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The red list has become a ubiquitous tool in the conservation of species. We analyzed contemporary trends in the threat levels of European orchids, in total 166 species characterized in 27 national red lists, in relation to their reproductive biology and growth form, distribution area, and land cover where they occur. We found that species in central Europe are more threatened than those in the northern, southern, or Atlantic parts of Europe, while species were least threatened in southern Europe. Nectarless and tuberous species are significantly more threatened than nectariferous and rhizomatous taxa. Land cover (ratios of artificial land cover, area of pastures and grasslands, forests and inland wetlands) also significantly impacted the threat level. A bigger share of artificial land cover increases threat, and a bigger share of pasture and grassland lowers it. Unexpectedly, a bigger share of inland wetland area in a country increased threat level, which we believe may be due to the threatened nature of wetlands themselves relative to other natural land cover types. Finally, species occurring in multiple countries are on average less threatened. We believe that large‐scale analysis of current IUCN national red lists as based on their specific categories and criteria may particularly inform the development of coordinated regional or larger‐scale management strategies. In this case, we advocate for a coordinated EU protection and restoration strategy particularly aimed at central European orchids and those occurring in wetland area. Species in central Europe are more threatened than those in the northern, southern or Atlantic parts of Europe, while species were least threatened in southern Europe. Land cover (ratios of artificial land cover, area of pastures and grasslands, and inland wetlands) was also shown to have a significant impact on the threat level. A bigger share of artificial land cover increases threat, and a bigger share of pastures and grasslands lowers it.

Entomophilous plants produce flowers with bright colours, patterns, and rewards like nectar, pollen, etc. for self-advertising. Many such plants only have pollen as a reward, so they deceive pollinators by appearing to offer more reward than is actually present. This is accomplished by hairy filaments, broad anther connectives, variously modified staminodes, etc. More than 20 angiosperm families have heteromorphic stamens, the significance of which has not been adequately studied. Their role with regard to Commelina diffusa , Dictyospermum montanum and Rhopalephora scaberrima of Commelinaceae is investigated here. These plants, apart from being nectarless, produce short-lived flowers and are an excellent system for studying the relevance of morphological adaptations in reproductive success. It has been suggested that the dimorphic anthers address the conflict of using pollen, the carriers of male gametes, as a reward to lure pollinators, thereby reducing the available gametes for fertilization. This is accomplished by functionally separating the anthers for ‘feeding’ and ‘pollinating’ purposes. Our study showed that while the feeding anthers infatuate the insects and are manipulated by them, the pollinating anthers succeed in maximizing pollen exports by using specific un-groomed ‘safe sites’ on the body of the insect to solve the conflict by using pollen as a reward.

The presence of nectarless flowers in nectariferous plants is a widespread phenomenon in angiosperms. However, the frequency and distribution of nectarless flowers in natural populations, and the transition from nectariferous to nectarless flowers are poorly known. Variation in nectar production may affect mutualism stability, since energetic resource availability influences pollinators' foraging behavior. Here, we described the spatial and temporal nectar production patterns of , a bee-pollinated species that naturally presents nectarless flowers. Additionally, we compared nectariferous and nectarless floral disks in order to identify histological, subcellular and chemical changes that accompanied the loss of nectar production ability. For that we used standard methods for light and transmission electron microscopy, and gas chromatography coupled to mass spectrometry for chemical analyses. We verified that 47% of flowers did not produce nectar during the whole flower lifespan (nectarless flowers). We also observed remarkable inter-plant variation, with individuals having only nectarless flowers, others only nectariferous ones and most of them showing different proportions of both flower types, with variable nectar volumes (3-21 μl). Additionally, among nectariferous flowers, we registered two distinct rhythms of nectar production. 'Early' flowers produced nectar from 0 to 24 h, and 'late' flowers produced nectar from 24 to 48 h of anthesis. Although disks from nectariferous and nectarless flowers displayed similar histological organization, they differed strongly at subcellular level. Nectariferous ('early' and 'late') flowers exhibited a cellular apparatus typical of nectar secretion, while nectarless flowers exhibited osmophoric features. We found three aliphatic and one aromatic compound(s) that were detected in both the headspace of flowers and the disks of nectarless flowers, but not the disks of nectariferous flowers Although the remarkable variation in nectar availability may discourage pollinator visits, nectarless flowers might compensate it by producing volatile compounds that can be part of floral scent, acting as chemical attractants. Thus, nectarless flowers may be helping to maintain pollination in this scenario of trophic resource supply scarcity. We suggest that can be transitioning from a nectar-based pollination system to another resource-based or even to a deceit mechanism of pollination.

PREMISE OF THE STUDY: It has been hypothesized that two flower types permit flexible allocation of resources to female and male functions, yet empirical evidence for the sex‐allocation hypothesis remains scarce in gynomonoecious species. To characterize resource allocation to pistillate and perfect flowers and allocation of perfect flowers between gynomonoecious and hermaphroditic individuals, we examined the flexibility and whether female‐biased allocation increases with plant size in the hermaphroditic‐gynomonoecious herb Eremurus anisopterus. METHODS: Frequency of gynomonoecious individuals, flower production, and plant size were investigated in different populations. Floral allocation was compared among the three flower types of E. anisopterus. KEY RESULTS: Frequency of gynomonoecious plants varied from 2–17% in nine populations. Only larger plants produced female flowers at the bottom of racemes. Both female and perfect flower production tended to increase proportionately with plant size in gynomonoecious individuals. Female flowers did not produce less biomass than perfect flowers from hermaphroditic or gynomonoecious plants. However, both female and perfect flowers from gynomonoecious individuals had lighter stamen mass, but larger pistil mass, than perfect flowers from hermaphrodites. CONCLUSIONS: Although the prediction of an increase in female flower number with plant size was not observed in E. anisopterus, the flexibility of sex allocation in gynomonoecious species was confirmed in that gynomonoecious individuals had a female‐biased floral allocation compared to hermaphroditic individuals. Such comparisons of gynomonoecious to hermaphroditic individuals permit us to unveil a sexual adjustment strategy: flexibility of sexual investments within plants.

In animal-pollinated flowers, the pollinators cannot detect the presence of nectar before entering flowers, and therefore flowers may cheat by not producing nectar. An earlier model suggested that a mixed strategy of producing nectarful and nectarless flowers would be evolutionarily stable. Here we compare nectarless flowers as a cheating strategy with three competing hypotheses namely \"visit-more-flowers\", \"cross-pollination enhancement\" and \"better contact\". We collected field data on 28 species of plants to test some of the differential predictions of the hypotheses. Nectarless flowers were detected in 24 out of 28 plant species. Correlations of percent nectarless flowers with floral and ecological variables support the cheater flower hypothesis. We further model the cost-benefits of cheating and show that an evolutionary stable ratio of nectarless to nectarful flowers can be reached. The equilibrium ratio is mainly decided by factors associated with pollinator density and pollinator learning.

Pollinators are expected to respond to low reward availability in an inflorescence by visiting fewer flowers before departure, thus potentially causing reduced visitation, but also reduced geitonogamous selfing. I tested this hypothesis using Anacamptis morio, an orchid that does not reward its pollinators. Supplementation of inflorescences with artificial nectar did not result in an increase in fruit set on supplemented inflorescences compared to control inflorescences and tended to reduce pollinia removal. Supplementation resulted in reduced fruit quality, but there was no evidence that this was as a result of inbreeding depression. Behavioral experiments showed that pollinating bumble bees, as predicted, visited more flowers on supplemented inflorescences. Bumble bees also deposited more self-pollen on supplemented inflorescences, but this was marginally significant. Bumble bee queens removed significantly more pollinia from control inflorescences, while Bombus terrestris and B. lucorum workers did not. I conclude that while pollinators behaved as predicted, there was weak evidence that pollinia removal, pollen deposition, and fruit set followed the predictions of the hypothesis. I argue that this was probably because some pollinators were more efficient at removing and depositing pollen on control inflorescences, while others were not.

Herbivory is a very common phenomenon in nature, which may considerably alter subsequent survival and reproduction of affected plants. We examined the effects of three levels of experimental defoliation (0%, 50% or 100% of the leaves removed) on reproductive behaviour, leaf production, survival and flowering of two nectarless orchids, Serapias vomeracea and Dactylorhiza sambucina. Neither orchid species showed differences between the non-defoliated and defoliated plants in total pollinia mass, but seed production was significantly lower in defoliated plants. The male reproductive traits appear to be more buffered against the effect of defoliation than female traits. Defoliation also decreased leaf area and the probability of flowering in the year following the treatments. In this paper, we show that natural levels of herbivory can severely affect both current and future reproduction in these two orchid species.

Floral deception, which mainly appears in highly evolved families such as Orchidaceae, was studied in Central Finland. In nectarless Dactylorhiza incarnata, the deceptive pollination system has been considered to function best in remote habitats such as marshes, where flowering plants attractive to pollinators are rare (remote habitats hypothesis). In contrast, the magnet-species theory predicts that a nectarless plant benefits from growing in the vicinity of nectar-containing species. These hypotheses were tested by adding attractive, nectar-containing violets (Viola x wittrockiana) to orchid populations. The percentage of fruit set in D. incarnata was adversely affected by the violets, probably because interspecific exploitation competition for pollinators took place in favour of the violas at the expense of the orchids. This result gave no support for the magnet-species theory and supported the remote habitats hypothesis.

We investigated the breeding systems of Liparis kumokiri and L. makinoana (Orchidaceae) in Korea. Liparis kumokiri is self-compatible, but L. makinoana is self-incompatible. The two Liparis species showed little fruit set in natural conditions (10.2%—12.2% for L. kumokiri and 0.1%—0.2% for L. makinoana). However, a great increase in fruit set was achieved by hand-pollinations. The much lower percentage of fruit set observed in L. makinoana may reflect combined effects of pollinator limitation and self-incompatibility.