Isoetes baodongii (Isoetaceae), a New Basic Diploid Quillwort from China

Isoetes baodongii Y. F. Gu, Y. H. Yan & Yi J. Lu (Isoetaceae) is here described as a newly discovered, rare and endangered species of quillwort from eastern China. It has a basic diploid chromosome count of 2n = 22. Isoetes baodongii is similar to I. sinensis T. C. Palmer in its overall appearance and was previously misidentified as such. It differs from I. sinensis in its chromosome number and in megaspore ornamentation. In I. baodongii, both the proximal surface and distal surface of the megaspore are echinato-cristate, whereas in I. sinensis the proximal surface is echinate and the distal surface echinato-cristate. Microspores of I. baodongii have echinate ornamentation.