Seed coat morphology of the genus Juncus L.
The seed morphology of six species of the genus Juncus L. (Juncaceae), involving wild annuals and perennials was studied in Northeast of Iran using Light and Scanning Electron Microscope (SEM). Seed morphology (light microscope) of the investigated species exhibits certain variations in shape, size and surface ornamentation. Results of SEM analysis reveals that there are different patterns of seed surface. Seed shape and surface structure exhibit some diversity among taxa indicating systematic significance in species differentiation. An identification key to the investigated taxa is provided based on seed characters in this research.
he genus Juncus L. (Juncaceae) is a widely distributed rushes with nearly 220 species identified worldwide and 20 species in Iran. Rushes are found in diverse habitats and occupy areas of every continent except Antarctica. Most diversity of the genus is in mesophytic and boreal regions of the world. For the first time, this genus was described by Linnaeus in 1753. He reported 15 species of Juncus and divided them into two groups, according to stem type. After Linnaeus, several authors (e.g., Boissier (1881); Buchenau (1875, 1890, 1906)) have studied this genus based on the morphological characters and tried to provide a system to divide the genus into subgenera, sections and subsections. Revisionary studies revealed that systematic significance of seed coat morphology, rarely investigated in Juncus. Buchenau (1867) and Engelmann (1866) investigated the seed morphology of Juncus using light microscopy. These studies formed the basis of Juncus seed investigations. Brooks and Khun (1986) studied seed morphology of 15 species of four subgenera of Juncus from Kansas by using light and Scanning Electron Microscopy (SEM). Knapp and Naczi (2008) investigated taxonomy, morphology, and geographic distribution of the Juncus longii complex and studied the seeds of three species of Juncus by SEM. Results of this study revealed that the seeds of these species differ in size and shape. Abdel Khalik (2010) studied seed coat morphology and systematic significance for 10 species of Juncus from Egypt and presented a key based on the seed coat morphology for identification of the investigated taxa. In the present study we used Light and Scanning Electron Microscopy in order to compare seed morphology and seed-coat traits among species of the genus Juncus distributed in the Northeast of Iran (North, South, and Razavi Khorassan provinces). The aim is to determine if seed-coat morphology provides useful characters in interspecies differentiation.
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