Acrocarpous Mosses (Upright Growth)

This group gathers Mosses and Liverworts subcategory members belonging to the acrocarpous mosses, a growth form rather than a single family, defined by an upright, typically unbranched or sparsely branched stem that produces its spore-bearing capsule at the very tip of the main stem, ending that stem's further growth. It spans the haircap mosses of the family Polytrichaceae, among the largest and most structurally complex mosses, with a rigid, wiry stem and, uniquely among mosses, internal water-conducting tissue that functions much like a simplified version of the vascular tissue found in ferns and flowering plants, the widespread genus Bryum and its relatives in the family Bryaceae, and the rock mosses of the family Andreaeaceae, which split their capsule open along four longitudinal slits rather than through the lidded, hinged opening most other mosses use. Nearly every family gathered here grows as dense cushions, tufts or short turfs rather than the sprawling mats typical of the pleurocarpous mosses gathered separately, a visible consequence of the same single-tipped growth pattern that also ends each stem's ability to keep growing once it has produced a capsule.