Division Anthocerotophyta - hornworts Chloroplasts occur singly in cells and contain pyrenoids. Sporangium is long and hornlike. This is a very small group of only about five genera. Gametophyte begins as a algae-like, filamentous protonema. Leafy buds growing from the protonema become the familiar moss plants.
Sporophytes are more obvious than in liverworts, due to their usually elongate setae.
The sporophyte is covered by an operculum, which detaches at maturity. In most species, spores are dispersed by the action of a ring of teeth at the mouth of the capsule, the peristome. The vascular plants contain specialized tissues for water and food transport - xylem and phloem. All vascular plants exhibit heteromorphic alternation of generations, but the unlike the bryophytes, the sporophyte is the dominant generation. Vascular plants arose about 400 million years ago.