Structure and function of mucilaginous achenes of Artemisia monosperma inhabiting the Negev Desert of Israel

Artemisia monosperma is a sand-fixing perennial shrub occurring in the Negev Desert of Israel and is distributed in the Saharo-Arabian phytogeographic region. Its achenes form a mucilaginous layer when wetted. The surface and cross section structure of the dry achenes and the developmental stages of the mucilage when wetted were examined by SEM. In natural seed populations the achenes on the soil surface adhere to the sand particles of the sand crust, or are buried near the sand surface. Groups of dry free achenes and adhered achenes were placed on the natural sand crust during the autumn before the first rains. The length of time it took ants to collect the free and adhered achenes was noted. The results indicated that strong achene adherence to the sand crust may delay seed collection by ants.