A STUDY OF THE CAUSES THREATENING PELLACALYX YUNNANENSIS,A SPECIES RECEIVING PRIORITY PROTECTION IN CHINA Effects of human trampling on sand-beach grass communities of the middle Yellow Sea Population genetics and breeding system of Tupistra pingbianensis (Liliaceae), a naturally rare plant endemic to SW China THE ORNAMENTAL VALUE AND APPLICATION OF RARE PLANTS IN HUNAN OF CHINA THE CHROMOSOME OBSERVATION ON 5 SPECIES OF RARE PLANTS OF CHINA Studies on Character of Seed Germination of Rare Plant Dipteronia dyeriana Paraisometrum W.T.Wang, a newly recorded genus of Gesneriaceae from Guangxi, China