둥근대이끼(P. platyphyllum)는 산주목이끼과 산주목이끼 속에 속하는 선류 식물이다. 중국, 일본, 유럽, 북한에 분포하고 있다. 특히, 북한 지역에는 관모봉, 금강산, 묘향산, 차일봉에 분포하는 것으로 알려져 있었으나, 남한 지역에는 2017년 전라북도 완주군 운주면 산북리 대둔산 수락계곡에 자생하고 있음이 처음 확인되었다. 식물체의 색깔은 녹색에서 암녹색이고 윤기가 난다. 줄기에는 중심속이 발달해 있다. 가지는 불규칙하고, 가지잎은 편평하게 붙는다. 잎은 난상 피침형으로 2.0∼2.5 × 1.0∼1.4 ㎜이며, 비대칭하는 것이 특징이다. 잎 중앙세포는 80∼127 × 10∼16 ㎛로서 형태는 장사방형이다. 본 연구에서 둥근대이끼의 형태학적 기재와 동정을 위한 주요 형태 형질의 사진, 도해 및 검색표를 제시하였다.

Fruit-discharge type of forty species of Asian Geranium were examined and their evolutionary trends and taxonomic system were discussed. Two main types of seed discharge in Geranium are made the basis of its divison into subgenera: Geranium subgenus Geranium, with a ballistic expulsion of the seed from mericarp, Geranium subgenus Robertium, with forcible discharge of the mericarp with the seed in it, seperately from the awn. Variants of the seed ejecting type permit the division of Geranium subgenus Geranium into three sections. Section Geranium, these has bristles at the base of the mericarp for prevent the seed from dropping from the divergent mericarp. Section Dissect, these has prongs at the base of the mericarp for prevent the seed from dropping from the divergent mericarp. Section Tuberosa, these has no bristles and prongs at the base of the mericarp, instead, retained of seed in pre-explosive interval by twist. Geranium subgenus Robertium was divided into two sections, Section Ruberta, with deeply wrinkled on the surface of mericarp at the time of discharge. Section Batrachioides, and section Trilopha, without wrinkle on the surface of mericarp at the time of discharge. According to the seed discharge, subgenus Geranium is thought to be more advanced than subgenus Robertium.

Vegetative characters (e.g. habitat, root, ramification and habit of stem, phyllotaxy, leaf sape, shape of leaf margin, shape of division and lobe of division, number of division, thick and texture of leaf and shape of stipule) on 35 species of Asian Geranium were reviewed to discussion propriety of taxonomic character and evolutionary trends. Wilfordii group is characterized by three divided leaf, Farreri group was grown a high altitude, and Maculatum group is grouped by life cycle of anneal. Arrangement state of leaf is alternate type G, tripartitum, G. eriostemon, and G. erianthum is thought the more primitive than the other taxon, and regarded as more advanced group the sibiricum group and pseudosibiricum group which divided of leaf deeply. Shape of leaf, division degree of lobes, shape of leaf margin and number of division are considered a good identification characters because width of change are fixed between population.