Captive Drops

Day 11: Moss and other bryophytes are non-vascular plants. What does that mean, exactly? Unlike vascular plants which have a structure of xylem vessels to assist in the internal transport of water, mosses are comprised of specialized but simpler tissues which absorb water by osmosis. It therefore behooves the plant to husband available moisture whenever possible. Mosses can survive prolonged dry spells because of their ability to utilize even minimal amounts of atmospheric moisture. Mosses do not have true roots. They attach to their substrate by means of fine rhizines similar to those found in some lichens. These rhizines do not absorb moisture or transport nutrients as true roots do; they simply anchor the moss to a surface. While most species reproduce by solely by sporulation (the production of spores), others are known to clone themselves by means of asexual reproduction. Although primitive in nature, mosses have derived a solid survival strategy which has allowed them to be present on the Earth for at least 300 million years in forms similar to those we see today.