Epiphytic Habit Research Articles

Habitat diversity promotes and structures orchid diversity and orchid-host tree interactions

At the regional scale, abiotic environmental heterogeneity related to elevation and climatic profiles influences patterns of diversity and species composition. At the local scale, little is known about the influence of biotic environmental heterogeneity (habitat diversity) on the diversity, composition, and networks of interspecific interactions (epiphyte-host tree) of plant families with species of epiphytic and terrestrial habit. As a study model, we selected the orchids of a tropical landscape in central Veracruz, Mexico, which comprises natural habitats of tropical oak forest (TOF), semi-humid deciduous forest (SDF), and tropical dry forest (TDF), as well as shaded coffee plantation (SCP). In this landscape, we recorded a total of 635 individual orchids, belonging to 51 species (80% of epiphytic habit). The TOF and SDF, with 36 and 30 orchid species, respectively, were at least twice as diverse than TDF and SCP, and also presented greater similarity in terms of species composition. The TDF presented a particular composition of orchids comprising species that are morphologically adapted to conditions of drought, and also presented more species of terrestrial habit than the other habitats. The SCP hosted a subset of the species of TOF. The structure and specialization of the network of orchid-host tree interactions (at the landscape level) was less nested, and more modular and specialized than has been reported previously for commensalist networks of vascular epiphytes. The most abundant and tallest tree species favored the orchid-host tree interactions. For this reason, at the landscape scale, the particular tree community of different habitats promotes the great diversity and acts to structure the composition and interactions of one of the most representative plant families of the Neotropics.

Spatial turnover of fungi and partner choice shape mycorrhizal networks in epiphytic orchids

Abstract In soils, plants and fungi can form complex mycorrhizal networks allowing nutrient transfers between plant individuals and species. It is less clear, however, whether such networks exist on the bark of trees where epiphytic plant communities thrive in rainforests. Previous work showed that tropical epiphytic orchids especially, harbour symbiotic fungi in their roots, but the structure and determinants of the resulting networks remain unknown at the tree scale. We tested the hypothesis that epiphytic orchids rooted in the same area on the bark share mycorrhizal fungi, regardless of their species (i.e. spatial determinant). For this purpose, we selected the trunk of six trees of two common species in a rainforest and sampled orchid roots, protocorms and surrounding bark. We identified mycorrhizal fungi including Tulasnellaceae using high‐throughput sequencing of the ITS2 marker, and reconstructed orchid–fungus bipartite networks for each tree to analyse their structure and the spatial turnover of this symbiosis. We found that epiphytic orchid communities form antinested and highly modular networks with mycorrhizal fungi spread on the bark. As expected, modules of interactions are explained by their spatial structure, with nearby roots sharing fungi, but also by the orchid species involved. These results reveal the presence of shared mycelial networks in epiphytic habitats, whose roles in the resilience and facilitation of epiphytic plant communities need to be assessed. Synthesis. Tropical tree barks are densely colonized by certain mycorrhizal fungi that can form symbioses in nearby adult and young orchids simultaneously. These mycorrhizal networks may allow water and nutrient transfers to alleviate the stressful conditions of the epiphytic habitats.

The genome of Aechmea fasciata provides insights into the evolution of tank epiphytic habits and ethylene-induced flowering

Aechmea fasciata is one of the most popular bromeliads and bears a water-impounding tank with a vase-like rosette. The tank habit is a key innovation that has promoted diversity among bromeliads. To reveal the genomic basis of tank habit formation and ethylene-induced flowering, we sequenced the genome of A. fasciata and assembled 352 Mb of sequences into 24 chromosomes. Comparative genomic analysis showed that the chromosomes experienced at least two fissions and two fusions from the ancestral genome of A. fasciata and Ananas comosus. The gibberellin receptor gene GID1C-like was duplicated by a segmental duplication event. This duplication may affect GA signalling and promote rosette expansion, which may permit water-impounding tank formation. During ethylene-induced flowering, AfFTL2 expression is induced and targets the EIN3 binding site ‘ATGTAC’ by AfEIL1-like. The data provided here will serve as an important resource for studying the evolution and mechanisms underlying flowering time regulation in bromeliads.

Revisiting R.H. Tschudy’s fern-spore spike concept 40 years later: connecting Tschudy’s ‘disaster taxon’ concept with paleopolyploidization in Stenochlaena J. Sm

The Cretaceous/Paleogene (K/Pg) boundary fern-spore spike concept was first introduced by R.H. Tschudy 40 years ago and established the precept that ferns are so-called ‘disaster taxa’ that flourish after natural disasters because of the high colonization potential of their wind-blown spores. Among the least understood topics at the crux of contemporary K/Pg boundary fern-spike studies is whether Stenochlaena-like or other stem blechnaceous ferns were among those that flourished after the K/Pg event, contributing to the Laevigatosporites-dominated phase of the fern-spore spike. For instance, dispersed Stenochlaena-like spores – e.g. Polypodiisporites usmensis (van der Hammen) Khan & Martin – first appear in the upper Eocene stratigraphic record of South America, whereas megafossils of Stenochlaena-like ferns are first known from the upper Paleocene strata of this same region. Beyond this traditional focus on taphonomic and taxonomic uncertainty regarding the identity of dispersed spore producers, however, there is further discordance between contemporary paleobotanical and molecular phylogenetic perspectives on the timing of diversification of stem lineages of blechnaceous ferns in relation to the K/Pg boundary. This investigation reconciles these two perspectives by constraining molecular clock divergence time estimates using contemporary fossil data. If this reconciliation is correct, then paleopolyploidization (whole genome duplication or WGD) associated with the origin of the genus Stenochlaena J. Sm. predated evolution of polocytic stomata, a heavily ornamented exospore, and a hemi-epiphytic to epiphytic habit observed in the crown lineage. Critically, this novel perspective elicits a merger of the K/Pg boundary fern spike and K/Pg boundary-WGD concepts, suggesting a link between polyploidy and the ‘disaster taxon’ concept.

Two new species of Drymonia (Gesneriaceae) from Northwestern South America, including the discovery of the longest flower known in the genus.

Two new species, Drymoniaintermedia Clavijo & J.L.Clark, sp. nov. and D.longiflora J.L.Clark & Clavijo, sp. nov. (Gesneriaceae, Columneinae), are described from the western Andean slopes of Ecuador and Colombia. The new species are similar to D.fimbriata, D.laciniosa, D.macrophylla, and D.peponifera because of the facultative epiphytic habit, deeply serrate to laciniate calyx margins, and fleshy bivalved capsules with tardily dehiscent endocarps. Leaves with brochidodromous venation, narrowly elongate corolla tube, and laciniate calyx margins differentiate D.intermedia. The longest corolla of any known Drymonia (> 6.5 cm long) differentiates D.longiflora. Digital photographs, geographic distributions, and IUCN categories are provided for the new species.

Diversification Slowdown in the Cirrhopetalum Alliance (Bulbophyllum, Orchidaceae): Insights From the Evolutionary Dynamics of Crassulacean Acid Metabolism.

Evolutionary slowdowns in diversification have been inferred in various plant and animal lineages. Investigation based on diversification models integrated with environmental factors and key characters could provide critical insights into this diversification trend. We evaluate diversification rates in the Cirrhopetalum alliance (Bulbophyllum, Orchidaceae subfam. Epidendroideae) using a time-calibrated phylogeny and assess the role of Crassulacean acid metabolism (CAM) as a hypothesised key innovation promoting the spectacular diversity of orchids, especially those with an epiphytic habit. An explosive early speciation in the Cirrhopetalum alliance is evident, with the origin of CAM providing a short-term advantage under the low atmospheric CO2 concentrations (pCO2) associated with cooling and aridification in the late Miocene. A subsequent slowdown of diversification in the Cirrhopetalum alliance is possibly explained by a failure to keep pace with pCO2 dynamics. We further demonstrate that extinction rates in strong CAM lineages are ten times higher than those of C3 lineages, with CAM not as evolutionarily labile as previously assumed. These results challenge the role of CAM as a “key innovation” in the diversification of epiphytic orchids.

Leaf structural adaptations in vascular epiphytes from the Atlantic rainforest along phorophyte vertical stratification

Epiphytes are constantly exposed to light, water and nutrient stress, and thereby they frequently show anatomical adaptations in response to their habit. We aimed to investigate the variation in foliar anatomical traits of epiphytes along vertical stratification. We hypothesized that different species from varied groups would show a variation in foliar anatomical traits that would reflect the variation in microclimatic variables found across phorophyte strata. To address our hypothesis, we studied 23 vascular epiphyte species from different groups (ferns, magnoliids, monocots, and eudicots), occurring on ten phorophytes from a trail at an Atlantic Rainforest fragment in southeastern Brazil. We measured six microclimatic parameters at different phorophyte heights: light intensity, temperature, relative air humidity, altitude, evaporation rate, and wind speed. We then collected expanded-leaf samples for quantitative and descriptive anatomical evaluation, seeking to detect possible correlations between structural traits and microclimatic variations. We found that overall the analyzed species showed pronounced xeromorphic characters in response to epiphytic habit, such as thick outer periclinal wall of pavement cells, lignified epidermis, multiseriate epidermis, stomata below the level of pavement cells, water-storing tissues, and parenchymatous cells with wall thickenings, among others. In most epiphytes, we also found a trend for thicker mesophyll in plants exposed to higher light intensity along different phorophyte strata. The ecophysiological significance of these adaptations is discussed in detail. Our hypothesis was accepted, since we found that species from different groups showed a variation in foliar characters that reflected the variation found in microclimatic parameters along phorophyte strata. Some anatomical traits, e.g. thick mesophyll, were influenced by height differences along phorophytes and by the consequent variation in light intensity along vertical stratification, while other traits were directly related either to the epiphytic habit, especially to the water and nutrient deficits imposed by it, or to the taxonomic group, as seen in ferns.

Context-Dependent Benefits of Aphids for Bacteria in the Phyllosphere.

AbstractInsect herbivores, such as aphids, are common on plants, yet how they interact with plant microbiomes remains largely unknown. For instance, for the widespread bacterial epiphyte and potential aphid pathogen Pseudomonas syringae, aphids could impact bacterial populations by serving as secondary hosts or by altering the epiphytic habitat through feeding and/or waste secretion. Here, we examined whether the pea aphid, Acyrthosiphon pisum, could influence epiphytic populations of P. syringae. First, we quantified epiphytic growth ability without aphids and virulence to aphids across 21 diverse P. syringae strains. For eight strains that varied in these traits we then assessed the influence of aphid presence on epiphytic bacterial growth. In some cases P. syringae benefited significantly from the presence of aphids, with up to 3.8 times more cell doublings. This benefit was not correlated with strain traits but rather with initial population densities; smaller bacterial populations received relatively more benefit from aphids, and larger populations received less benefit. Honeydew, the sugary waste product of aphids, in the absence of aphids was sufficient to increase P. syringae density on leaves. We conclude that aphid honeydew can sometimes increase P. syringae epiphytic growth but that the bacteria may not benefit from using aphids as hosts.

The epiphytic bryophyte succession of Picea orientalis forests on the Kumbet High Plateau (Giresun-Turkey)

In this study, the epiphytic bryophyte succession of Picea orientalis forests on the K?mbet High Plateau (Giresun-Turkey) were studied. A total of 21 epiphytic bryophyte species were determined (16 mosses and 5 liverworts). The epiphytic bryophyte communities were sampled in 60 sample plots taken from the trunks of Picea orientalis, each of which was 20 ? 20 cm in size. The Index of Ecological Significance (IES), based on a combination of the relative frequency and mean cover of epiphytic bryophytes, was used to evaluate the abundance of bryophyte communities in epiphytic habitats on the tree trunks. In addition, multivariate classification techniques (TWINSPAN and DECORANA) were used to classify the community structures in successional stages. TWINSPAN divided the 60 sample plots into two main groups: a) the lower base communities (LB) and b) the middleupper zone communities (MU). Moreover, the middle-upper zone communities (MU) were divided into two sub-groups associated with the successional gradient (MU1 and MU2). DECORANA classified these communities along the ordination axes 1 and 3 related to the height gradient of Picea orientalis and the moisture (from mesic to xeric) gradient of the epiphytic habitat. While Exsertotheca crispa, Cynodontium fallax, Lewinskya striata, and Habrodon perpusillus were only found on old spruce trees, Drepanium fastigiatum was only found on young trees and Lophocolea heterophylla was only found on middle-aged trees.

ETLINGERA COMOSA, A NEW SPECIES (ZINGIBERACEAE: ALPINIOIDEAE) FROM CENTRAL SULAWESI

ARDIYANI, M., ARDI, W. H., HUTABARAT, P. W. K. & POULSEN, A. D. 2021. Etlingera comosa, a new species (Zingiberaceae: Alpinioidea) from Central Sulawesi. Reinwardtia 20(2): 63−68. — Etlingera comosa Ardiyani & Ardi, a new and unusual species from Tentena, Central Sulawesi exhibiting terrestrial as well as epiphytic habit is described here. It is compared to the morphologically closest Etlingera sublimata A.D.Poulsen, but differs in having tufted sheath, bilobed and asymmetric ligule, loose peduncular bracts, densely pubescent fertile bracts and longer filament. Colour plates, notes on its conservation status and DNA barcode data for the new species are also provided.

Diversity of mosses in some underexplored regions of Manipur, Northeast India

The present paper deals with the investigation of moss taxa of some underexplored regions of Manipur, Northeast India. During the assessment of moss diversity in various localities of Manipur a total 126 species of mosses belonging to 84 genera in 34 families have been investigated and enumerated. Ten species, namely Amblystegium serpens,Entodontopsis leucostega, Entodontopsis tavoyensis, Homalia trichomanoides, Lindbergia duthiei, Philonotis mollis, Philonotis thwaitesii, Taxiphyllum giraldii,Tortella humilis and Thuidium sparsifolium are new additions to Eastern Himalaya, while 92 species of mosses have been reported for the first time from Manipur. Ten Indian endemic taxa have also been identified from the explored sites. The majority of the taxa were recorded from epiphytic habitats.

Glossolomawiehleri (Gesneriaceae), a new species from the northwestern Andes of Ecuador.

A new species of Glossoloma is described from the western Andean slopes of the Pichincha Province in northern Ecuador. Glossolomawiehleri J.L.Clark & Tobar is differentiated from all other congeners by an epiphytic habit, elongate scandent shoots that exceed four meters in length, and coriaceous leaves with a velutinous indument on the lower leaf surface. The new species is illustrated, featured with field images from recent expeditions, and assigned the category of Endangered (EN) according to IUCN Criteria.

Putting vascular epiphytes on the traits map

Abstract Plant functional traits impact the fitness and environmental niche of plants. Major plant functional types have been characterized by their trait spectrum, and the environmental and phylogenetic imprints on traits have advanced several ecological fields. Yet, very few trait data on epiphytes, which represent almost 10% of vascular plants, are available. We collated 76,561 trait observations for 2,882 species of vascular epiphytes and compared these to non‐epiphytic herbs and trees to test hypotheses related to how the epiphytic habit affects traits, and if epiphytes occupy a distinct region in the global trait space. We also compared variation in traits among major groups of epiphytes, and investigated the coordination of traits in epiphytes, ground‐rooted herbs and trees. Epiphytes differ from ground‐rooted plants mainly in traits related to water relations. Unexpectedly, we did not find lower leaf nutrient concentrations, except for nitrogen. Mean photosynthetic rates are much lower than in ground‐rooted plants and lower than expected from the nitrogen concentrations. Trait syndromes clearly distinguish epiphytes from trees and from most non‐epiphytic herbs. Among the three largest epiphytic taxa, orchids differ from bromeliads and ferns mainly by having smaller and more numerous stomata, while ferns differ from bromeliads by having thinner leaves, higher nutrient concentrations, and lower water content and water use efficiency. Trait networks differ among epiphytes, herbs and trees. While all have central nodes represented by SLA and mass‐based photosynthesis, in epiphytes, traits related to plant water relations have stronger connections, and nutrients other than potassium have weaker connections to the remainder of the trait network. Whereas stem‐specific density reflects mechanical support related to plant size in herbs and trees, in epiphytes it mostly reflects water storage and scales with leaf water content. Synthesis. Our findings advance our understanding of epiphyte ecology, but we note that currently mainly leaf traits are available. Important gaps are root, shoot and whole plant, demographic and gas exchange traits. We suggest how future research might use available data and fill data gaps.

Phylogeography and Diversity Among Populations of the Toxigenic Benthic Dinoflagellate Prorocentrum From Coastal Reef Systems in Mexico

The marine dinoflagellate genus Prorocentrum Ehrenberg comprises many species occupying primarily benthic or epiphytic habitats, particularly in tropical and sub-tropical waters. Despite concerted efforts to establish phylogenetic associations, there remain unresolved issues in defining morphospecies and membership in species complexes. The study described herein addressed the inter- and infraspecific relationships of members of the Prorocentrum lima and Prorocentrum hoffmannianum species complexes (PLSC and PHSC, respectively) by applying multivariate approaches in morphotaxonomy, molecular phylogenetics and chemodiversity to establish affinities among multiple clonal isolates. Morphotaxonomic analysis showed consistency with classical morphospecies descriptors, and high variability in cell size and dimensions, but did not challenge current species complex concepts. Phylogenetic analysis of ITS/5.8S rDNA sequences from isolates from the Gulf of California, Caribbean Sea, and Gulf of Mexico coasts compared with archived global GenBank sequences served to define five consistent clades with separation of the PLSC and PHSC. Secondary structure modeling of ITS2 rRNA variation based on compensatory base changes (CBC) was effective in resolving details of the respective species complexes and even indicated putative incipient or cryptic speciation due to potential hybridization barriers. This study represents the largest (n = 67 isolates) chemodiversity analysis of polyketide-derived toxins associated with diarrheic shellfish poisoning (DSP) from a benthic dinoflagellate genus. Relative composition of some analogs (OA, OA-D8, DTX1, DTX1a, and DTX1a-D8), including two new undescribed isomers, distinguished P. lima from P. hoffmannianum sensu lato, but without clear associations with substrate type or geographical origin. Although all P. lima and most (one exception) P. hoffmannianum were toxigenic, the total cell toxin content could not be linked at the species level. This research demonstrates that clonal chemodiversity in toxin composition cannot yet be effectively applied to define ecological niches or species interactions within local assemblages. Phylogenetic analysis of the ITS/5.8 rDNA, particularly when combined with secondary structure modeling, rather than only a comparison of LSU rDNA sequences, is a more powerful approach to identify cryptic speciation and to resolve species complexes within benthic dinoflagellate groups.

A review of Australian tree fern ecology in forest communities

AbstractAustralian forest ecosystems cover almost 16% of Australia’s landmass. As the seventh‐largest forested area worldwide, these forest ecosystems have largely evolved in the face of a changing climate and fire regime, drought and human land use practice. Australian tree ferns contribute to both the unique biodiversity of these forests and current forest product markets. We review the Australian tree fern literature including: the importance of tree ferns for other components of biodiversity; their response to disturbance such as fire and silviculture; and the management of tree ferns as a product for the horticultural market. Most studies focused on tree fern response to wildfire and clearfell burn and sow logging following management and horticultural industry changes. Survival and recruitment of tree ferns after a single fire/logging disturbance event found short‐lived negative impacts. Studies of tree ferns over time include research on growth, with non‐linear growth models found to best describe tree fern age; Cyathea australis grows 2.2 ‐ 4.0 times faster than Dicksonia antarctica on average. Tree ferns perform a keystone function through habitat for epiphytes at the local scale, but it is unknown if this has an impact on biodiversity at the landscape scale. Our review found few studies on survival and recruitment following drought; multiple disturbance events such as repeated logging; and silvicultural techniques other than clearfell burn and sow. No studies had investigated the response of tree ferns to changing climate, invasive species, changes in fire frequency or effect of megafire. We conclude with recommendations for key areas of research including, future impacts due to changing climate, synecology, influence on forests, the impact of silvicultural techniques and the influence of megafires on survival.

New circumscriptions add two northern Andean species to Kohleria (Gesneriaceae).

Recent studies of type specimens and exploratory research expeditions in the northern Andes have resulted in an updated circumscription and recognition for two species of Kohleria (Gesneriaceae) in Ecuador and Colombia. A change in the rank from a variety to species is recognized for Kohleria anisophylla (Fritsch) Wiehler. The combination Kohleria andina (Fritsch) J.L. Clark & Jost, comb. nov. is provided here and a lectotype is designated. The updated circumscriptions of these two species are supported by morphology and geographic distribution. The presence of an epiphytic habit for Kohleria is discussed. Field images based on recent expeditions are provided to support the circumscriptions presented here.

Spatial relationships between spiders and their host vascular epiphytes within shade trees in a Mexican coffee plantation

AbstractWithin tree canopies, vascular epiphytes create habitats for other taxa, and their heterogeneous spatial distribution could affect the distribution of organisms associated with them, such as spiders. This study was performed in shade trees of a rustic coffee plantation located within a Tropical Cloud Forest region of Mexico. We used a spatially explicit approach to examine (1) if the richness and abundance of epiphyte‐dwelling spiders have a positive association with epiphyte abundance within trees and (2) if spiders (richness and abundance) show the same patterns of spatial distribution as the epiphytic habitat. We found that spiders were distributed on gradients of the same type as their host epiphytes. These gradients were a decrease from the center toward the edges of the tree and a decrease from the base of the trunk toward the canopy. Spiders also had aggregation patches with similar dimensions to those exhibited by their host epiphytes. Those spiders' patches were fully explained when their epiphytic habitat was also aggregated within trees. Spatial models suggested that epiphytes and spiders were also spatially structured at scales larger than a tree and smaller than an epiphyte mat. Our findings demonstrate that the spatial distribution of epiphyte‐dwelling spider communities, may partly be explained by the distribution patterns of their host plants. However, other environmental and biotic factors, not associated with epiphyte communities, are likely to be responsible for the remaining spatial patterns of spider distribution.Abstract in Spanish is available with online material.

Bromeliad habitat regulates the richness of associated terrestrial and aquatic fauna

AbstractBromeliads harbour a great diversity of fauna species. The epiphytic habit of bromeliads is subject to higher temperatures and higher incidence of light than is the epigeic habit, so we expected individuals of the Vriesea neoglutinosa species to differ in terms of the composition, richness and abundance of their fauna associated with different bromeliad habits. We carried out a study in a restinga area on Marambaia Island, Brazil. We collected 32 bromeliads, of which 16 were epigeic and 16 were epiphytic, and found a total of 1125 individual animals of 88 morphospecies. Arthropods stood out in the sample, among which 68.2% were insects. Aquatic fauna was richer in epigeic bromeliads, and terrestrial fauna was richer in epiphytic bromeliads. As expected, species composition was different for aquatic and terrestrial fauna. The heterogeneity of the restinga environment and differences in the development stages of the fauna may be factors that influence its composition. Both bromeliad habits sustain fauna with several trophic guilds that compose a complex food web and depend on the bromeliad environment. As different habits lead to different fauna types, both epigeic and epiphytic bromeliads play a role in the maintenance of local biodiversity and are important for macrofauna conservation in restingas.

Facing the communication between soybean plants and microorganisms (Bradyrhizobium and Delftia) by quantitative shotgun proteomics

The effect of plant-produced flavonoids in rhizobial cells is well-known, and flavonoids are considered the first signals in the rhizobia-plant communication. We previously reported that Delftia strains increase the performance (nodulation and nitrogen fixation) of leguminous plants in co-inoculation experiments, as compared with the single rhizobial inoculation. By using an approach based on quantitative shotgun proteomics, we explored the response of Delftia sp. JD2 cells to the presence of the flavonoid genistein (nod gene-inducer of Bradyrhizobium cells). We found that genistein up-regulates the production of regulatory proteins associated with the epiphytic habit (TetR and diguanylate cyclase), proteins involved in the formation of flagella, iron acquisition, resistance to several drugs, the rhizoplane colonization (biofilm establishment), and the rearrangement of the peptidoglycan structure and membrane proteins. These results indicate that genistein induces chemotaxis, mobility and prepares JD2 strain for an epiphytic lifestyle. We also analyzed the effect of the co-inoculation on the proteome of symbiosome-enriched fractions from soybean nodules. The fractions from co-inoculated plants showed an up-regulation of proteins involved in stress endurance (“stem 31 kDa glycoprotein”, “Kunitz trypsin protease inhibitor”, proteasome subunits) and ferritin (involved in iron storage and homeostasis), suggesting that co-inoculation with JD2 prepares the soybean plants to deal with unfriendly environmental conditions. In summary, the plant-secreted genistein functions as a chemical signal in the communications between soybean plants and Delftia sp. JD2, while the presence of JD2 would prepare the plant to cope with abiotic stresses in co-inoculation experiments.

Functional Traits of a Rainforest Vascular Epiphyte Community: Trait Covariation and Indications for Host Specificity

Trait matching between interacting species may foster diversity. Thus, high epiphyte diversity in tropical forests may be partly due to the high diversity of trees and some degree of host specificity. However, possible trait matching between epiphyte and host is basically unexplored. Since the epiphytic habitat poses particular challenges to plants, their trait correlations should differ from terrestrial plants, but to what extent is unclear as epiphytes are underrepresented or missing in the large trait databases. We quantified 28 traits of 99 species of vascular epiphytes in a lowland forest in Panama that were related to plant size, leaf, stem, and root morphology; photosynthetic mode; and nutrient concentrations. We analyzed trait covariation, community weighted means, and functional diversity for assemblages on stems and in crowns of four tree species. We found intriguing differences between epiphytes and terrestrial plants regarding trait covariation in trait relations between plant maximal height, stem specific density, specific root length, and root tissue den-sity, i.e., stem and root economic spectra. Regarding host specificity, we found strong evidence for environmental filtering of epiphyte traits, but only in tree crowns. On stems, community weighted means differed in only one case, whereas > 2/3 of all traits differed in tree crowns. Although we were only partly able to interpret these differences in the light of tree trait differences, these findings mark an important step towards a functional understanding of epiphyte host specificity.