摘要:

A population of the annualLasthenia californicain the Jasper Ridge Biological Preserve (of Stanford University) showed three major flavonoid pigment types (A, B and C; a fourth was seen in very low frequencies). The three more common types exhibited a suite of aurone and chalcone glucosides and a set of highly polar flavonoid glucuronides. Type C consisted solely of the base array; type B added luteolin 7‐glucoside to the base array, while type A exhibited the base array plus eriodictyol 7‐glucoside and flavonol 3,7‐diglycoside bisulfates. The rare type D profile resembled type A except that the diglycosides were not sulfated. Collections were made along one of several fixed transects annually from 1982 to 1987. The main transect studied (Transect No. I) can be divided into two distinct parts on the basis of a changeover of flavonoid pattern from a mixture of types B and C at one end to exclusively (or very nearly) type A at the other. The frequencies of types B and C varied from year to year with type C predominating every year. The frequency of type A plants remained remarkably stable over the six‐year period. Collections along other transects showed a similar constancy of both frequencies of the flavonoid types and location of the types along the transects. Growth experiments in a greenhouse showed that seeds from type A parents harvested in the field produced only type A progeny, while type B and C plants gave only type B and C progeny with type C predominating (a single type A progeny plant was obtained from a type C parent). Flavonoid diversity inL. californicaappears to be genetically controlled and is influenced significantly by the flavonoid chemistry of the seed parent.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1989.tb11298.x

出版商:Wiley    

年代:1989

数据来源: WILEY

摘要:

In most plant species with abiotic pollination systems, pollen is dispersed in three dimensions. Theoretical considerations suggest, however, that there are significant advantages for two‐dimensional pollination systems over three‐dimensional systems, especially if pollen is dispersed in conveyances or aggregations of large diameter. We report that two‐dimensional pollination systems occur in the generaHalodule, Halophila, Lepilaena, andRuppia, where pollen grains are not transported through the water singly, but in rafts or search vehicles. These genera possess unusual pollen morphologies which facilitate assemblage of pollen grains into search vehicles. These floating search vehicles have large diameters, thus greatly increasing probability of encountering a stigma. The grains have a hydrophobic surface that appears to mediate adhesion by an external coating of proteins and carbohydrates. Similar adaptations to two‐dimensional pollination are found in the target organs, the stigmas. The long filamentous stigmas of the marine genera float, as do the indusiate stigmas of the freshwater genera, creating small depressions in the water surface. Pollination occurs through the collision of a moving search vehicle with a floating stigma. The existence of similar pollen search vehicles, stigma morphologies, and flowering phenologies in these unrelated hydrophilous genera evidences convergent evolution towards efficient search strategies in surface‐pollinated aquatic plants.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1989.tb11299.x

出版商:Wiley    

年代:1989

数据来源: WILEY

摘要:

A single structurally preserved ovulate cone forms the basis for the description of a new species ofPityostrobusfrom the early Oligocene of the Olympic Peninsula of Washington. The specimen consists of about two‐thirds of a cylindrical cone. In living condition the cone was 8–10 cm long and 3.5–4 cm in diameter. Critical features of the cone include decurrent bract bases, an elongate bract‐scale adnation, perpendicular disposition of the proximal part of the scale, and seeds with vesciculate seed coat. An unusual feature of the cone is a distinctive cortical region of thin‐walled parenchyma, mineral‐filled lacunae, and resin canals. This region can be traced to the adaxial side of the scale where it can be recognized by an extensive development of resin canals in the adaxial ground tissue opposite the seed cavities, and by distinctive lacunae around the vascular bundles. The fossil shares several significant characters with modern cones ofAbies, Pseudotsuga, Larix, Tsuga, andPicea, thereby calling to question the abietoid/pinoid division of the family, or suggesting that abietoid and pinoid genera of the early Oligocene had not yet diverged to the extent seen in the modern flora.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1989.tb11300.x

出版商:Wiley    

年代:1989

数据来源: WILEY

摘要:

It is an axiom in biology that genes control the ontogeny and ultimately the final form of an organism. In plants a given morphological form can often arise through more than one ontogenetic pattern of cell divisions. Different ontogenetic patterns have different properties with regard to the final age in cell divisions of the initials in the meristems for a given morphological form. If mutation per genome per cell division is an important biological metric, then since the age of a cell in cell divisions is a function of ontogeny, the cellular ontogeny will influence the degree of mutation‐loading in meristematic initials. Thus, ontogeny and form may affect the genes (by promoting or lessening genomic stasis) as well as, of course, being determined by the genes. This paper explores mathematically the relationship between different patterns of cell division and mutation‐loading.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1989.tb11301.x

出版商:Wiley    

年代:1989

数据来源: WILEY

摘要:

Immunological affinities were investigated among twenty taxa belonging to the grass subfamilies Pooideae, Chloridoideae, Panicoideae, Oryzoideae, and Bambusoideae. Antisera were raised to the prolamin fraction of seed proteins from species of eleven grass genera (Hordeum, Bromus, Festuca, Phleum, Elensine, Panicum, Pennisetum, Tripsacum, Dendrocalamus, andOryza) and reacted with their homologous antigens and nineteen different heterologous antigens in Enzyme‐Linked Immunosorbent Assay (ELISA). The immunological cross‐reactivity among the eleven taxa whose prolamin was used for antisera production was analyzed quantitatively by generating matrices of averaged cross‐reactivities,Qcorrelation and distance. The averaged cross‐reactivity matrix was calculated from averaging reciprocal immunological reactions while the two other matrices were computed by considering each antiserum as a character and antigens as OTUs. The three matrices were subjected to clustering by the Unweighted Pair Group Method using Arithmetic Averaging (UPGMA). The phenogram based on the averaged similarity matrix showed some distortion, while the other two phenograms were similar in topology and were informative. A phenon line atr= 0.17 divided the phenogram based onQcorrelation into four major groups: Pooideae, Oryzoideae, Bambusoideae, and Chloridoideae‐Panicoideae. The two subfamilies in the Chloridoideae‐Panicoideae group clustered at a correlation coefficient of 0.22. Within the Pooideae, the tribes Aveneae and Agrostideae were closely grouped together (r= 0.85), but they were quite distinct (r= 0.16) from the tightly clustered (r= 0.84–0.85) Bromeae, Poeae, and Triticeae. The Oryzoideae and Bambusoideae showed low immunological similarity (r= –0.07). The two tribes of the Panicoideae, Paniceae and Andropogoneae, displayed extensive immunological similarity clustering tightly atr= 0.84–0.86. The immunological data revealed a possible trend in grass evolution encompassing the chloridoid‐panicoid groups and provided insights into the phylogenetic affinities of the bambusoid and oryzoid grasses. The results also underscored the heterogeneity of the taxa within the Pooideae.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1989.tb11302.x

出版商:Wiley    

年代:1989

数据来源: WILEY

摘要:

Plants from threeLobelia cardinalispopulations were grown under common garden conditions to assess intra‐ and interplant variation in seed and pollen production. Seed number per flower and mean seed weight varied systematically with floral position on the inflorescence (lowest values were from terminal flowers) but pollen grain number per flower did not vary systematically with floral position. Most of the remaining variance in seed and pollen grain number per flower and mean seed weight was distributed among plants; clones produced very similar amounts of pollen and seed. Seed yield was positively correlated with seed production per flower and with total flower production, but not with mean seed weight; pollen yield was also positively correlated with pollen grain production per flower and total flower production. Seed and pollen yield were simple linear functions of plant size but only pollen yield was a simple linear function of flower production; seed yield was a quadratic function in which the second order term was negative. This quadratic relationship resulted from a negative correlation between seed number per flower and total flower production. This correlation, in addition to the wide variation among plants in pollen number per flower, accounts for the weak correlation of seed and pollen yield. I conclude from these data that it is unlikely that plants in naturalL. cardinalispopulations transmit genes to the population's seed crop equally through pollen and ovules—emphasizing the importance of measuring both male and female components of reproductive success.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1989.tb11303.x

出版商:Wiley    

年代:1989

数据来源: WILEY

摘要:

As part of an electrophoretic study onIsoëtes, a number of Neotropical and North American species were examined for allozyme variation in TPI. Three of these species—I. storkii, I. flaccida, andI. mexicana—exhibit three distinct zones of TPI activity. The two most anodally migrating zones are comparable to the two zones found in most angiosperms and in several other species ofIsoëtes.The single or three‐banded phenotypes produced at these loci correspond, respectively, to the homozygous and heterozygous patterns typical of a dimeric enzyme. The most cathodal zone (zone III) differs in producing either single or two‐banded phenotypes. Analyses of these three zones indicate a nearly perfect correlation between zones II and III in putative allelic constitution and relative allelic mobility. Explanations involving TPI gene duplications and/or null alleles fail to account for the peculiar banding characteristics and origin of activity zone III. An alternative hypothesis involving a protease duplication and differential post‐translational modification is postulated. This hypothesis adequately explains the zone III phenotypes and fixation of the third activity zone in the species examined. Amino acid sequencing is suggested as the most direct test of this hypothesis. The taxonomic distribution of TPI III generally supports a previous, morphologically‐based, hypothesis on species relationships inIsoëtes.The presence of this zone is regarded as an independent synapomorphy for a major clade of NeotropicalIsoëtes.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1989.tb11304.x

出版商:Wiley    

年代:1989

数据来源: WILEY

摘要:

The growth and survivorship of a population ofImpatiens capensiswere followed in eastern Nebraska. Soil cores were taken within the population to estimate the size of the seed bank. The number of seeds in the soil remained relatively constant from April through October, with a mean of 200 seeds/m2. The seed bank size corresponded to observed seedling densities in the following years. Twenty permanent plots were established within the population and censused for three years, 1983–1985. Seedling recruitment to the population was similar in 1983 and 1984 but 30% higher in 1985. The seedling densities of plots were uncorrelated from year to year. Survivorship in 1983 followed a Deevey Type I pattern. Almost one‐third of the population survived until chasmogamous reproduction. Plant size (stem height) was measured monthly on all individuals during 1983. The frequency distribution of stem height was positively skewed as long as growth was exponential. When the growth rate slowed, the distribution became more normal.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1989.tb11305.x

出版商:Wiley    

年代:1989

数据来源: WILEY

摘要:

Variation in pollen production was measured within five hermaphrodite species of bromegrass (Bromus). Anther length is an excellent predictor of pollen production in this genus (R2= 0.97). Anther length varied considerably within each of the species, both among and within individual plants. Within plants, most of the variation occurred among florets within spikelets; florets in upper spikelet positions were smaller and produced less pollen. InB. inermis, pollen production was decreased by defoliation and increased in shoots that grew on thatching ant (Formica obscuripes) mounds. Whole‐shoot pollen yield was determined by spikelet number, number of florets per spikelet, and pollen production per floret. All of these yield components must be considered in attempts to estimate pollen production accurately.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1989.tb11306.x

出版商:Wiley    

年代:1989

数据来源: WILEY

摘要:

A comparative growth study was conducted on juice vesicles cultured in the form of various fruit explant types (equatorially bissected fruit halves, longitudinally bissected fruit halves, one‐eighth sections of fruit, one‐quarter sections of fruit, whole carpel segments, 2 or 3 mm thick equatorial slices of fruit, and 1 cm2fruit endocarp pieces) from 15 mm diamCitrus limon(L.) Burm. f. cv. Eureka lemons. Juice vesicles within equatorial fruit halves produced the least amount of callus. Furthermore, these juice vesicles grew similarly to juice vesicles occurring in the tree grown fruit. A study of cultured equatorial fruit halves using 10–45 mm diam lemons was then conducted. Fruit half cultures containing juice vesicles could be readily established from 15–45 mm diam lemons. Vesicles from 10 mm diam fruit halves, however, invariably produced callus. Vesicles cultured within fruit halves produced proportionately less callus as their fruit diam increased. Juice vesicles cultured in 15–30 mm diam fruits lost their original green color and turned opaque as they matured (i.e., after 3–6 months in culture). A method is also presented, whereby whole lemon fruits can be established and maintained in vitro. Lemons, 35–45 mm in diam, were the best explant sources for establishing whole fruit cultures. Juice vesicles in whole fruit cultures may remain viable for up to 8 months in culture.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1989.tb11307.x

出版商:Wiley    

年代:1989

数据来源: WILEY