The genus Tanacetum is one of the most important medicinal plants that contains 26 species in Iran, 12 of them are endemic. This paper reports the essential oil composition of  Tanacetum angulatum Willd. Tanacetum canacens DC. and Tanacetum pinnatum Boiss. growing wild in Iran. Plant flowers and leaves were collected from different locations of North- West of Iran. Samples were hydro-distilled ...

The genesis of phyllotaxis, which often is associated with the Fibonacci series of numbers, is an old unsolved puzzle in plant morphogenesis. Here, we show that disruption of an Arabidopsis topoisomerase (topo) I gene named TOP1alpha affects phyllotaxis and plant architecture. The divergence angles and internode lengths between two successive flowers were more random in the top1alpha mutant tha...

We recently introduced a model that predicts the degree to which a plant's lifetime seed production may be constrained by unpredictable shortfalls of pollen receipt ("pollen limitation"). Burd's comment in this issue criticized our analysis, first by arguing that the empirical literature documents much higher levels of pollen limitation than our model predicts and then suggesting that the appar...

BACKGROUND AND AIMS Allocation of resources to floral traits often declines distally within inflorescences in flowering plants. Architecture and resource competition have been proposed as underlying mechanisms. The aim of the present study is to assess the relative importance of resource competition and architectural effects in pollen and ovule production on racemes of Hosta ventricosa, an apom...

Pollination by insects is essential to many ecosystems. Previously, we have shown that floral scent is important to mediate pollen transfer between plants (Kessler et al., 2015). Yet, the mechanisms by which pollinators evaluate volatiles of single flowers remained unclear. Here, Nicotiana attenuata plants, in which floral volatiles have been genetically silenced and its hawkmoth pollinator, Ma...

Flowering is controlled by a variety of interrelated mechanisms. In many plants, the environment controls the production of a floral stimulus, which moves from the leaves to the shoot apex. Apices can become committed to the continuous production of flowers after the receipt of sufficient amounts of floral stimulus. However, in some plants, the commitment to continued flower production is evide...

In hermaphroditic plants, female reproductive success often varies among different positions within an inflorescence. However, few studies have evaluated the relative importance of underlying causes such as pollen limitation, resource limitation or architectural effect, and few have compared male allocation. During a 2-year investigation, we found that female reproductive success of an acropeta...

To study genetic effects of habitat fragmentation on plant performance and plant response to biotic interactions, we performed a greenhouse study with plants from 27 populations of the common plant Lychnis flos-cuculi differing in size, isolation, and microsatellite heterozygosity. We germinated seeds of 449 plants and grew up to nine offspring per maternal plant in single pots assigned to a fa...

Pathogens that rely upon multiple hosts to complete their life cycles often modify behavior and development of these hosts to coerce them into improving pathogen fitness. However, few studies describe mechanisms underlying host coercion. In this study, we elucidate the mechanism by which an insect-transmitted pathogen of plants alters floral development to convert flowers into vegetative tissue...

In Primula vulgaris outcrossing is promoted through reciprocal herkogamy with insect-mediated cross-pollination between pin and thrum form flowers. Development of heteromorphic flowers is coordinated by genes at the S locus. To underpin construction of a genetic map facilitating isolation of these S locus genes, we have characterised Oakleaf, a novel S locus-linked mutant phenotype. We combine ...