簡要介紹
石灰蘚是苔蘚植物門的下一類植物，植株多灰綠色，密集叢生。本屬約35種，主要分布於亞熱帶及熱帶地區。中國記錄有18種，為潮濕的鈣質土及石灰岩上常見蘚類。
主要特徵
莖直立或傾立，單一或具分枝。葉乾時多緊貼，稀捲縮；呈三角狀一卵狀披針形，或舌形；先端漸尖或圓鈍，尖部平展或略成兜形；葉邊平直，有時背卷，多全緣，稀近尖部具微齒；中肋粗壯，長達葉尖或稍突出；葉上部細胞疏鬆，多呈整齊的4-6角形，壁薄，平滑，稀具細疣；基部細胞較長大，呈整齊的長方形，平滑且透明。雌雄異株。苞葉與幾同形。蒴柄細長，黃色。孢蒴直立，圓柱形；環帶有分化；蒴齒左旋或直立；蒴蓋具長尖直喙。常具多樣的無性繁殖芽胞體。發現研究
1975年日人K.Saito將本屬歸併於扭口蘚屬內，作為一組，即：Sect.Hydrogonium(C.Muell.）Saito但作者認為Hydrogonium之特徵顯然有別於Barbula如本屬葉邊多平直而不明顯背卷；葉基闊，葉片多呈三角狀或披針狀舌形；苞葉比一般葉小，且無鞘部分化；蒴齒有時直立而不旋扭；常具多樣形態的無性芽胞體。見於上述明顯差異，故本書同意Hilpert(1933)及P.C.Chen(1941)之意見，仍將其獨立為石灰蘚屬。分類
1.植物體挺硬，葉片呈披針形······································21.植物體較柔軟；葉片多呈舌形·····································9
2.葉片先端漸尖············································3
2.葉片先端或疣或少較圓鈍·······································5
3-葉片細胞全部平滑無疣·····························3.砂地石灰蘚H.arcuatum
3.葉片上部細胞均具疣·········································4
4.葉片呈卵狀披針形，扁平展開；葉細胞被細圓疣················2.扁葉石灰蘚H.amplexifolium
4.葉片呈狹長披針形，葉先端呈龍骨狀彎曲，葉細胞密被馬蹄形細疣·········16.東亞石灰蘚H.subcomosum
5.葉片中肋不突出葉尖·········································6
5.葉片中肋突出葉尖··········································8
6.葉細胞平滑無疣·······························18.鈍葉石灰蘚H.williamsii
6.葉細胞具疣狀突起··········································7
7.葉中肋粗壯；葉細胞壁相當厚；葉片尖端全緣；具星芒狀的無性芽胞體········7.疣葉石灰蘚H.gangeticum
7.葉中肋細弱；葉細胞壁薄；葉片先端邊緣有鋸齒；無性芽胞體缺如·········8.細葉石灰蘚H.gracilentum
8.葉片先端較闊；葉細胞較大，直徑約7-8μm····················15.暗色石灰蘚H.sordidum
8.葉片先端較狹；葉細胞較小，直徑約5-6μm··················4.南亞石灰蘚H.consanguineum
9.葉片基部特寬，成鞘狀抱莖·························1.卷葉石灰蘚H.amplexifolium
9.葉基不成鞘狀抱莖··········································10
10.葉中肋自葉片先端突出成小尖頭···································11
10.葉中肋不突出葉片先端·······································12
11葉邊緣下部背卷；無性芽胞體呈紡錘形或絲狀·················12.大葉石灰蘚H.majusculum
11.葉邊緣下部不背卷；無性芽胞缺如···················13.擬石灰蘚H.pseudo-ehrenbergii
12.葉片較寬，呈卵狀舌形·······································13
12.葉片較狹，呈披針狀舌形······································1
13.植物體較小，高僅0．5-1cm，葉片細胞之胞壁厚·················10.爪哇石灰蘚H.javanicum
13.植物體較粗大，高在2cm以上，葉片細胞壁薄·················14.四川石灰蘚H.setschwanicum
14.葉片細胞壁薄而柔··········································15
14.葉片細胞壁厚···········································16
15.植物體矮小；葉細胞具明顯的疣，葉上部邊緣由於疣狀突起而粗糙呈細齒狀···17.亮葉石灰蘚H.subpellucidum
15.植物體較高大（長達4-8cm）；葉細胞平滑無疣；葉邊全緣無鋸齒···········6．石灰蘚H.ehrenbergii
16.葉片上部狹窄，先端漸尖··························11．平葉石灰蘚H.laevifolium
16.葉片上部較闊，先端圓鈍···……17
17.葉片具縱長皺褶；葉細胞平滑無疣或稀具細疣；無性芽胞體缺如············9.褶葉石灰蘚H.inflexum
17.葉片平展無皺褶；葉細胞壁上密被小馬蹄形疣；具疣細胞構成的線狀無性芽胞體····5.狄氏石灰蘚H.dixonianum
