The Anatomy Study Of Several Cycads On Nutrition Organ

The structure of roots, stems, rachises and pinnaes in several species of cycads was studied by microscopy method for anatomy research. The results indicated:These cycad species had some differences in their transverse section structure of pinnaes . Macrozamia moorei: Stomaes were confined to both upper and lower epidermis. Palisade issue that appeared in both adaxial side and abaxial side was well-developed .The vein was parallel. The arrangement of vascular bundles and mucilage canals was alternate in the same periclinal line. Zamia furfuracea: Palisade issue was underdevelopment or incomplete development. Spongy issue was net-shaped or arranged transversely with some intercellular space, where always had a large vent. The vein was parallel;Dioon holmgrenii: Palisade issue was not very well-developed. The vein was parallel vascular bundles and mucilage canals arranged in the same anticlinal line. Cycas shiwandashanica: Palisade issue was well-developed, while spongy issue arranged compactly, with some accessory transfusion tissue in both side. Midrib was raised more prominently in adaxial surface than abaxial side, and it took on semicircle-shaped .with periclinal side.The accessory transfusion tissue in midrib region was well-developed. C. multipinnata: Palisade issue was relatively well-developed and arranged regularly. Accessory transfusion tissue distributed in spongy tissue.The degree of raised midrib was slight.C. miquelii: Pinna had two layers of palisade tissue. Accessory transfusion tissue can be found in spongy tissue and midrib region was raised slightly.Among different species, the number of vascular bundles of rachiseswere difference; the pattern that vascular tissue arranged in transverse section were all with typical or non- typical near overturn Ω -shaped, but the shapes they arranged were much more different. The cycad species also had different mucilage canal number, but the pattern which they arranged were just the same; Several cycad species such as M. moorei, Z. furfuracea and D. holmgrenii had very small epidermis cells, which were nearly roundish or elliptic shape, meanwhile the other species such as Cycas shiwandashanica, C.multipinnata and C. miquelii had very large epidemis cells, which were rectangular-shaped.The stem of these species was approximate the same. Both cortex and pith of them were very large and obvious. Vascular tissue,which was very small, consisted of numerous vascular bundles arranged in ring. The vascular bundles were also very small and sperarated by well-developde medullary rays. They had secondary growth, by which they developed few vascular tissue. Xylem was relatively larger in comparison with phloem in size, but it was not very well-developed, so that the stem of them were manoxylic.Natural root (also called general root) had some characters in common in the secondary growth: secondary xylem was relatively more well-developed than phloem, but they also possessed their own speciality: the natural root of Zamia furfurcacea , the stele was solid, with homotype rays; the secondary xylem of natural root in Dioon holmgrenii, Cycas shiwandashanica and C.miquelii was divided into two parts, dissimilar type rays.The structure of coralloid root was as follows: periderm and out cortex were very thin, while inner cortex was large. The cells in the middle of cortex (alga zone) was very big, and arranged in ring, but these algal cells had different shape. The primary xylem of coralloid roots was diarch or triarch.