▁leaf ▁tip ▁is ▁ac ute , ▁leaf ▁marg ins ▁are ▁plane , ▁slightly ▁d entic ulate ▁towards ▁tip , ▁mid - leaf ▁cells ▁are ▁large , ▁costa ▁or ▁the ▁central ▁st ork ▁of ▁the ▁leaf ▁extends ▁nearly ▁to ▁leaf ▁tip . ▁The ▁growth ▁form ▁is ▁proc umb ent ▁but ▁small , ▁young ▁plants ▁can ▁attach ▁themselves ▁closely ▁to ▁rocks ▁and ▁appear ▁fl atten ed . ▁ ▁Ident ification ▁Pl aty h yp n id ium ▁rip ari odes ▁di agnostic ▁features ▁include ▁its ▁compar atively ▁large ▁size , ▁up ▁to ▁ 1 5   cm ▁long , ▁large ▁leaf ▁size ▁up ▁to ▁ 8   mm ▁with ▁el ong ated ▁mid - leaf ▁cells . ▁C aps ules ▁are ▁abund ant ▁and ▁frequently ▁produced ▁and ▁feature ▁long ▁cur ving ▁lid . ▁In ▁the ▁UK , ▁m oss es ▁that ▁grow ▁in ▁similar ▁habit ats ▁and ▁may ▁be ▁confused ▁with ▁P . ▁rip ari odes ▁include ▁the ▁aqu atic ▁genus ▁Bra chy the ci um ▁and ▁Le pt od ict y um ▁rip arium . ▁All ▁these ▁m oss es ▁are ▁pl aty car pus , ▁have ▁a ▁single ▁n erve ▁per ▁leaf ▁and ▁overlap ▁in ▁size ▁but ▁can ▁be ▁separate ▁by ▁leaf ▁shape , ▁cell ▁structure ▁and ▁growth ▁form . ▁ ▁Distribution ▁W ide ▁global ▁distribution ▁found ▁South ▁of ▁the ▁Ar ctic ▁polar ▁region ▁in ▁flow ing ▁fresh water ▁mainly ▁in ▁Northern ▁Hem is phere . ▁Found ▁commonly ▁in ▁the ▁British ▁Is les . ▁ ▁References ▁ ▁Category : H yp n ales