The study of ferns and other pteridophytes is called pteridology. Members of "Physoderma" are obligate parasites of pteridophytes and angiosperms. The meristem architectures differ between angiosperms, gymnosperms and pteridophytes. It is also found in conifers and pteridophytes. In addition, it houses about 1,700 pteridophytes and 5,000 lichens. He specialized in pteridophytes, mycology, bryophytes and spermatophytes. His areas of interest encompassed Pteridophytes, Bryophytes and Spermatophytes. Conifers and pteridophytes were the most common plants. The herbarium specializes in the Pteridophytes of China, especially those of southwestern China. The plant species include bryophytes, Pteridophytes, Herbs, Shrubs, Climbers and Trees. PPG I, was produced in 2016, covering only extant (living) pteridophytes. Additionally 37 species of Pteridophytes are also found in the National Park. In 2016, the group published a classification for extant pteridophytes, termed "PPG I". Pteridophytes, like fern, on the other hand, do not possess a multicellular apical meristem. Of the pteridophytes, ferns account for nearly 90% of the extant diversity.