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We examined a series of eight pea genotypes differing in three naturally occurring allelic mutations, i.e., af (afila), st (stipules reduced), and tl (tendril-less) and three species, five cultivars, and one interspecific hybrid of tomato differing in SP (SELFPRUNING) allele composition to determine whether different phenotypes ontogenetically express different biomass partitioning patterns compared to the isometric poatitioning pattern and an interspecilic 3/4 scaling 'rule'' governing annual growth with respect to body mass. The slopes and 'elevations' (i.e., a and log [beta], respectively) of log-log linear regression curves of bivariate plots of leaf. stem, and root dry mass and of annual growth vs. total body mass were used to assess pattern homogeneity. The annual growth of all pea and tomato phenotypes complied with the 3/4 growth rule. The biomass partitioning patterns of all tomato phenotypes were statistically indistinguishable from the isometric pattern as were those of the pea wild type and three singlemutant genotypes. However, significant departures from the isometric (and pea wild type) biomass allocation pattern were observed for three genotypes, all of which were homozygous for the af allele. These results open the door to explore the heritability and genetics underlying the allometry of biomass partitioning patterns and growth. Key words: af (afila); allometry; Fabaceae; Lycopersicon esculentum; Lycopersicon pennellii; Lycopersicon pbnpinellifolium; leaf morphology; Piston sativum; scaling relationships; Solanaceae.

The invasive grass Microstegium vimineum grows in low light beneath the canopy of eastern forests in North America by reiteration of modules (phytomers) along a tiller. Basal phytomers are vegetative; terminal phytomers produce a raceme of chasmogamous (CH) spikelets plus an axillary raceme of cleistogamous (CL) spikelets. Additional subterminal phytomers with CL racemes mature basipetally. Allocation to culms, leaves, and CH and CL within phytomers was examined in relation to light conditions for a population in New Jersey, USA. Plants were reared in a greenhouse from seed families of parents in deep shade (2-8% full sun) or sunny, edge habitats. Primary tillers were subdivided into phytomers, dried, and weighed. Tillers from field habitats were similarly treated. For vegetative and subterminal phytomers, allocation to leaves and CH was greatest for the shady habitat. CL allocation decreased from terminal to reproductively immature subterminal phytomers. CH and CL mass was positively correlated with leaf mass, suggesting that reproduction is determined by available photosynthate. CH mass showed a genetic correlation with leaf mass. Developmental plasticity in modular allocation allows Microstegium to maximize fitness when conditions are favorable (e.g., high light along forest edges) by continual maturation of CL caryopses on axillary racemes. Key words: annual grass; chasmogamy; cleistogamy; invasive species; Microstegium vimineum; phytomers; Poaceae.

In this study we explored the effect of the physical environment and the availability of prey (biomass and taxonomic composition) on the patterns of prey capture and reproduction on five populations of Pinguicula moranensis (Lentibulariaceae) in areas ranging from pine-oak forests to desert scrublands. Environmental variation was summarized using principal factor analysis. Prey availability and prey capture increased toward the shadiest, most humid, and fertile population. The probability of reproduction and average bud production per population did not follow the same tendency because both fitness components peaked at the middle of the environmental gradient. These results suggest that the benefits derived from carnivory are maximized at sites fulfilling a trade-off between light, moisture, and prey availability. We also found that the taxonomic composition of both the available prey and that of the prey captured by plants varied among populations. The results also indicated that the prey captured by plants are not a random sample of prey available within populations. Overall, the results from this study revealed a marked amount of heterogeneity in the physical and biotic environment among the populations of P. moranensis, which has the potential to affect the outcome of the interaction between this carnivorous species and its prey. Key words: carnivorous habit; environmental heterogeneity; insectivorous plants; Lentibulariaceae; Pinguicula.

Abundance of invasive plants is often attributed to their ability ot outcompete native species. We compared resource acquisition and allocation of the invasive annual grass Bromus madritensis subsp. rubens with that of two native Mojave Desert annuals, Vulpia octoflora and Descurainia pinnata, in a glasshouse experiment. Each species was grown in monoculture at two densities and two levels of N availability to compare how these annuals capture resources and to understand their relative sensitivities to environmental change. During >4 mo of growth, Bromus used water more rapidly and had greater biomass and N content than the natives, partly because of its greater root-surface area and its exploitation of deep soils. Bromus also had greater N uptake, net assimilation and transpiration rates, and canopy area than Vulpia. Resource use by Bromus was less sensitive to changes in N availability or density than were the natives. The two native species in this study produced numerous small seeds that tended to remain dormant, thus ensuring escape of offspring from unfavorable germination conditions; Bromus produced fewer but larger seeds that readily germinated. Collectively, these traits give Bromus the potential to rapidly establish in diverse habitats of the Mojave Desert, thereby gaining an advantage over coexisting native species. Key words: Bromus madritensis subsp. rubens; desert ephemerals; introduced annual grasses; Mojave Desert; nitrogen uptake; plant biomass; Poaceae; root system; seed production; Vulpia octoflora; water uptake.

Ammophila breviligulata, American beachgrass, and Spartina patens, salt meadow hay, have been grazed by feral horses on the dunes of Assateague Island for hundreds of years; however, because of a significant increase in the horse population since the 1960s, overgrazing and dune erosion have become problems. Grazing was assessed on foredunes of four different morphologies along a 21-km stretch of the Maryland portion of the island using 17 exclosure plot pairs. In addition to decreased cover and biomass of the two species, plant structure was significantly affected by grazing. Leaf length and width, stem diameter, and stem density of A. breviligulata and stem diameter of S. patens were reduced in the grazed plots. Especially sensitive to grazing were reproductive characteristics. Percentage of plants in flower, height of flowering stems, and inflorescence length were all significantly reduced by grazing (nongrazed individuals measured). Species composition was not affected by horse accessibility. Key words: American beachgrass; Ammophila breviligulata; Assateague Island; dune morphology; feral horses; grazing; Poaceae; sand dune; Spartina patens.

We examined the allometry and mechanical properties of the peduncles of Hieracium pilosella and other species in the Asteraceae (H. aurantiacum, Taraxicum officinale, Tragopogon pratensi) to evaluate the hypothesis that tapered, tubular, and non-septate peduncles optimize the trade-offs among stem biomass allocation, elevating flowers and thus their wind-dispersed fruits, and the requirement for a factor of safety against mechanical failure. This hypothesis was evaluated by comparing peduncle morphometry (e.g., biomass M, floral biomass [M.sub.s] and length L) and mechanical properties (e.g., bending rigidity EI) for populations growing in windy and windsheltered sites as well as transplants between sites. Regardless of ambient wind speeds, [M.sub.s] [alpha] [L.sup.4/3] and EI [alpha] [L.sup.11/4) [alpha] [M.sub.s.sup.(5/3)], whereas [M.sub.f]/[M.sub.s] [alpha] [L.sup.-1.15], i.e., peduncles disproportionately increase in their biomass as they increase in length, but mechanically support a disproportionately smaller floral biomass relative to their biomass. Calculations show that the tall peduncles from wind-sheltered sites have a larger fruit dispersal range and a lower factor of safety than the shorter peduncles produced in open sites. These and other observations are interpreted to indicate that tubular peduncles enhance relative fitness in terms of propagule dispersal (but not propagule number per stein) while maintaining a sufficient factor of safety against mechanical failure. Key words: allometry; Asteraceae; Brazier buckling; flexural stiffness; fruit dispcrsal; Hieracium pilosella; plant biomechanics; winding loading.

Gynodioecy is a breeding system in which hermaphrodites coexist with male steriles. Theoretical models predict that without any compensation in female fitness male steriles will disappear from a population due to their reproductive disadvantage. In the present study I investigated whether male-sterile (MS), partially male-sterile (IN), and hermaphroditic (H) plants of Plantago lanceolata differed in reproductive growth and allocation. Offspring of three interpopulation crosses segregating all three sex morphs were grown under nitrogen-limited conditions in a growth chamber. Independent of the genetic background MS plants attained a higher vegetative and reproductive dry mass and a higher reproductive output than H plants, whereas IN plants had intermediate values. When corrected for the mass of the pollen, the dry mass differences between the sex morphs were much reduced but still present. However, when whole-plant allocation was expressed on the basis of nitrogen, the differences between the sex morphs disappeared. Thus the sex morphs took up similar amounts of nitrogen but distributed them differently. The MS and IN plants used the nitrogen saved by not producing pollen for additional vegetative as well as reproductive growth. The data presented in this study suggest that resource compensation is one of the main mechanisms responsible for the maintenance of MS and IN plants in gynodioecious P. lanceolata. Key words: biomass allocation; compensation; gynodioecy; male sterility; Plantaginaceae; Plantago lanceolata; reproductive growth.

Boltonia decurrens (Torrey & Gray) Wood, a perennial species endemic to the Illinois River Valley, is threatened with extinction. Construction of a system of dikes along the Illinois River has altered flood patterns during the last 100 years, converting wet prairies and natural marshes to cropland. Remaining shore habitats have been modified by heavy siltation and altered flooding regimes. Boltonia decurrens is now confined to areas that are disturbed by occasional cropping, disappearing from sites after 3 to 5 years of natural succession. This study was conducted to determine the role of light and water availability upon growth and reproduction. Our data indicate that under greenhouse conditions B. decurrens requires high levels of light for optimal photosynthesis and growth, and is more sensitive to reductions in growth light level than to moderate drought-stress. This sensitivity to light regime may help explain its disappearance from disturbed areas after several years of natural succession. If B. decurrens is overtopped by fast-growing species, it could be shaded to the extent that growth and seed production would be severely affected, increasing the likelihood of its extinction.

The allometry of reproductive biomass M was determined for one moss (Polytrichum commune), four pteridophytes (Psilophyton princeps, Psilotum nudum, Lycopodium lucidulum, and L. clavatum), six gymnosperms (Larix decidua, Pseudotsuga douglasii, Tsuga canadensis, Pinus rigida, Picea abies, and Taxus baccata), and two angiosperms (Crataegus sp. and Quercus bicolor). Biomass M was measured for individual and grouped reproductive organs and regressed as a function of stem diameter D measured proximal to M for representative reproductive stems from each species. Published data for Cooksonia pertoni were used to estimate sporangial M. The data from this vascular plant fossil were compared to those from other species. Least squares regression of the entire data set yielded M = 0.12D(super 2.9) (r squared = 0.94, N = 215), indicating that M, on the average, compiled with M proportional to D(super alpha approximately equal to 3.0). The allometries of the moss, pteridophyte, gymnosperm, and angiosperm species, however, were M = 0.46D(super 4.6) (r squared = 0.99, N = 41), M = 0.07D(super 3.2) (r squared = 0.91, N = 65), M = 0.56D(super 2.2) (r squared = 0.92, N = 85), and M = 0.44D(super 1.8) (r squared = 0.97, N = 21), respectively, indicating that the proportionality M is proportional to D(super alpha approximately equal 3.0 recedes with finer taxonomic resolution. The data for Cooksonia were found to comply with the allometry of Polytrichum when the regression curve of this moss was extrapolated into the size range of the fossil species. Analyses showed that intraspecific allometric scaling factors alpha were dependent upon the manner in which plant stems taper. Species or portions of branching systems with alpha > 4.0 had essentially untapered stems (e.g., Polytrichum commune, Psilotum nudum, twigs of Larix decidua); species with alpha < 2.2 had tapered stems resulting from secondary growth in most cases. The evolution of tapered primary stems and secondary growth was interpreted to alter reproductive allometry.

A sequential coring approach was used to measure root biomass and production over 1 year in four different communities within the Great Dismall Swamp. A second method, an implanted bag technique, was also used to measure root production, and values were generally lower using this technique. On all sites, fine roots were the most dynamic root component. Both biomass (1,887 g/[m.sup.2]) and production (354-989 g [m.sup.-2] [yr.sup.-1]) were highest on the mixed hardwood site, the least flooded site, and second highest on the cedar site, the site with the longest duration of soil saturation (1,033 g[m.sup.2] and 274-366 g [m.sup.-2] [yr.sup.-1). The maple-gum (696 g/[m.sup.2] and 59-91 g [m.sup.-2 yr.sup.-1) and cypress (824 g/[m.sup.2] and 68-308 g [m.sup.-2] [yr.sup.-1) sites had similarly low amounts of biomass and rates of production. Environmental parameters that influenced production include frequency and duration of flooding, and soil type. Peaks in belowground production were observed on the most productive sites (mixed hardwood and cedar) in summer and late fallwinter; the other two sites exhibited little seasonal variability. The least flooded stand appears to allocate a greater percentage of net primary production belowground than the more extensively flooded stands. The ratio of above- and belowground allocation appears to change in response to a flooding gradient. This has major implications for ecosysten functions as carbon allocation patterns determine the array of litter types generated (leaves vs. roots) which affect decomposition rates and nutrient availability.

Populations of Atriplex triangularis were grown under laboratory conditions in a growth chamber and manipulated in an inland Ohio saline pond in order to examine the relative effects of salinity, nitrogen fertilization, and population density on growth, reproduction, and survival. For laboratory plants, nitrogen fertilization was the most important variable, with biomass and reproductive effort being greatest at the high nitrogen level. As salinity increased, biomass decreased only in plants greatest at the high nitrogen level. As salinity increased, biomass decreased only in plants not limited by nitrogen. Increasing density caused biomass per plant to decrease at both high and low nitrogen levels. For field plants, density was the most important variable, with biomass per plant and survival both decreasing as density increased. As density increased, size inequality among individuals increased but biomass per unit area and individual reproductive effort remained relatively constant. Nitrogen fertilization slightly enhanced survival, but did not affect biomass. It is suggested that density-dependent processes may be significant even in relatively harsh physical environments.

The two species of Typha common in the southeastern United States, T. latifolia and T. domingensis differ substantially in their tolerance to deep water. The objective of this study was to examine the morphology and biomass allocation of these two species to determine if they have similar phenotypic responses to water depth. Replicate monocultures of the two species were established at a range of water depths in an artificial pond and allowed to grow for three growing seasons. At the end of the experiment, subsamples were harvested for determination of plant morphology as well as above- and belowground biomass. Both species of Typha showed increases in maximum height with increasing depth. The species less tolerant to deep water (T. latifolia) allocated more of its biomass to leaves with increasing water depth. In contrast, the deep water species (T. domingensis) showed increased total size of each ramet but a fixed percentage of biomass in leaves with increasing water depth. Both species had a decreasing incidence of flowering and decreasing shoot density with increasing water depth. In general, these species conform to expectations based on considerations of how their carbon budgets would be affected by water depth.

Promotion of fast growing exotic trees chiefly Eucalyptus as monocultures, strip plantations, shelterbelts have raised ecological imbalance in most parts of north-western India. In order to improve soil conditions and the productivity of Eucalyptus, mix-cultures of E. tereticornis with leguminous trees namely Dalbergia sissoo (indigenous) and Prosopis juliflora (exotic) were raised in semi-arid zone. The study involves the evaluation of floristics on the floor of E. tereticornis and P juliflora mix-plantations with that of E. tereticornis and D. sissoo. For consecutive two years, at an interval of three months, floristic components with respect to relative frequency, density, dominance, importance value index and indices of richness, evenness, diversity, dominance, similarity and dissimilarity, of the vegetation in these plantations was surveyed and compared. The results indicate better floristic coposition under the cover of E. tereticornis and D. sissoo mix-culture. Plant diversity and biomass distribution in ground vegetation was found lesser in the mix plantation of exotics (E. tereticornis and P. juliflora) as compared to mixture with the indigenous D. sissoo.

Biomass allocation patterns have received considerable attention from plant ecologists and evolutionary biologists. However, until recently, many theorists and empiricists have ignored the fact that these allocation patterns change during plant growth and development, such that different allocation patterns may result either from flexibility in allocation per se (allocational plasticity) or in overall plant growth (plasticity in growth or developmental rates). In cases where allocational plasticity is strictly due to the latter, much of our current theory concerning optimal growth patterns and functional adaptations of plants to variable environments will need to be revised. Results from my research include: (1) most plant allocational plasticity is a direct result of plasticity in growth rates rather than physiological adjustments; (2) true allocational plasticity has been found for vegetative, but not reproductive, biomass allocation patterns; but (3) these plastic allocational responses are found only in response to variable light and nutrient availability and not in response to variable water and C[O.sub.2] availability; (4) species differ with respect to the amount of vegetative allocational plasticity they can express; and (5) the ability to alter vegetative allocational patterns may be limited to the early stages of growth and development; (6) plasticity in reproductive output is a result of plasticity in growth rates and/or plasticity in rates of development independent of plant size; (7) plasticity in nitrogen allocation and utilization for growth has been found with respect to light but not C[O.sub.2] availability.

Ozone in the range of 47 to 61 ppb (7 hours maximum) and 58 to 71 ppm-hr (sum 0 total exposure) caused decreases in the growth and changes in the crown architecture of ramets from two aspen (Populus tremuloides Michx.) clones differing in ozone sensitivity and grown in the grown in open-top chambers. Among the parameters showing statistically significant negative responses to ozone for both clones were long shoot length, main stem and long shoot diameters, the number of leaves produced on the current terminal and on long shoots, and the ratio of shoot biomass to shoot length. In addition, current terminal length and dry weights of the main stem, branches, and roots were all significantly affected in a negative manner by ozone for the sensitive clone. Significant increases in the angle of termination were detected for both the current terminal and long shoots of both clones at the highest ozone concentration and for the sensitive clone at even the lowest ozone concentration. These results support our previous results suggesting aspen is highly sensitive to ozone; and, for the first time, we report that ozone can also affect crown architecture of aspen.

The response of Inga seedlings to flooding was studied under shade-house conditions using growth analysis techniques. Seeds were germinated on sandy-loam soils in black polyethylene pots. When seedlings were 14 weeks old(from the time of seedling emergence) a population of 40 seedlings were selected for morphological uniformity (identical height, leaf numbers and size). Ten seedlings were randomly selected and destructively harvested for growth analysis (initial harvest). One half each of the remaining 30 seedlings were randomly assigned to control (non-flooding) treatments for 54 days. Flooding was achieved by immersing 3 potted seedlings each in a 30 litre capacity plastic tub with the water level about 1 cm above the potted soil surface. At the end of the 54 days 10 seedlings of each treatment were randomly destructively sampled for growth analysis(final harvest). The remaining seedlings (5) were used for mineral analysis by atomic absorption spectrometry. Flooding increased plant height, plant biomass, leaf biomass and stem biomass by 17%, 25%, 25% and 123%, respectively; but decreased root biomass by 67%, although extensive adventitious roots were formed in flooding seedlings. Flooding did not alter LWR but, decreased RWR and root: shoot ratio by 73% and 79%, respectively, while increasing SWR by 75%. Differences in biomass accretion between treatments were due to plant RGR where flooding increased RGR by 25%. Flooding increased net assimilation rate by 49%. Flooding decreased foliar N, P, K, Mg, Ca by 15%, 70%, 14%, 30% and 91%, respectively. Except for the negative impact of flooding on root biomass and foliar nutrient contents. Inga seedlings exhibit greater biomass accretion under flooding stress.

Traditionally, plant biomass and stem and root length has been used to evaluate the impact of soil contaminants on plant productivity. We compared use of plant biomass vs. reproductive effort as a reliable assay for aluminum toxicity in wild-type Brassica rapa. Seeds obtained from the Crucifer Genetics Center were planted in a commercial potting mix. Soil pH was adjusted from 7.0 to 6.0, 5.5, 5.0, and 4.5. Treatments were paired by pH level and 1.248 g Al[(OH).sub.3]/I soil added to one member of each pair. Vegetative features quantified included pre- and post-reproductive biomass and stem length. Reproductive effort was evaluated using pollen stainability, pollen and ovule counts, and P/O ratios. Data was analyzed using ANOVA. Preliminary results indicate that the response of Brassica rapa to pH and available aluminum is complex and a linear relationship between productivity and available aluminum may not exist.