At the core of plant regeneration, temperature and water supply are critical drivers for seed dormancy (initiation, break) and germination. Hence, global climate change is altering these environmental cues and will preclude, delay, or enhance regeneration from seeds, as already documented in some cases. Along with compromised seedling emergence and vigour, shifts in germination phenology will influence population dynamics, and thus, species composition and diversity of communities. Altered seed maturation (including consequences for dispersal) and seed mass will have ramifications on life history traits of plants. Predicted changes in temperature and precipitation, and thus in soil moisture, will affect many components of seed persistence in soil, e.g. seed longevity, dormancy release and germination, and soil pathogen activity. More/less equitable climate will alter geographic distribution for species, but restricted migratory capacity in some will greatly limit their response. Seed traits for weedy species could evolve relatively quickly to keep pace with climate change enhancing their negative environmental and economic impact. Thus, increased research in understudied ecosystems, on key issues related to seed ecology, and on evolution of seed traits in nonweedy species is needed to more fully comprehend and plan for plant responses to global warming.

Summary Trait‐based approaches have improved our understanding of plant evolution, community assembly and ecosystem functioning. A major challenge for the upcoming decades is to understand the functions and evolution of early life‐history traits, across levels of organization and ecological strategies. Although a variety of seed traits are critical for dispersal, persistence, germination timing and seedling establishment, only seed mass has been considered systematically. Here we suggest broadening the range of morphological, physiological and biochemical seed traits to add new understanding on plant niches, population dynamics and community assembly. The diversity of seed traits and functions provides an important challenge that will require international collaboration in three areas of research. First, we present a conceptual framework for a seed ecological spectrum that builds upon current understanding of plant niches. We then lay the foundation for a seed‐trait functional network, the establishment of which will underpin and facilitate trait‐based inferences. Finally, we anticipate novel insights and challenges associated with incorporating diverse seed traits into predictive evolutionary ecology, community ecology and applied ecology. If the community invests in standardized seed‐trait collection and the implementation of rigorous databases, major strides can be made at this exciting frontier of functional ecology.

The most often used time-line for distinguishing a transient seed bank from a persistent seed bank is one calendar year. Thus, species whose seeds live in or on the soil for <1 year have a transient seed bank, whereas those whose seeds live for ≥1 year have a persistent seed bank. However, dormancy cycling of seeds buried in soil has not been given due consideration in these models. When dormancy cycling is considered, it is shown that seeds of both autumn-germinators and spring-germinators are in the dormant state when they are 1 year old. Thus, unless the seeds live until at least the second germination season (i.e. usually 16–18 months following dispersal), they are, in effect, part of a transient seed bank, having lived through only one germination season. We propose that for seeds of such species to be considered part of a short-term persistent seed bank, they should remain viable and germinable until at least the second germination season, and to be part of a long-term persistent seed bank, until at least the sixth germination season. Our definitions are applicable to seeds with physiological, physical or morphophysiological dormancy, which often require >1 year after maturity to come out of dormancy in nature. We discuss modifications of the seedling emergence method for detection of a soil seed bank, so that they correspond to our definitions of seed-bank strategies.

Relative competitive ability and growth characteristics of the narrow endemic Solidago shortii were compared to those of the geographically widespread S. altissima. Competition and growth studies were conducted over the entire growing season in an ambient-temperature greenhouse, using a 3:1 (v/v) native limestone soil/river sand mixture. Results from a de Wit replacement series experiment (relative yield, relative yield total, plant height, aggressivity values) with S. shortii, S. altissima, and Festuca arundinacea (common competitor) suggested the following competitive hierarchy: S. altissima = F. arundinacea > S. shortii. Using classical growth analysis, we found that the competitive hierarchy was related closely to components of plant size (dry mass, height, leaf area, leaf area duration) and not to relative growth rate or any of its components (net assimilation rate, leaf area ratio, leaf weight ratio, specific leaf area). Solidago shortii allocated proportionately more dry mass to roots (but not to rhizomes) and had significantly greater root/shoot and (root + rhizome)/shoot ratios than did S. altissima. Thus, while the morphological traits of S. shortii enable it to tolerate drier habitats than S. altissima, in moist sites S. shortii easily would be overtopped and shaded out by S. altissima. Low competitive ability may be one of several factors contributing to the narrow endemism of S. shortii.

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Osmorhiza aristata is an herbaceous perennial that grows primarily in Japan, through southern China, to the Himalayas. It closely resembles the eastern North American species O. claytonii and O. longistylis, and, together, the three species are an example of the well-known North American-Asian pattern of disjunction. Requirements for dormancy break and embryo growth were determined for seeds of O. aristata collected in Japan during the summers of 1998-2000. Embryos in fresh seeds were ca. 0.5 mm long, and they had to grow to 9 mm before the radicle emerged from the mericarp. Embryo growth and germination occurred during cold stratification at 5°C, the optimum temperature for germination. Gibberellic acid did not substitute for cold stratification. Thus, O. aristata seeds have deep complex morphophysiological dormancy (MPD). The type of MPD in O. aristata is similar to that in two western North American congeners but different from that in eastern North American congeners (nondeep complex MPD). Mapping the types of MPD onto a phylogeny of the genus suggests that nondeep complex MPD is derived from deep complex MPD. Although eastern North American-Asian disjuncts often exhibit morphological stasis, the taxa may differ greatly in physiological traits, such as seed dormancy.

Osmorhiza Raf. (Apiaceae) consists of 10 species disjunctly distributed in temperate Asia (1 sp.) and the Americas (9 spp.). Osmorhiza berteroi and O. depauperata show an American antitropical disjunction. Within North America, these two species are also disjunctly distributed in eastern and western North America and the Great Lakes regions. A phylogenetic analysis was conducted to clarify inter-and intraspecific relationships based on sequences of the ITS and 5.8S regions of nrDNA. With Anthriscus, Geocaryum, and Myrrhis as outgroups, the monophyly of Osmorhiza is strongly supported. The ITS phylogeny suggests the basal position of the Asiatic O. aristata and the monophyly of the nine New World species. The ITS sequence of Osmorhiza aristata is relatively divergent from those of all other species even though it is morphologically similar to the eastern North American O. claytonii and O. longistylis (which form a clade), suggesting early divergence followed by morphological stasis. Osmorhiza berteroi, O. brachypoda, O. depauperata, O. mexicana, O. occidentalis, and O. purpurea constitute a monophyletic group (ϭ western North American clade). The morphologically distinct O. glabrata from the central Andes forms a trichotomy with the eastern North American clade (O. claytonii and O. longistylis) and the western North American clade in parsimony and maximum likelihood analyses. The 11 populations studied of the widespread O. berteroi form a clade, and showed little sequence divergence, suggesting recent establishment of the widely disjunct populations following long-distance dispersal. Disjunct populations of O. depauperata from the Rocky Mountains and eastern North America have an identical ITS profile. Osmorhiza occidentalis, however, shows a high level of infraspecific sequence divergence. The ITS phylogeny and the low sequence divergence values suggest rapid diversification of Osmorhiza in western North America.