Facing the current biodiversity crisis, the value of ex situ conservation has been increasingly acknowledged in international treaties and legislations. Seed banks are a good way of conserving biodiversity, providing that seeds are of high quality and at maximum viability. However, despite the number of established ex situ facilities, there is little information on seed viability in botanic garden seed banks. This paper analyses the status of the seed collection of the National Botanic Garden of Belgium by determining the germination capacity and viability of seeds that have been stored for 1-26 years. It aims at:(1) ensuring that existing storage conditions provide effective ex situ conservation of threatened species; (2) providing viability data on threatened species; (3) planning future collection and storage efforts for seeds of West European species of conservation value. Results from this study showed that the germination and viability percentages of the 250 tested species reached on average 59 and 79% respectively. Some families typically performed better than others. Within a species, consistent results were not always obtained. Over a quarter of accessions exhibited some degree of dormancy. Considering the current lack of knowledge in seed germination and dormancy of many rare and threatened species, we believe that the quality of a seed collection should be estimated by its viability and not by its germination percentage. This study calls for further research in order to better understand the biology of a range of threatened native species.

Changes in life‐history traits such as seed dormancy during cultivation of wild plant species in ex situ facilities could jeopardize conservation actions including revegetation and plant reintroductions, but the magnitude of these risks and their spread across different plant taxa is unknown. We explored whether plants cultivated in the Botanic Garden Meise differ in seed germination characteristics from plants from natural populations. Using a Bayesian approach of a phylogenetically informed generalized linear mixed model, we analysed germination tests of 72 herbaceous plant species from 27 plant families, originating from the cultivation beds in Meise as well as directly from wild populations. We investigated whether garden‐collected seeds differ in germination percentage, seed dormancy and germination speed from wild‐collected seeds. Furthermore, by analysing literature‐collected information of 24 life‐history traits, we sought to identify potential selection pressures causing these germination changes in order to refine conservation protocols and practices. We found a strong increase of germination percentage and a loss of seed dormancy in garden seeds compared to wild seeds across all species. However, these differences vanished with increasing storage time of the seeds as a result of decreased seed viability with seed ageing over time. Furthermore, traits associated with the life span of the species influenced the germination difference between cultivated and wild seeds, and short‐lived species were particularly vulnerable to the loss of dormancy, while no difference could be detected between wild and cultivated perennial species. Synthesis and applications. Through a multispecies approach, we show that dormancy loss is a common phenomenon in ex situ collections of short‐lived wild plant species. This has wide implications for the use and procedure of ex situ‐reared plant material for restoration and reintroduction measures. We suggest that effective dormancy breaking and temporal distribution of seedling plantation during propagation should be incorporated in restoration and reintroduction protocols to minimize unwanted changes in seed traits. Furthermore, we caution against the use of seeds from cultivated plants for basic seed ecology research such as germination requirements and seed storage behaviour.

Plant collections in herbaria are potentially valuable seed sources for conservation and recovery. This paper explores the feasibility of "resurrecting" 26 extinct taxa from the Belgian flora by analysing the viability of seeds from old herbarium specimens that had been stored for 23 to 158 years. Seed viability was estimated by performing germination tests according to standard procedures. Germination was achieved for eight seeds from three herbarium specimens of a single species, Bupleurum tenuissimum, aged 101, 125 and 144 years. Seed maturity, storage conditions and seed senescence were the main factors influencing the viability of the investigated seeds.

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