为丛鲜科中最大之一属，最常见之属。本属全世界已报道约350种，主要分布于南北半球的温带地区及暖热地区，多生于钙质土或石灰岩上。我国已记录有20种，广布于我国南北各地的平野及高山。

命名 学名 Barbula

科名 丛藓科 Pottiaceae

属名 扭口藓属 Barbula

中文名 扭口藓属

描述 属17扭口藓属Barbula Hedw．

Spec. Musc. 115. 1801．

模式种：扭口藓B. unguiculata Hedw.形态结构 植株矮小，纤细或略粗壮，绿色或带红棕色，往往密集丛生，或呈紧密的垫状。茎直立，具分化的中轴，叉状分枝，基部密生假根。叶干时紧贴，湿时散列，有时背仰，呈卵形，卵状披针形，或三角状—线状披针形，先端渐尖或急尖；叶边全缘，整齐背卷；中肋粗壮，长达叶尖或在叶尖稍下处消失，稀突出叶尖；叶上部细胞形小，呈多角状圆形或方形，壁稍增厚，不透明，具单疣或多个细疣，稀具乳头或平滑；基部细胞稍长大，多呈短矩形，平滑无疣。雌雄异株，雌苞叶与叶同形，稀较大而具高鞘部。孢蒴直立，稀稍倾立，呈卵状圆柱形，稀稍弯曲；环带多分化；蒴齿细长，齿片呈线形，多呈螺形左旋，稀直立，密被细疣；蒴盖圆锥形，先端具短味；蒴帽兜形。孢子小，多呈黄绿色，稀红棕色，多平滑，稀具细疣。有时叶腋或叶面上着生无性繁殖的芽胞体。

本属实为丛鲜科中最大之一属，最常见之属，早年该属曾包括甚多的丛藓科植物属及种，如现今存在的纽藓属(Tortella )，流苏鲜属(Crossidium），墙藓属(Tortula )，芦荟藓属(Aloi na )等等，均先后从其独立出成属。但V. F. Brotherus（1924）在《植物科属自然系统》中所列扭口藓属下，仍包括许多不同类型的藓类。 Loeske (1910) JR Herzog（1926)均对本属的成分作过讨论，认为其所包含的种类不纯。Hilpert (1933)将其原被列为亚属的一部份独立成属，如Asteri scium属、石灰藓属仔如drogonium )及扭毛藓属(Strehlotrich um ).同时将原Didymodon属中的亚属Frythrophyllum独立成属，即是目前本书所列的红叶藓属(Bryoerythrophyllum )，而将Didymodon属中的其余种类归并入扭口藓属，陈邦杰(1941)，以及陈邦杰与黎兴江(1963，1985)均同意Hilpert (1933)及K. Walther (1983)的意见，将Didymodon属归并于本属。而K. Saito (1975)仍将Didy-modon单独列为一属，并主要以腋生假根及叶基细胞的形态及颜色，以及叶细胞的形态构造作为与扭口藓属分属的依据，作者认为这类特征并不稳定，实不足以据此来分属，故仍将Didymodon属之大部种当归隶于Barbulla属，而前者之一些种名在本书中均作为本属有关种类的异名处理。

分种检索表 1.叶细胞壁平滑或具单疣；中肋细弱，长不及顶，均在叶尖以下消失·····················，···················

2.叶细胞壁均具多个或单个细疣，稀平滑；中肋粗壮，长达叶尖或稍突出·······································4

3.叶片呈三角状狭披针形；中肋在叶中上部即渐消失；叶细胞平滑无疣；孢蒴呈卵形·······················13.剑叶扭口藓B. rufidula

4.叶片呈卵状阔披针形．中肋至叶尖消失；叶细胞具单疣；孢蒴呈圆柱形·······································3

5.叶片下部宽，上段急尖，先端狭长；蒴齿细长，螺旋状向左扭曲·····························15拟溪边扭口藓B. subrivicola

6.叶片卵状披针形，先端渐尖；蒴齿较短，直立·······································12.溪边扭口藓B. rivicola

7.叶片较短宽，呈阔卵圆形，长卵圆形或舌形，先端圆钝··············································5

8叶片较狭长呈卵状、三角状或线状披针形，先端渐尖··················．····························9

9.叶细胞呈5-- 6角形，壁较薄，排列整齐，每细胞上具数个马蹄形细疣········································6

10.叶细胞呈多角状圆形．壁较厚，排列不整齐，胞壁平滑或具单一小圆疣·······································7

11.叶片呈阔卵形或狭卵形，先端圆钝，略呈兜形；植株矮小，高约1 - 2cm·····························17.云南扭口藓B. tenii

12.叶片呈长卵状舌形．先端平展，圆钝而具小尖头；植株较高大，高3- 5cm····························19.扭口藓B. unguiculata

13.植株细小，高仅0. 5cm左右；叶成覆瓦状贴生，呈阔卵形···································9.细叶扭口藓B. perobtusa

14.植株较长大，高2. 5-6cm；叶伸展不成狱瓦状，呈狭长卵形·············································8

15.植株呈鲜绿色；叶先端较宽，顶端圆钝，略呈兜形·····································18.灰土扭口藓B. tophacea

16植株呈暗红带黑褐色；叶先端较狭而渐尖，不呈兜形·····································8.黑扭口藓B. nigrescens

17.潮湿时叶片背仰；叶细胞壁不规则的强烈增厚··················································10

18.潮湿时叶片斜伸；叶细胞壁不强烈增厚······················································15

19.叶基特宽大，呈三角状心形，向上呈狭成长披针形；叶基细胞呈狭长蠕虫形，由于壁特厚，壁间穿孔处明显突出而使壁呈波状·····6.大扭口藓B. gigantean

20.叶片呈卵状披针形；叶基细胞呈短或长短形，壁平直稍增厚，无明显壁孔······································11

21.叶片先端较短宽；叶细胞壁疣具单一小圆疣，稀具2疣····································2.红扭口藓B. asperifolia

22.叶片先端较狭长；叶细胞壁具疣个小圆疣，稀仅具1-2疣··············································12

23.植株呈黄绿色，较长大，高达8cm ;叶片强烈背仰；中肋背面粗糙·······························10.反叶扭口藓B. reflexa

24.植株呈黄绿色，高约4cm以下；叶片稍背仰，中肋背面平滑·············································13

25.叶片呈三角状狭披针形；常具多细胞组成的无性芽胞····································11.硬叶扭口藓B. rigidula

26.叶片呈卵状阔披针形；不具无性芽胞······················································14

27.叶基细胞明显分化，呈狭长方形；蒴齿较短，一次左旋···································20.土生扭口藓B. vinealis

28.叶基细胞无明显分化，呈短矩形；蒴齿较长，3次以上左旋···································5.北地扭口藓B. fallax

29.叶片呈三角状、心状或线状披针形；中肋突出叶尖；叶细胞多呈方一多角形，排列整齐································16

30.叶片呈卵状披针形；中肋不突出叶尖；叶细胞呈3--5角形，排列不整齐·······································18

31.叶片柔软，呈线状狭长披针形；叶细胞平滑无疣·····································14.狭叶扭口藓B. subcontorla

32.叶片挺硬，呈三角状或心状披针形；叶细胞稀具单疣···············································17

33.叶排列紧密、贴生；叶片呈三角状披针形；中肋突出部份短，呈刺芒状···························4.长尖扭口藓B. ditrichoides

34.叶排列疏松，散生；叶片基部呈心形，向上成狭长披针形；中肋突出部份特长，呈毛状，（狭长毛尖的长度，常超过叶身长）···7.长肋扭口藓B. longicostata

35.叶片呈阔卵状或长卵状披针形·先端宽渐尖；叶平展，叶边背卷不明显····························16.短叶扭口藓B. tectorum

36.叶片呈狭卵状披针形，先端狭长呈线状；叶边明显背卷··············································19

37.叶片先端往往细长且扭曲，顶部突然膨大，且向腹面折合成鹅头颈状；叶上部细胞呈整齐的方形－多角形，平滑无疣····1.鹅头叶扭口藓B. anserin capitata

38叶片先端呈细长线形，但不扭曲，不膨大；叶片上部细胞呈3-- 5角形，胞壁不规则增厚，具1-2个细疣··············3.尖叶扭口藓B. constricta