Developmental and Structural Section
Yang, Chaodong , Zhang, Xia , Zhou, Cunyu , Seago, James L .
Root and Stem Anatomy of Four Grasses in the Yangtze River Jianghan Floodplain.
Bermudagrass (Cynodon dactylon), centipedegrass (Eremochloa ophiuroides), knotgrass (Paspalum distichum), and limpograss (Hemarthria altissima) are among the grasses which occupy the floodplain of the Jianghan Plain near the Three Gorges Dam along the Yangtze River. We have studied these four species to determine their structural and histochemical root and stem traits for understanding why they are successful in this unique old floodplain. Adventitious roots are very similar among the four with an endodermis, wall stages I-III, and a hypodermis with exodermis, also wall stages I-III. Lysigenous aerenchyma with few radiating cortical plates of living cells is characteristic; there is often a sclerenchymatous pith. In rhizomes and stolons the four species show considerable variation; three species have horizontal rhizomes under the soil and stolons along the soil surface, but centipedegrass has only stolons. In both rhizomes and stolons, under the thick-walled epidermis, most have a ring of peripheral mechanical tissue of one to three layers with suberin lamellae and lignified secondary walls; some species have embedded vascular bundles and regular chlorenchyma in stolons. In all but limpograss, the central cylinder is delimited by a sclerenchyma ring, the outer layer of which is also suberized in Bermudagrass. Vascular bundles are associated with and scattered internally to the sclerenchyma ring. Rhizomes have more extensive cortex than stolons. There are usually small pith cavities present in rhizomes and larger cavities in stolons in all but knotgrass which has expansigenous aerenchyma in cortex and pith.
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1 - Yangtze University, The School of Horticulture and Gardening, Jingzhou, Hubei, 434025, China
2 - SUNY at Oswego, Biological Sciences, Oswego, NY, 13126, USA
Presentation Type: Oral Paper:Papers for Sections
Location: 555B/Convention Center
Date: Wednesday, August 4th, 2010
Time: 8:15 AM