Polytrichaceae

Polytrichaceae is a common family of mosses whose members tend to be larger than other mosses, with the larger species occurring in particularly moist habitats. The leaves have specialized sheaths at the base and a midrib bearing photosynthetic lamellae on the upper surface, and these mosses sustain high rates of photosynthesis in ample light and moisture. Unlike all other mosses, the hydroid-based vascular system of the family is continuous from stem to leaf and can extract water from the soil through transpiration. In most species the sporophytes are relatively large, the setae are rigid and the calyptrae are hairy.