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Colorful tufts of bracts, which attract insect pollinators, terminate the vertical inflorescences of several plant species. These flag-like bracts contrast in color with the leaves below them, and are oriented perpendicular to the flowers on the inflorescence. We studied how color contrast and perpendicular orientation affect the feeding choices of bumblebees in laboratory experiments. We trained bees to feeders with perpendicular two-color displays, and subsequently recorded their choices among feeders that displayed only one of these cues. The bees preferred perpendicular displays that resembled the training model in the color of the horizontal component. We then evaluated the effects of the horizontal vs. vertical display component on foraging choices. After training bees to two-color, perpendicular displays, we allowed them to choose between displays with either the same horizontal or the same vertical component as the training model. Foragers mostly oriented to the horizontal displays to which they had been trained. We conclude that (a) bumblebees learn perpendicular, two-color displays; (b) horizontal display components influence foraging choices more than vertical components; (c) vertical visual cues might guide the approach to a feeder, serving as landmarks. We discuss possible implications of our findings for the role of extra-floral bracts in pollination. [ABSTRACT FROM AUTHOR]

Loss and fragmentation of foraging habitats, and extreme seasonality in the flowering phenology of wild plants, limit honeybee populations in Israel. This problem can be alleviated by the planting of bee forage plants in forests, parks, and along roadsides. To provide recommendations for such planting, we combined a literature survey and qualitative evaluations of experts to compile a list of 266 local wild plant species that have high food potential for bees. We also quantitatively evaluated the food potential of 32 species of trees and shrubs planted by Keren Kayemeth LeIsrael—Jewish National Fund (KKL—JNF). We recorded the following parameters of each species: main flowering season; flower morphology; type of food reward; number of flowers per plant; nectar standing crop; hourly nectar production rate; type of insect visitors; and frequency of insect visits. We ranked the surveyed species according to their potential importance as food plants, assigning high ranks to species that (a) bloom between July and February (the period of dearth in flowering natural vegetation), (b) produce large amounts of nectar, and (c) are highly attractive to honeybees. Of the species surveyed, Amygdalus communis, Eucalyptus camaldulensis, Ceratonia siliqua, and Ziziphus spina-christi best combined these benefits. A regression model indicated that high nectar production rates increased insect visitation rates, while long flowers reduced them, in an inter-specific analysis. Our study highlights the importance of diversified forestry planting to address agricultural, conservation, and recreational needs. [ABSTRACT FROM AUTHOR]

Four populations of an annual Lathyrus species new to Israel have been found since 1999. Three of these are located in the Coastal Plain, the fourth in the Judean Mountains. All grow in more-or-less disturbed habitats. These populations were identified by us as Lathyrus clymenum and compared with related or similar species to verify the identification. L. clymenum is a minor crop, grown mainly in some central Mediterranean and south European countries, but it was used for food, and traded as such, already over 3,750 years ago. Archaeobotanical findings of its seeds were discovered in the northern coast of Israel (Middle Bronze Age IIA). These findings were compared with recent material. The possibilities of its re-appearance in Israel, as escaped plants or colonizers/invaders, are discussed. [ABSTRACT FROM AUTHOR]

With the current loss of biodiversity, efforts are being amassed to prioritize biodiversity hotspots that should receive high conservation priority. These studies often compare different biogeogrpahical regions using absolute estimates of species richness or rarity. Consequently, arid, semiarid, and other areas (e.g., boreal) are often ignored or are undervalued. Here, using a regional case study, we propose and demonstrate an approach that enables us to determine plant-based hotspots over landscape units across biogeographical regions using normalized, and comparing with absolute, measures. Three botanical variables were calculated for 521 predetermined landscape units in Israel. These included plant species richness, the sum of scores of red (endangered) species, and a spatial exclusiveness score, all calculated from the Israel Plant Information Center (Rotem) database. We classified the landscape units into six rainfall belts (from extreme-arid to mesic-Mediterranean), as a normalization method to enable comparison and ranking across different environments. Residuals from the species-area curves were calculated within each belt for each of the variables, as a means to normalize for sampling effects. The 25 highest-ranking landscape units were identified as botanic hotspots, both before and after normalization. Prior to normalization, most of the hotspots were located in the Mediterranean region. Following normalization, hotspots were identified across the entire climatic gradient and corresponded with threatened habitats where many threatened plant species exist, such as wetlands, sandy loamy soil, and heavy clayey soil areas. The use of rainfall belts enabled us to identify additional important conservation hotspots that are located in relatively poor species environments, such as deserts. This method should be further applied on a global basis to identify hotspots within additional biomes that have been mostly excluded from existing global hotspot maps, such as the Taiga, Boreal forests, Tundra, and the arid and semiarid desert and Xeric shrublands. [ABSTRACT FROM AUTHOR]

Bracts are nonfloral showy structures associated with inflorescences. They are generally thought to enhance plant reproductive success by attracting pollinating insects. We investigated whether flag-like bracts at the top of inflorescences are reliable signals of floral food reward for pollinators in Salvia viridis L. Field and greenhouse data indicate incomplete synchrony between the development of flowers and bracts. Various measures of bract size, however, positively correlate with the number of open flowers on the inflorescence, and with their nectar rewards. Experimental removal of bracts from inflorescences significantly reduced honeybee visitation in the field. We compare these findings with field data on Lavandula stoechas L., another labiate species with flag-like displays. The number of open flowers in L. stoechas cannot be reliably predicted from the presence or size of the bracts. Bract clipping does not significantly reduce honeybee visits in this species. We suggest that bees learn to orient to bracts if they reliably signal food rewards and to disregard bracts if they provide unreliable signals. Asynchronous development of bracts and floral rewards can reduce the reliability of the signals and may explain the rarity of flaglike displays in pollination systems. We discuss additional selective forces that may favor bract displays. [ABSTRACT FROM AUTHOR]

Several species concepts (SC) have been suggested as ways to view species, most of them based on Mayr's Biological SC. Recent research has raised the debate on the application of the species concepts to Oncocyclus irises. All the Oncocyclus species are able to produce vital progenies when crossed, thus, according to the Biological SC, they are a single biological species. Quantitative morphological characters are continuous among populations and also correlate with environmental conditions, preventing species delimitation according to Phenetic and Ecological SC. Genetic studies revealed high genetic diversity within the populations, thus, obscure delimitation by Phylogenetic SC. Pollination of the Oncocyclus irises is not species-specific, yet no transitional forms exist on the rare occasions of sympatric/parapatric distribution, roughly supporting delimitation according to the Recognition SC. The conclusion is that Oncocyclus populations do not clearly fit into species boundaries according to the relevant species concepts. Oncocyclus irises are distributed along an Ecogeographical Speciation Cline that could lead to one of three patterns of divergence, that is, discrete, ecotonal, or continuous, along the spatial dimension. Nonetheless, the exact variation pattern is not clear because of the patchy distribution. The taxonomic status of the Oncocyclus irises is viewed in light of the evolutionary processes in this highly variable group. [ABSTRACT FROM AUTHOR]

Colchicum stevenii, an autumnal geophyte in Israel, was found to be andromonecious. Examination of the phenomenon in relation to the corm size, flowering rank, flower size, and habitat indicated that hermaphrodite flowers are larger and have a greater dry weight than male flowers. Within each individual, hemaphrodite flowers always appear at the beginning of the flowering sequence, whereas male flowers appear at the end. Smaller corms produce fewer and smaller flowers, but with a high percentage of male flowers. Populations in dry habitats have smaller corms and relatively more male flowers, and fewer and smaller flowers per individual plant, in comparison with populations of more humid habitats. The adaptive value of "sequential andromonecy" is discussed. The results are in accord with the hypothesis that under stressful conditions the individual plant allocates more reserve to male flowers. [ABSTRACT FROM AUTHOR]

Iris bismarckiana (Iris section Oncocyclus) was found for the first time in the west Gilead in Jordan. This discovery was utilized to shed some light on the taxonomic relationships among the light-colored irises in the Levant. Morphometric quantitative analysis of the Jordanian population compared to I. bismarckiana allies in Israel (I. bismarckiana in the Galilee and I. hermona in the Golan) suggests that the Jordanian population is I. bismarckiana, despite the large distance from the main distribution area. Cluster analysis, based on the morphology, revealed that some of the populations of I. bismarckiana have closer affinities to I. hermona than to each other. Populations of I. hermona and I. bismarckiana in Jordan and Israel do not differ statistically from each other in morphological traits, and should not be treated as two independent species. [ABSTRACT FROM AUTHOR]