The diaspores of many plant species are adapted to dispersal by ants (myrmecochory). The ants carry the diaspores into their nests where the appendages of the diaspores (elaiosomes) are consumed. Little is known, however, about the fate of diaspores in the colony, i.e., whether elaiosomes are consumed only by the larvae or also by the workers. In this study, the distribution of Corydalis cava (Fumariaceae) elaiosomes was monitored between the larvae and the working caste of laboratory colonies of Myrmica rubra (Formicidae, Myrmicinae). In the first part of the study, 15 N labelled elaiosomes were found to be mainly consumed by larvae. To find out whether elaiosomes are a more attractive food source than an artificial, nutritionally optimized diet for ants (Bhatkar diet), a combined 13 C and 15 N labelling experiment was conducted. Ants were offered 15 N labelled elaiosomes for two days (pulse labelling), while being continuously fed with 13 C labelled Bhatkar diet over 19 days. Under the given laboratory conditions, elaiosomes proved to be a far more attractive diet for the larvae than Bhatkar diet, contributing 87 ± 2 % of the daily nitrogen and 79 ± 3 % of daily carbon incorporation of larvae during the first four days of the experiment. The mean elaiosome incorporation met 73 ± 5 % of nitrogen and 63 ± 6% of carbon demand of workers during the first four days of the experiment. Generally, incorporation rates in workers (per dry body mass) were lower both for carbon and nitrogen during the experiment -by a factor of 6.8 for nitrogen and by a factor of 6.2 for carbon compared to larvae. On a colony basis, workers received 39 % and larvae 61 % of the elaiosome nitrogen. The results indicate that elaiosomes are a major food source for growing larvae and thus support the hypothesis that elaiosomes play an important role in the life cycle of temperate ants.

A taxonomic study into the anatomical, morphological and phytochemical differentiation of the genus Mentha L (Lamiaceae) in Bosnia & Hercegovina and Slovakia is presented. Following a population-based approach and using hierarchical cluster analyses the following basic species and hybrids corresponding to exclusive branches, i.e. groups, in the constructed hierarchies were recognized: Mentha aquatica, M. spicata, M. arvensis, M. longifolia, M. rotundifolia, M. × piperita, M. × villosa, M. × verticillata, M. × gentillis, M. × gracilis and M. pulegium. These groups were independently found by separate analyses of the sampled anatomical and morphological variation. In contrast, these anatomically and morphologically defined species exhibited a high level of phytochemical polymorphism which was largely inconsistent with the hierarchical classification. Among the analysed characters, the inflorescence type, dentation of the leaf margin, hair density, the type of capitate glandular hairs, and the main containing compound in essential oil proved most useful for the discrimination of taxa. However, most of the observed traits were not exclusive to a particular species and only the combined consideration of traits revealed coherent taxonomic groups. Basic species and hybrids are described in detail based on the anatomical, morphological and phytochemical characters used for their definition. The performed cluster analysis finally supported hypotheses on the parentage of some of the studied hybrids.

This paper focuses on some less frequently discussed points of myrmecochory and provide an overview on: (1) the convergent origin of elaiosomes; (2) their chemistry; (3) importance of the lipid-rich elaiosomes as food source for ant populations and demography; (4) to what extent chemical signals by the plants mediate ant-dispersal; (5) the fate of the seeds and benefits for plants; and (6) the habitat preferences and phenology of temperate myrmecochorous plants.

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In the published paper [1], the following plant species are listed: Mentha longifolia var. lavanduliodora, Mentha spicata and Mentha spicata var. crispa.[...]