Analyses of Anatomic Structure and Their Systematic Significances of Zingiberaceous Roots of 28 Species in China

The comparative anatomy of roots in 14 genera and 28 species of Zingiberaceae in China was studied.The results show that:(1) the transverse section of zingiberaceous root can be divided into epidermis,cortex and stele from outside to inside.(2)Epidermis:It is one layer of cells slightly lignified and mostly with hairs in all examined species.(3)Cortex:The cortex is composed of parenchyma cells presenting 15～16 layers or more than 45 layers,and can divided into exodermis,middle cortex and endodermis according to the characteristics and location.Exodermis present as 1～9 layers of compact,suberized,but always thin-walled cells immediately below epidermis.Middle cortex generally consists of large parenchyma cells,the cells is irregular and contains a few starch grains;or consists of large and middle parenchyma cells,the outline of these cells which usually contain a lot of starch grains and prism present round,oblong or irregular,or consists of small parenchyma cells where starch grain is absent and the outline of these cells generally present as round,ellipse,square and oblong,the wall of parenchyma cells usually developed into reticulate thickening.The oil-cells can be found in all genera examined.Endodermis contains one layer of cells whose wall usually developing U-shaped thickening.(4)Stele:Including a thin-walled,1-layered pericycle,a polyarch arrangement of vascular tissues and parenchymatous medulla commonly occupying central stele.However,the differences of the medulla usually present in different genera.(5)The conclusion that ginger family was divided into two subfamilies and four tribes based on the molecular evidence was hold.However,the viewpoint that the subfamilies contain genera and tribes,respectively,especially,that ginger subfamily contained Globbeae,Hedychieae,and Zingibereae of the old systematics was hold incompletely or not hold.As for the tribe level,the characters of the roots in zingiber have more consistent,and the genus circumscription was clear as well as,so the independent tribe on zingiber was hold in this paper.