stratification) and tested for germination over a range of daily thermoperiods. The objective was to determine changes in the temperature requirements for germination as achenes came out of dormancy (after‐ripened). InEupatorium fistulosum, Helenium autumnale, Kuhnia eupatorioides, Mikania scandens, Ratibida pinnata, Solidago altissimaandVerbesina alternifolia, the minimum temperature for germination decreased during afterripening (Type 2 response), and inAster divaricatus, Echinacea simulataandE. tennesseensisthe minimum and maximum temperatures decreased and increased, respectively (Type 3 response). The majority of the 32 species of Asteraceae whose afterripening pattern has been investigated have a Type 2 response, and the family is one of many in eastern North America with species that have Type 2. We hypothesize that the ancestors giving rise to species with Type 2 were species with (1) nondormant seeds that required high temperatures for germination, or (2) dormant seeds that afterripened during warm (dry) winters and germinated only at high temper

ISSN:0913-557X    

DOI:10.1111/j.1442-1984.1993.tb00235.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

ISSN:0913-557X    

DOI:10.1111/j.1442-1984.1993.tb00236.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY