Plant traits—the morphological, anatomical, physiological, biochemical and phenological characteristics of plants—determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait‐based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits—almost complete coverage for ‘plant growth form’. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait–environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives.

The current knowledge of the physiological ecology of vascular epiphytes is reviewed here with an emphasis on the most recent literature. It is argued that by far the most relevant abiotic constraint for growth and vegetative function of vascular epiphytes is water shortage, while other factors such as nutrient availability or irradiation, are generally of inferior importance. However, it is shown that the present understanding of epiphyte biology is still highly biased, both taxonomically and ecologically, and it is concluded that any generalizations are still preliminary. Future studies should include a much wider range of taxa and growing sites within the canopy to reach a better understanding how abiotic factors are limiting epiphyte growth and survival which, in turn, should affect epiphyte community composition. Finally, a more integrative approach to epiphyte biology is encouraged: physiological investigations should be balanced by studies of other possible constraints, for example, substrate instability, dispersal limitation, competition or herbivory.

Epiphytes make up roughly 10% of all vascular plant species globally and play important functional roles, especially in tropical forests. However, to date, there is no comprehensive list of vascular epiphyte species. Here, we present EpiList 1.0, the first global list of vascular epiphytes based on standardized definitions and taxonomy. We include obligate epiphytes, facultative epiphytes, and hemiepiphytes, as the latter share the vulnerable epiphytic stage as juveniles. Based on 978 references, the checklist includes >31,000 species of 79 plant families. Species names were standardized against World Flora Online for seed plants and against the World Ferns database for lycophytes and ferns. In cases of species missing from these databases, we used other databases (mostly World Checklist of Selected Plant Families). For all species, author names and IDs for World Flora Online entries are provided to facilitate the alignment with other plant databases, and to avoid ambiguities. EpiList 1.0 will be a rich source for synthetic studies in ecology, biogeography, and evolutionary biology as it offers, for the first time, a species‐level overview over all currently known vascular epiphytes. At the same time, the list represents work in progress: species descriptions of epiphytic taxa are ongoing and published life form information in floristic inventories and trait and distribution databases is often incomplete and sometimes even wrong. Since the epiphytic growth blends into soil‐rooted growth and vice versa, the inclusion or exclusion of particular species in the current list will sometimes be contentious. Thus, initiating a well‐founded discussion was one of the motivations for compiling this database; our list represents 31,311 hypotheses on the life form of plant species, and we welcome feedback on possible omission or erroneous inclusions. We release these data into the public domain under a Creative Commons Zero license waiver. When you use the data in your publication, we request that you cite this data paper. If EpiList 1.0 is a major part of the data analyzed in your study, you may consider inviting the EpiList 1.0 core team as collaborators.