Morphologic evaluation of some Northern Khorasan rangeland species seeds from the point of view of seed dispersal

Seed dispersal distances of mother plant is a basic aspect in plant life history, and have great effects on plant ecology, evolution and conservation. Seed dispersal modes of species can often be recognized by morphological characteristics of fruits and seeds. A laboratory experiment was conducted on seeds of 24 Northern Khorasan rangeland species during 2008. The size of seeds was measured by digital caliper with a precision of. 0.01 mm (operating instruction in resolution 0.01 mm), and the seed's shape were observed by binocular and drown by hand in scale of 30-80 times. Seeds were categorized in five categories based on their shapes and morphological traits namely, Nutrient Containing Structure (i.e. Artemisia seiber), Balloon Structure (i.e. Agropyron trichophorum), Elongated Appendages (ie. Salsola arbusculaformis), No Appendages (i.e. Stachys inflate and Iris songarica) and other Specializations (i.e. Kochia prostrate). According to the results, balloon structure category was identified as the most common seed dispersal mode in the zone of Northern Khorasan (with 9 species) which let the wind disperses the seeds easily. The elongated appendages category was placed in the next group and other categories owned third place. It can be concluded that balloon structure has provided the most suitable dispersal system for the seeds studied in Northern Khorasan rangeland.