平叶石灰藓是苔藓植物门的下一类植物，植株多灰绿色，密集丛生。主要分布于亚热带及热带地区。
基本介绍
- 中文学名：：平叶石灰藓
- 二名法：：Hydrogonium
- 界：：植物界
- 门：：苔藓植物门
- 纲：：藓纲
- 亚纲：：真藓亚纲
- 目：：丛藓目
- 科：：丛藓科
- 属：：石灰藓属
- 分布：：分布于亚热带及热带地区
简要介绍
石灰藓是苔藓植物门的下一类植物，植株多灰绿色，密集丛生。本属约35种，主要分布于亚热带及热带地区。中国记录有18种，为潮湿的钙质土及石灰岩上常见藓类。
主要特徵
茎直立或倾立，单一或具分枝。叶乾时多紧贴，稀捲缩；呈三角状一卵状披针形，或舌形；先端渐尖或圆钝，尖部平展或略成兜形；叶边平直，有时背卷，多全缘，稀近尖部具微齿；中肋粗壮，长达叶尖或稍突出；叶上部细胞疏鬆，多呈整齐的4-6角形，壁薄，平滑，稀具细疣；基部细胞较长大，呈整齐的长方形，平滑且透明。雌雄异株。苞叶与几同形。蒴柄细长，黄色。孢蒴直立，圆柱形；环带有分化；蒴齿左旋或直立；蒴盖具长尖直喙。常具多样的无性繁殖芽胞体。
发现研究
1975年日人K.Saito将本属归併于扭口藓属内，作为一组，即：Sect.Hydrogonium(C.Muell.）Saito但作者认为Hydrogonium之特徵显然有别于Barbula如本属叶边多平直而不明显背卷；叶基阔，叶片多呈三角状或披针状舌形；苞叶比一般叶小，且无鞘部分化；蒴齿有时直立而不旋扭；常具多样形态的无性芽胞体。见于上述明显差异，故本书同意Hilpert(1933)及P.C.Chen(1941)之意见，仍将其独立为石灰藓属。
分类
1.植物体挺硬，叶片呈披针形······································2
1.植物体较柔软；叶片多呈舌形·····································9
2.叶片先端渐尖············································3
2.叶片先端或疣或少较圆钝·······································5
3-叶片细胞全部平滑无疣·····························3.砂地石灰藓H.arcuatum
3.叶片上部细胞均具疣·········································4
4.叶片呈卵状披针形，扁平展开；叶细胞被细圆疣················2.扁叶石灰藓H.amplexifolium
4.叶片呈狭长披针形，叶先端呈龙骨状弯曲，叶细胞密被马蹄形细疣·········16.东亚石灰藓H.subcomosum
5.叶片中肋不突出叶尖·········································6
5.叶片中肋突出叶尖··········································8
6.叶细胞平滑无疣·······························18.钝叶石灰藓H.williamsii
6.叶细胞具疣状突起··········································7
7.叶中肋粗壮；叶细胞壁相当厚；叶片尖端全缘；具星芒状的无性芽胞体········7.疣叶石灰藓H.gangeticum
7.叶中肋细弱；叶细胞壁薄；叶片先端边缘有锯齿；无性芽胞体缺如·········8.细叶石灰藓H.gracilentum
8.叶片先端较阔；叶细胞较大，直径约7-8μm····················15.暗色石灰藓H.sordidum
8.叶片先端较狭；叶细胞较小，直径约5-6μm··················4.南亚石灰藓H.consanguineum
9.叶片基部特宽，成鞘状抱茎·························1.卷叶石灰藓H.amplexifolium
9.叶基不成鞘状抱茎··········································10
10.叶中肋自叶片先端突出成小尖头···································11
10.叶中肋不突出叶片先端·······································12
11叶边缘下部背卷；无性芽胞体呈纺锤形或丝状·················12.大叶石灰藓H.majusculum
11.叶边缘下部不背卷；无性芽胞缺如···················13.拟石灰藓H.pseudo-ehrenbergii
12.叶片较宽，呈卵状舌形·······································13
12.叶片较狭，呈披针状舌形······································1
13.植物体较小，高仅0．5-1cm，叶片细胞之胞壁厚·················10.爪哇石灰藓H.javanicum
13.植物体较粗大，高在2cm以上，叶片细胞壁薄·················14.四川石灰藓H.setschwanicum
14.叶片细胞壁薄而柔··········································15
14.叶片细胞壁厚···········································16
15.植物体矮小；叶细胞具明显的疣，叶上部边缘由于疣状突起而粗糙呈细齿状···17.亮叶石灰藓H.subpellucidum
15.植物体较高大（长达4-8cm）；叶细胞平滑无疣；叶边全缘无锯齿···········6．石灰藓H.ehrenbergii
16.叶片上部狭窄，先端渐尖··························11．平叶石灰藓H.laevifolium
16.叶片上部较阔，先端圆钝···……17
17.叶片具纵长皱褶；叶细胞平滑无疣或稀具细疣；无性芽胞体缺如············9.褶叶石灰藓H.inflexum
17.叶片平展无皱褶；叶细胞壁上密被小马蹄形疣；具疣细胞构成的线状无性芽胞体····5.狄氏石灰藓H.dixonianum
1.植物体较柔软；叶片多呈舌形·····································9
2.叶片先端渐尖············································3
2.叶片先端或疣或少较圆钝·······································5
3-叶片细胞全部平滑无疣·····························3.砂地石灰藓H.arcuatum
3.叶片上部细胞均具疣·········································4
4.叶片呈卵状披针形，扁平展开；叶细胞被细圆疣················2.扁叶石灰藓H.amplexifolium
4.叶片呈狭长披针形，叶先端呈龙骨状弯曲，叶细胞密被马蹄形细疣·········16.东亚石灰藓H.subcomosum
5.叶片中肋不突出叶尖·········································6
5.叶片中肋突出叶尖··········································8
6.叶细胞平滑无疣·······························18.钝叶石灰藓H.williamsii
6.叶细胞具疣状突起··········································7
7.叶中肋粗壮；叶细胞壁相当厚；叶片尖端全缘；具星芒状的无性芽胞体········7.疣叶石灰藓H.gangeticum
7.叶中肋细弱；叶细胞壁薄；叶片先端边缘有锯齿；无性芽胞体缺如·········8.细叶石灰藓H.gracilentum
8.叶片先端较阔；叶细胞较大，直径约7-8μm····················15.暗色石灰藓H.sordidum
8.叶片先端较狭；叶细胞较小，直径约5-6μm··················4.南亚石灰藓H.consanguineum
9.叶片基部特宽，成鞘状抱茎·························1.卷叶石灰藓H.amplexifolium
9.叶基不成鞘状抱茎··········································10
10.叶中肋自叶片先端突出成小尖头···································11
10.叶中肋不突出叶片先端·······································12
11叶边缘下部背卷；无性芽胞体呈纺锤形或丝状·················12.大叶石灰藓H.majusculum
11.叶边缘下部不背卷；无性芽胞缺如···················13.拟石灰藓H.pseudo-ehrenbergii
12.叶片较宽，呈卵状舌形·······································13
12.叶片较狭，呈披针状舌形······································1
13.植物体较小，高仅0．5-1cm，叶片细胞之胞壁厚·················10.爪哇石灰藓H.javanicum
13.植物体较粗大，高在2cm以上，叶片细胞壁薄·················14.四川石灰藓H.setschwanicum
14.叶片细胞壁薄而柔··········································15
14.叶片细胞壁厚···········································16
15.植物体矮小；叶细胞具明显的疣，叶上部边缘由于疣状突起而粗糙呈细齿状···17.亮叶石灰藓H.subpellucidum
15.植物体较高大（长达4-8cm）；叶细胞平滑无疣；叶边全缘无锯齿···········6．石灰藓H.ehrenbergii
16.叶片上部狭窄，先端渐尖··························11．平叶石灰藓H.laevifolium
16.叶片上部较阔，先端圆钝···……17
17.叶片具纵长皱褶；叶细胞平滑无疣或稀具细疣；无性芽胞体缺如············9.褶叶石灰藓H.inflexum
17.叶片平展无皱褶；叶细胞壁上密被小马蹄形疣；具疣细胞构成的线状无性芽胞体····5.狄氏石灰藓H.dixonianum