摘要:

Pure stands ofPinus remorataregularly occur in more equable sites than those occupied byP. muricata.The fossil record suggests that this relationship has existed since at least the earliest Pleistocene. It apparently was the spread of drier, less equable, postglacial climate that opened new, intermediate coastal sites that favored hybrids ofP. muricata × P. remorata, the latter a relict species closely allied toP. radialavar.cedrosensis.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1990.tb13557.x

出版商:Wiley    

年代:1990

数据来源: WILEY

摘要:

Two genetic variants with increased organ size were independently derived from diploid (2n= 2x= 16) chickpea (Cicer arietinumL.) line ICC 640. Radiation‐induced mutant PM1101 had greatly enlarged leaves, leaflets, and pods, and an elongated stem with longer internodes but fewer nodes than ICC 640. F1, F2, and F3data from crosses with ICC 640 showed that the mutant characteristics of PM1101 were the pleiotropic effects of a single, recessive genetic factor. For purposes of comparison, tetraploid derivatives of ICC 640 were produced by colchicine treatment of seed. In the tetraploids, leaflets and pods were enlarged, but less dramatically than in PM1101. Enlarged pollen grains and stomatal guard cells, and increased guard cell chloroplast number were found in tetraploids but not in PM1101, while both variants produced fewer seeds than ICC 640. Mutant PM1101 and the tetraploids represent two very different manifestations of gigantism in chickpea.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1990.tb13558.x

出版商:Wiley    

年代:1990

数据来源: WILEY

摘要:

Two genomic variants of a chickpea (Cicer arietinumL.) parental line have been developed which exhibit gigas characters. The two genotypes were the result of a single‐gene mutation (gigas) and induced tetraploidy of a single parental line. The two genotypes plus parental strain were investigated to determine the similarity‐of‐effect of polyploidy and this single‐gene mutation on leaf anatomy and morphology. Leaves consisted of two rows of alternatively arranged leaflets. Both the tetraploid and parental lines had the same mean number of leaflets per leaf while the gigas plants had fewer, but mean total leaf surface area was greater in the gigas plants. Quantitative comparison of mesophyll and vascular tissue and air space volume density (Vv) showed that leaves of the tetraploid plants had the greatest mesophyll cell density (Vvm) and least air space density. Mesophyll cell density was equal in the parental and single‐gene mutant while parental leaves had the greatest vascular tissue density. The greater mesophyll cell density values of the polyploid were due to larger mean mesophyll cell size, not to greater cell numbers per unit area. Leaf models based on tissue density and leaflet size showed tetraploid plants had the greatest productivity potential per unit of leaflet surface area. However, if models were based on a whole leaf, gigas plants had the greatest productivity potential since they had larger total leaf area. The effectiveness of using structural models to predict physiological potential in plant tissues will be tested in future studies.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1990.tb13559.x

出版商:Wiley    

年代:1990

数据来源: WILEY

摘要:

Vegetative, fruit, and floral characters of more than 200 herbarium specimens ofAcacia constrictaand closely related species from the Southwestern U.S. and Mexico were scored and analyzed by principal components analysis (PCA) and stepwise discriminant analysis (SDA). The results show that all of the 5 species of this group are distinct and form nonoverlapping groups in plots of the first three principal components. All taxa were found to be quite homogeneous as indicated by the tight clusters formed in the PCA plots.Acacia pacensis, whose relationship to the species of this group has been questioned, is confirmed to be more closely related toA. farnesianaand related species. Some specimens with a combination of characters fromA. constricta, A. neovernicosa, andA. schottiiwere positioned intermediate to the putative parental species groups in the PCA and SDA plots, suggesting hybridization among these taxa.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1990.tb13560.x

出版商:Wiley    

年代:1990

数据来源: WILEY

摘要:

Various organs ofLeucaena leucocephala(Lam.) de Wit were analyzed for their levels of total nitrogen and free amino acids as well as for changes in free amino acid pools from the time of germination through nodulation. Also an assessment was made of the sink of fixed N2(transport product) in the nodules using15N methodology.L. leucocephalaorgans showed total nitrogen levels similar to those of other legumes. Asparagine was the most prevalent amino acid in the nodules and roots followed by glutamate and mimosine. Asparagine was the second most common amino acid in the leaves and stems, with mimosine being the most abundant. Strong correlations were found between the total plant levels of aspartate and glutamate, asparagine and NH4+, acetylene reduction and glutamate, and asparagine and plant age. Asparagine amino‐ and amide‐N accounted for over 75% of the fixed15N2in nodules. It was concluded thatL. leucocephalais an asparagine transporter of fixed N2in the nodule.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1990.tb13561.x

出版商:Wiley    

年代:1990

数据来源: WILEY

摘要:

There is a wide range of variation among individuals in the degree of incision of leaf margins in the AfricanBegonia dregei.The development of adult leaves was examined in six varieties ofB. dregei.There are several types of differences in development that correlate with the shapes of mature leaves. The shoot apex is larger and the leaf primordia are broader soon after initiation in a variety with entire margins than in those with more incised leaves. One variety differs from the others in the temporal pattern of initiation of the lobes, corresponding to differences in the relative sizes of the lobes of the mature leaves. The differences among varieties in the extent of incision of the margin are apparent during the first plastochron, before the primordia are 300μm in length. All are more deeply incised early than when mature. Growth rates of the different parts of the leaves change with respect to each other during development in the more deeply incised varieties. The leaves of the three least incised varieties reach similar mature shapes by two different developmental pathways. Differences in the relative timing of developmental processes provide a description of some of the evolutionary changes responsible for differences in shape. However, simple heterochrony does not describe all aspects of the diversification of leaf shape in this species.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1990.tb13562.x

出版商:Wiley    

年代:1990

数据来源: WILEY

摘要:

The Casuarinaceae consists of the 4 generaGymnostoma, Ceuthostoma, CasuarinaandAllocasuarina.All the genera are found living today in Australia, Malaysia, Melanesia, and Southeast Asia. An abundant and widespread fossil record of the genusGymnostomais known from New Zealand, Argentina, South Africa, and Australia. This paper provides a compilation of basic vegetative and reproductive morphological data of the 4 genera of the Casuarinaceae with special emphasis on these features inGymnostoma.The features are presented in tabular form and the data are compared and discussed. Most of the genera can be clearly distinguished by the morphology of their vegetative and reproductive organs. Species differences within the extant genera often are difficult to distinguish; therefore, comparative systematic analysis of these fossils from fragmentary and incomplete remains ranging through time will be very difficult, and care must be taken when interpreting evolutionary trends from them.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1990.tb13563.x

出版商:Wiley    

年代:1990

数据来源: WILEY

摘要:

The numbers of microgametophytes in the stigmas of the outcrossingPhlox drummondiiwere determined in 19 natural populations. Microgametophyte numbers per stigma ranged from 0 to over 40 in each population. The number of flowers per plant, distance to the nearest‐neighbor, and number of plants within 1 m of the focal plants explained about 23% of the variation in microgametophyte numbers within 2 of the populations. The mean number per stigma across all populations was 14.34; and the mean number per population varied from 7.77 to 19.52. Given that there are 3 ovules per flower, there was an average of 4.73 microgametophytes per ovule. Sixty‐nine percent of all pistils contained more than 3 microgametophytes, thereby presenting an opportunity for intergametophytic competition.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1990.tb13564.x

出版商:Wiley    

年代:1990

数据来源: WILEY

摘要:

Atriplex pleianthaWeber differs from all other species ofAtriplexin having 1) multiple female flowers subtended by two bracts, 2) female flowers with a perianth, and 3) embryos with radicles pointing downwards. Because of these significant differences it is proposed thatAtriplex pleianthabe elevated to the level of a separate genus and be designatedProatriplex pleiantha(Weber) Stutz&Chu. The closest relatives ofProatriplexappear to beArchiatriplex, Endolepis, Exomis, andMicrogynoecium.These are all diploid, monoecious annuals, have non‐Kranz type leaf anatomy, and female flowers with a perianth.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1990.tb13565.x

出版商:Wiley    

年代:1990

数据来源: WILEY

摘要:

Thirteen shade‐adapted rain forest species were compared with twelve sun‐adapted tropical forest species for correlates to leaf optical properties (described previously in Amer. J. Bot. 73: 1100–1108). The two samples were similar in absorptance of quanta for photosynthesis, but the shade‐adapted taxa: 1) had significantly lower specific leaf weights, indicating a more metabolically efficient production of surface for quantum capture; 2) synthesized less chlorophyll per unit area; and 3) used less chlorophyll for capturing the same quanta for photosynthesis. The anatomical features that best correlate with this increased efficiency are palisade cell shape and chloroplast distribution. Palisade cells with more equal dimensions have more chloroplasts on their abaxial surfaces. This dense layer of chloroplasts maximizes the light capture efficiency limited by sieve effects. The more columnar palisade cells of sun‐adapted taxa allow light to pass through the central vacuoles and spaces between cells, making chloroplasts less efficient in energy capture, but allowing light to reach chloroplasts in the spongy mesophyll. Pioneer species may be an exception to these two groups of species. Three pioneer taxa included in this study have columnar palisade cells that are extremely narrow and packed closely together. This layer allows little penetration of light, but exposure of the leaf undersurface may provide illumination of spongy mesophyll chloroplasts in these plants.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1990.tb13566.x

出版商:Wiley    

年代:1990

数据来源: WILEY