H. triquetrus is a very large, bushy moss that forms shoots from 5 to 15 or even 20 cm long, with irregularly branched, red stems. Whether wet or dry, the leaves stick out in all directions (unlike Rhytidiadelphus loreus). The leaves, which can be up to 6 mm long, are straight and have a pale, chaffy appearance, giving the shoot a unique, rather untidy character. The leaf has a double nerve, which extends about halfway up the blade and the margins are lightly toothed. Capsules are rare to occasional.

H. triquetrus grows on calcareous ground in woodland, and also on acidic ground in woods of native pine (Pinus). It can also be found in open grassland on chalk, on sand dunes and in churchyards.

Widespread and fairly frequent in Britain.

Only occasional records from Leicestershire and Rutland.