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Summary: Information on seed persistence and seedling emergence from the soil seed bank is critical for understanding species coexistence and predicting community dynamics. However, quantifying seed persistence in the soil is challenging; thus, its association with other life‐history traits is poorly known on a broad scale.Using germination phenology for 349 species in a 42‐yr experiment, we quantified the persistence–emergence correlations and their associations with intrinsic regeneration traits using Bayesian phylogenetic multilevel models.We showed no trade‐off between seed persistence and seedling emergence. Physically dormant seeds were more persistent but exhibited lower emergence than nondormant seeds. Monocarpic species had both higher persistence and emergence than polycarpic species. Seed mass posed a marginal proxy for persistence, while emergence almost doubled from the smallest to the largest seeds.This study challenges the traditional assumption and is the first demonstration of noncorrelation between persistence and emergence, probably owing to the complexity of regenerative strategies. Species with short persistence and low emergence would be the most vulnerable for in situ conservation. Our analyses of this unique, long‐term dataset provide a strong incentive for further experimental studies and a rich data resource for future syntheses. See also the Commentary on this article by Meitzel, 241: 521–522. [ABSTRACT FROM AUTHOR]

Summary: Seed dispersal mechanisms play a crucial role in driving evolutionary changes in seed and fruit traits. While previous studies have primarily focussed on the mean or maximum values of these traits, there is also significant intraspecific variation in them. Therefore, it is pertinent to investigate whether dispersal mechanisms can explain intraspecific variations in these traits.Taking seed size as a case study, we compiled a global dataset comprising 3424 records of intraspecific variation in seed size (IVSS), belonging to 691 plant species and 131 families. We provided the first comprehensive quantification of dispersal mechanism effects on IVSS.Biotic‐dispersed species exhibited a larger IVSS than abiotic‐dispersed species. Synzoochory species had a larger IVSS than endozoochory, epizoochory, and myrmecochory species. Vertebrate‐dispersed species exhibited a larger IVSS than invertebrate‐dispersed species, and species dispersed by birds exhibited a larger IVSS than mammal‐dispersed species. Additionally, a clear negative correlation was detected between IVSS and disperser body mass.Our results prove that the IVSS is associated with the seed dispersal mechanism. This study advances our understanding of the dispersal mechanisms' crucial role in seed size evolution, encompassing not only the mean value but also the variation. [ABSTRACT FROM AUTHOR]

Summary: Early‐stage fitness variation has been seldom evaluated at broad scales in forest tree species, despite the long tradition of studying climate‐driven intraspecific genetic variation. In this study, we evaluated the role of climate in driving patterns of population differentiation at early‐life stages in Pinus sylvestris and explored the fitness and growth consequences of seed transfer within the species range.We monitored seedling emergence, survival and growth over a 2‐yr period in a multi‐site common garden experiment which included 18 European populations and spanned 25° in latitude and 1700 m in elevation.Climate–fitness functions showed that populations exhibited higher seedling survival and growth at temperatures similar to their home environment, which is consistent with local adaptation. Northern populations experienced lower survival and growth at warmer sites, contrary to previous studies on later life stages. Seed mass was higher in populations from warmer areas and was positively associated with survival and growth at more southern sites. Finally, we did not detect a survival–growth trade‐off; on the contrary, bigger seedlings exhibited higher survival probabilities under most climatic conditions.In conclusion, our results reveal that contrasting temperature regimes have played an important role in driving the divergent evolution of P. sylvestris populations at early‐life stages. [ABSTRACT FROM AUTHOR]

Summary: Assumptions about the germination ecology of alpine plants are presently based on individual species and local studies. A current challenge is to synthesise, at the global level, the alpine seed ecological spectrum.We performed a meta‐analysis of primary data from laboratory experiments conducted across four continents (excluding the tropics) and 661 species, to estimate the influence of six environmental cues on germination proportion, mean germination time and germination synchrony; accounting for seed morphology (mass, embryo : seed ratio) and phylogeny.Most alpine plants show physiological seed dormancy, a strong need for cold stratification, warm‐cued germination and positive germination responses to light and alternating temperatures. Species restricted to the alpine belt have a higher preference for warm temperatures and a stronger response to cold stratification than species whose distribution extends also below the treeline. Seed mass, embryo size and phylogeny have strong constraining effects on germination responses to the environment.Globally, overwintering and warm temperatures are key drivers of germination in alpine habitats. The interplay between germination physiology and seed morphological traits further reflects pressures to avoid frost or drought stress. Our results indicate the convergence, at the global level, of the seed germination patterns of alpine species. [ABSTRACT FROM AUTHOR]

Summary: Understanding the dynamics of selection is key to predicting the response of tree species to new environmental conditions in the current context of climate change. However, selection patterns acting on early recruitment stages and their climatic drivers remain largely unknown in most tree species, despite being a critical period of their life cycle.We measured phenotypic selection on Pinus sylvestris seed mass, emergence time and early growth rate over 2 yr in four common garden experiments established along the latitudinal gradient of the species in Europe.Significant phenotypic plasticity and among‐population genetic variation were found for all measured phenotypic traits. Heat and drought negatively affected fitness in the southern sites, but heavy rainfalls also decreased early survival in middle latitudes. Climate‐driven directional selection was found for higher seed mass and earlier emergence time, while the form of selection on seedling growth rates differed among sites and populations. Evidence of adaptive and maladaptive phenotypic plasticity was found for emergence time and early growth rate, respectively.Seed mass, emergence time and early growth rate have an adaptive role in the early stages of P. sylvestris and climate strongly influences the patterns of selection on these fitness‐related traits. [ABSTRACT FROM AUTHOR]

Tall plant species disperse further distances than do short species, within and across dispersal syndromes, yet the driver underpinning this relationship is unclear. The ability of taller plants to invest more in dispersal structures may explain the positive relationship between plant height and dispersal distance. Here, we quantify the cross-species relationships between presence of dispersal structures, dispersal investment plant height and dispersal distance., Plant height, dispersal syndrome and dispersal investment data were collated for 1613 species from the literature, with dispersal distance data collated for 114 species., We find that species with high dispersal investment disperse further than do species with low dispersal investment. Tall species have a greater probability of having dispersal structures on their seeds compared with short species. For species with dispersal structures on their seeds, plant height is very weakly related to dispersal investment., Our results provide the first global confirmation of the dispersal investment-distance hypothesis, and show dispersal investment can be used for predicting species dispersal distances. However, our results and those of previous studies indicate plant height is still the best proxy for estimating species dispersal distances due to it being such a readily available plant trait. [ABSTRACT FROM AUTHOR]

Root traits are often thought to be analogues of leaf traits along the plant economics spectrum. But evolutionary pressures have most likely shaped above- and belowground patterns differentially. Here, we aimed to identify the most important aboveground traits for explaining root traits without an a priori focus on known concepts., We measured morphological root traits in a glasshouse experiment on 141 common Central European grassland species. Using random forest algorithms, we built predictive models of six root traits from 97 aboveground morphological, ecological and life history traits., Root tissue density was best predicted by leaf dry matter content, whereas traits related to root fineness were best predicted by diaspore mass: the heavier the diaspore, the coarser the root system. Specific leaf area ( SLA) was not an important predictor for any of the root traits., This study confirms the hypothesis that root traits are more than analogues of leaf traits within a plant economics spectrum. The results reveal a novel ecological pattern and highlight the power of root data to close important knowledge gaps in trait-based ecology. [ABSTRACT FROM AUTHOR]

Canola (Brassica napus) is a widely cultivated species and provides important resources of edible vegetable oil, biodiesel production and animal feed. Seed development in Arabidopsis and canola shares a similar path: an early proliferation of endosperm to form a large seed cavity, followed by a second phase in which the embryo grows to replace the endosperm. In Arabidopsis, the seed reaches almost its final volume before the enlargement of the embryo. SHORT HYPOCOTYL UNDER BLUE1 (SHB1) is a key regulatory gene of seed development with a broad expression beyond endosperm development. By contrast, its two target genes, MINISEED3 (MINI3) and HAIKU2 (IKU2), are narrowly expressed in early developing endosperm and early embryo. We overexpressed SHB1 in canola to explore the possibility of altering seed development. As an alternative strategy, we expressed the canola IKU2 ortholog in Arabidopsis endosperm under the control of a stronger MINI3 promoter. SHB1 targeted canola orthologs of Arabidopsis MINI3 and IKU2 and caused a significantly increased seed mass. Overaccumulation of IKU2 in the early stage of Arabidopsis seed development also significantly increased the final seed mass. Our studies provide a strong case for increasing the final seed mass by manipulating endosperm proliferation at a rather early developmental stage in crops. [ABSTRACT FROM AUTHOR]

Plant regeneration from seed is largely governed by germinability and speed of germination. These fitness components have received considerably less attention in CO2 research relative to studies of vegetative or reproductive output responses. Moreover, the limited literature has not been rigorously examined for generalizable patterns of responses and/or potential mechanisms. We used a meta-analytic approach to summarize literature results of seed germination characteristics in response to parental CO2 enrichment ( e CO2). The direct effects of e CO2 on germination components were also analyzed. The data set came from 29 original research papers encompassing 64 species and 116 observations. Across all studies, parental e CO2 increased subsequent germination by 9%, but the responses varied among species by as much as 300%. The response was significantly higher in trees than in other life forms. With the exception of crops, parental e CO2 also increased germination rate in most life forms and functional groups. Despite a considerable interspecific variability, we found a positive correlation between germination success and seed mass responses to parental e CO2. Therefore, the observed diversity of regeneration success responses to parental e CO2 is partly controlled by the direction and magnitude of changes in seed mass. [ABSTRACT FROM AUTHOR]

Seed size and dormancy are reproductive traits that interact as adaptations to environmental conditions. Here, we explore the evolution of these traits in environments that differ in overall mean favorability and in the extent of temporal predictability., Our model simulates a population of annual plants living in a range of environments that differ in aridity, namely mean annual precipitation and inter-annual variation of this mean precipitation., The optimal fitness curve is investigated assuming density dependence, three alternative hypothetical relationships between seed mass and seed survival in the soil (negative, positive, and independent of mass), and three alternative relationships between survival in soil and precipitation (strong and intermediate negative relationships, and no relationship)., Our results show that seed size and dormancy are not two substitutable evolutionary traits; that specific combinations of these two traits are selected in environments that differ in favorability and temporal predictability; that a certain degree of seed dormancy is advantageous not only in temporally unpredictable environments but also in temporally predictable environments with high competition; and that more than one combination of seed size and dormancy (defined in terms of germination fraction) can be optimal, even in spatially homogeneous environments, potentially allowing selection for more variation in these traits within and among species. [ABSTRACT FROM AUTHOR]

Contents The evolution of the seed represents a remarkable life-history transition for photosynthetic organisms. Here, we review the recent literature and historical understanding of how and why seeds evolved. Answering the ‘how’ question involves a detailed understanding of the developmental morphology and anatomy of seeds, as well as the genetic programs that determine seed size. We complement this with a special emphasis on the evolution of dormancy, the characteristic of seeds that allows for long ‘distance’ time travel. Answering the ‘why’ question involves proposed hypotheses of how natural selection has operated to favor the seed life-history phenomenon. The recent flurry of research describing the comparative biology of seeds is discussed. The review will be divided into sections dealing with: (1) the development and anatomy of seeds; (2) the endosperm; (3) dormancy; (4) early seed-like structures and the transition to seeds; and (5) the evolution of seed size (mass). In many cases, a special distinction is made between angiosperm and gymnosperm seeds. Finally, we make some recommendations for future research in seed biology. [ABSTRACT FROM AUTHOR]

• Seed size is widely held to exert an important influence over plant establishment, but while large seeds are often assumed to be at an advantage in nutrient-limited conditions, there is in fact, little consistent evidence to support this hypothesis. • Here, we examined the interspecific relationship between seedling growth and seed size for Australian and British Fabaceae species in nutrient solutions deficient in nitrogen, phosphorus, potassium or all nutrients combined (distilled water). • The British species showed no consistent link between mean seed mass and seedling growth in nutrient-limited conditions. By contrast, all four nutrient-deficient treatments yielded a significant relationship for the Australian species. Linear regression showed that growth under balanced nutrient conditions was positively associated with growth without nutrients, although in fewer cases for the British species. • We suggest that habitat-specific differences in regeneration conditions and/or evolutionary history may influence the role that seed size plays in dictating how seedlings of different species respond to nutrient shortage. We recommend caution in attempts to link traits like seed size to wider patterns of plant community ecology. [ABSTRACT FROM AUTHOR]

• Previous investigators have identified strong positive relationships between genome size and seed mass within species, and across species from the same genus and family. • Here, we make the first broad-scale quantification of this relationship, using data for 1222 species, from 139 families and 48 orders. We analyzed the relationship between genome size and seed mass using a statistical framework that included four different tests. • A quadratic relationship between genome size and seed mass appeared to be driven by the large genome/seed mass gymnosperms and the many small genome size/large seed mass angiosperms. Very small seeds were never associated with very large genomes, possibly indicating a developmental constraint. Independent contrast results showed that divergences in genome size were positively correlated with divergences in seed mass. • Divergences in seed mass have been more closely correlated with divergences in genome size than with divergences in other morphological and ecological variables. Plant growth form is the only variable examined thus far that explains a greater proportion of variation in seed mass than does genome size. [ABSTRACT FROM AUTHOR]

Summary • The safe site concept could have utility in community ecology if predictive relationships between plant traits and safe site characteristics could be identified. Here we examine the proposal that the nature and relative abundance of safe sites are systematically related to seed size, in an assemblage of 17 woody species in a temperate forest. • We compared the degree of association of seedlings of each species with elevated microsites, and examined life-history correlates of this variation. • Seed size explained 45% of interspecific variation in percentage of seedlings growing on logs and other elevated substrates. Neither specific leaf area nor an index of light requirements gave significant increases in explanatory power. Phylogenetically independent contrasts gave a similar, but weaker, relationship with seed size. Most small-seeded species were overrepresented on elevated microsites, whereas two large-seeded taxa were underrepresented on these substrates. Safe sites of small-seeded species were therefore more spatially restricted than those of large-seeded taxa, as elevated surfaces occupied only 8% of the forest floor. • Safe site differentiation may help to explain the wide range of seed size present within many communities, as well as species coexistence in forests. [ABSTRACT FROM AUTHOR]

Contents Summary 175 I. Introduction 176 II. Materials and Methods 177 III. Factors underlying the growth response 178 IV. Variation in biomass enhancement ratio 181 V. Functional groups of species 184 VI. The response in a more natural environment 188 VII. An outlook 192 VIII. Conclusions 193 Acknowledgements 193 References 193 Appendices196 Summary The effects of increased atmospheric CO2 concentrations on vegetative growth and competitive performance were evaluated, using five meta-analyses. Paying special attention to functional groups, we analysed responses at three integration levels: carbon economy parameters, vegetative biomass of isolated plants, and growth in competition. CO 2 effects on seed biomass and plant-to-plant variability were also studied. Underlying the growth stimulation is an increased unit leaf rate (ULR), especially for herbaceous dicots. This is mainly caused by an increase in the whole-plant rate of photosynthesis. The increased ULR is accompanied by a decrease in specific leaf area. The net result of these and other changes is that relative growth rate is only marginally stimulated. The biomass enhancement ratio (BER) of individually grown plants varies substantially across experiments/species, and size variability in the experimental populations is a vital factor in this. Fast-growing herbaceous C3 species respond more strongly than slow-growing C3 herbs or C4 plants. CAM species and woody plants show intermediate responses. When grown in competition, C4 species show lowest responses to elevated CO 2 at high nutrient conditions, whereas at low nutrient levels N 2 -fixing dicots respond relatively strongly. No systematic differences were found between slow- and fast-growing species. BER values obtained for isolated plants cannot be used to estimate BER of the same species grown in interspecific competition – the CO 2 response of monocultures may be a better predictor. [ABSTRACT FROM AUTHOR]

It is generally accepted that larger seeds give rise to seedlings with better performance. On the other hand, the size that a seed reaches is genetically determined by at least two different traits; the genetic variability of the developing embryo and the genetic variability of the maternal plant. Thus, the relative contributions of these two traits affect seedling performance by influencing seed size. In this paper, I investigate the effect of seed size on seedling performance in the Scots pine (Pinus sylvestris). From eight maternal plants, 50 seeds were planted in each of two soil types (800 seeds in total), and seedling performance was monitored for 1 yr. Seed mass proved to be highly constant within maternal plants. Soil type influenced emergence and survival; however, the effect of soil type differed depending on maternal origin. Seed mass was positively correlated with seedling emergence, although this relationship was not found for seedling survival or date of emergence. The initial growth of the shoot was also positively correlated with seed mass. However, after one growing season, seed mass had no effect on seedling performance, which depended exclusively on maternal origin. Nevertheless, the mean mass of seeds produced by plants was positively correlated with mean values of growth parameters. Thus, first-year seedling performance seem to be a maternal trait indirectly associated with seed size. [ABSTRACT FROM AUTHOR]

The ability of 16 calcareous grassland species to establish in competition with adult neighbours of two different growth forms was assessed in a glasshouse experiment. The questions asked were: (1) how well is establishment ability related to plant traits such as seed mass, DNA content, relative growth rate and adult height: and (2) are the results consistent across different neighbours? Two measures of establishment ability were calculated, survival relative yield and biomass relative yield, for seedlings grown with a dicot. (Leontodon hispidus) and with a graminoid (Festuca ovina). The results depended on which measure of establishment ability was used. When establishment ability was measured in terms of biomass relative yield, seed mass was a good predictive trait, accounting for 38-55% of variation. However, when establishment ability was measured as survival relative yield, adult height was found to be the best predictor, capable of accounting for 20% of variation, although this was not consistent across neighbours. Thus, no clear relationship between plant traits and establishment ability was found: results depended on the measure of establishment ability used; and in the case of adult height, on the identity of the neighbour species. Survival relative yield was strongly associated with target and neighbour species growth form type, with stronger suppression of like than of non-like growth forms. The lack of strong relationships between plant traits and establishment ability, and the dependence on neighbour identity, suggests that the links between plant traits and establishment might be context-dependent; thus an understanding of the mechanisms underlying any such links is essential. [ABSTRACT FROM AUTHOR]

This paper analysis relationships between relative growth rate (RGR), seed mass, biomass allocation, photosynthetic rate and other plant traits as well as habitat factors (rainfall and altitude) in 20 wild species of Aegilops L. and one closely related species of Amblyopyrum (Juab. & Spach) Eig., which differ in ploidy level (diploid, tetraploid and hexaploid). The plants were grown hydroponically for 20 d in a growth chamber. The relationships between parameters were calculated either using the phylogenetic information (phylogenetically independent contrasts, PIC) or without using the phylogenetic information (trait values or taxa, TIP). The results using the two approaches were very similar, but there were a few exceptions in which the results were different (e.g. RGR vs. seed mass). Specific leaf area (SLA) was positively correlated with leaf area ratio (LAR) and negatively correlated with net assimilation rate (NAR), which together resulted in the absence of a correlation between SLA and RGR. Leaf photosynthetic rates (expressed on a mass or area basis) showed no correlation with RGR. RGR was positively correlated with the stem mass ratio and negatively with root mass ratio. Species with a lower d. wt percentage have a higher RGR. Aegilops species from locations with higher annual rainfall invested less biomass in roots and more in shoots (leaves and stems) and had a higher RGR. Diploid species had a lower seed mass and initial mass than the hybrids (tetraploid and hexaploid species), but there was no correlation of RGR with ploidy level. Polyploid species, which have higher seed mass, occur at a higher altitude than diploid species. Our results show that variation in RGR in Aegilops and Amblyopyrum spp. is associated mainly with variation in biomass allocation (proportion of biomass in stems and root) and d. wt percentage, and not with variation in SLA, leaf photosynthetic rates or seed mass. [ABSTRACT FROM AUTHOR]

We examine the relationship of seed oxygen consumption rate (&Vdot;O2) to seed moisture content, seed mass, and seed age in 22 ecologically diverse tropical species. These seeds vary greatly in moisture content, age, mass, mechanism of dormancy and length of viability. We quantify each relationship with a power equation,&Vdot;O2 = αXb, where X is the independent variable. Seed moisture content (MC) explains 80 % of the variation in mass-specific &Vdot;O2 (ml O2 g-1 h-1 ) among seeds of all species, whereas seed mass explains < 1 %. However, when seeds are reclassified as moist (> 28 % MC) or dry (&les; 28 % MC), seed mass explains 54 % of the variation in mass-specific &Vdot;O2 (ml O2 g-1 h-1) within dry seeds, but no significant variation within moist seeds. In dry seeds, seed age explains only 27 % of the variance in mass-specific &Vdot;O2, although seed age and moisture content are negatively correlated. On a per seed basis, seed mass explains 56 % of the variation in &Vdot;O2 (ml O2 h-1 per seed) in dry seeds and 83 % of the variation in moist seeds: the exponents of the power function, 0·54 in dry seeds and 0·78 in moist seeds, are within the range reported for the allometric relationship of oxygen consumption and body size in animals and prokaryotes. We present a framework for future studies that recognizes seed respiration as an important, yet unstudied, component of tropical seed ecophysiology. We discuss the ecological significance of seed respiration in three groups of tropical species which differ in seed moisture content, mass, viability. [ABSTRACT FROM AUTHOR]

Patterns and causes of inter- and intraspecific variation in individual seed mass were investigated in three prairie and four woodland species of perennial umbellifer. Except for Cryptotaenia canadensis, seeds from woodland species were significantly heavier than those from prairie species. Within species, the magnitude of variation in individual seed mass ranged from three- to 16-fold. All the distributions of individual seed masses for the seven species were significantly leptokurtotic and except for Osmorhiza longistylis, all were significantly skewed. Variation between plants was significant in one prairie species (Oxypolis rigidior) and all woodland species. Mean seed mass in a plant was significantly correlated with plant size in three species. Within plant variation in seed mass accounted for 52-98% of total variation. No one factor consistently affected intraspecific variation in seed mass, although seed number per umbel, timing of umbel production and location of umbel were all important for at least one species. It is postulated that intraspecific variation in seed mass is the rule rather than the exception because of the influence of developmental factors such as seed number, timing of inflorescence production and location of different inflorescences. However, these factors may act in conflicting directions, making it difficult to assign causality to within plant variation in seed mass. [ABSTRACT FROM AUTHOR]

The effects of increased atmospheric CO 2 concentrations on vegetative growth and competitive performance were evaluated, using five meta-analyses. Paying special attention to functional groups, we analysed responses at three integration levels: carbon economy parameters, vegetative biomass of isolated plants, and growth in competition. CO 2 effects on seed biomass and plant-to-plant variability were also studied. Underlying the growth stimulation is an increased unit leaf rate (ULR), especially for herbaceous dicots. This is mainly caused by an increase in the whole-plant rate of photosynthesis. The increased ULR is accompanied by a decrease in specific leaf area. The net result of these and other changes is that relative growth rate is only marginally stimulated. The biomass enhancement ratio (BER) of individually grown plants varies substantially across experiments/species, and size variability in the experimental populations is a vital factor in this. Fast-growing herbaceous C3 species respond more strongly than slow-growing C3 herbs or C4 plants. CAM species and woody plants show intermediate responses. When grown in competition, C4 species show lowest responses to elevated CO 2 at high nutrient conditions, whereas at low nutrient levels N 2 -fixing dicots respond relatively strongly. No systematic differences were found between slow- and fast-growing species. BER values obtained for isolated plants cannot be used to estimate BER of the same species grown in interspecific competition - the CO 2 response of monocultures may be a better predictor. Contents Summary 175 I. Introduction 176 II. Materials and Methods 177 III. Factors underlying the growth response 178 IV. Variation in biomass enhancement ratio 181 V. Functional groups of species 184 VI. The response in a more natural environment 188 VII. An outlook 192 VIII. Conclusions 193 Acknowledgements 193 References 193 Appendices 196.

This paper analyses relationships between relative growth rate (rgr), seed mass, biomass allocation, photosynthetic rate and other plant traits as well as habitat factors (rainfall and altitude) in 20 wild species of Aegilops L. and one closely related species of Amblyopyrum (Jaub. & Spach) Eig., which differ in ploidy level (diploid, tetraploid and hexaploid). The plants were grown hydroponically for 20 d in a growth chamber. The relationships between parameters were calculated either using the phylogenetic information (phylogenetically independent contrasts, PIC) or without using the phylogenetic information (trait values of taxa, TIP). The results using the two approaches were very similar, but there were a few exceptions in which the results were different (e.g. rgr vs. seed mass). Specific leaf area (sla) was positively correlated with leaf area ratio (lar) and negatively correlated with net assimilation rate (nar), which together resulted in the absence of a correlation between sla and rgr. Leaf photosynthetic rates (expressed on a mass or area basis) showed no correlation with rgr. rgr was positively correlated with the stem mass ratio and negatively with root mass ratio. Species with a lower d. wt percentage have a higher rgr. Aegilops species from locations with higher annual rainfall invested less biomass in roots and more in shoots (leaves and stems) and had a higher rgr. Diploid species had a lower seed mass and initial mass than the hybrids (tetraploid and hexaploid species), but there was no correlation of rgr with ploidy level. Polyploid species, which have higher seed mass, occur at a higher altitude than diploid species. Our results show that variation in rgr in Aegilops and Amblyopyrum spp. is associated mainly with variation in biomass allocation (proportion of biomass in stems and roots) and d. wt percentage, and not with variation in sla, leaf photosynthetic rates or seed mass.