Division Mosses (Bryophytes)
Mosses are the oldest and simplest-built higher plants and are thought to have come from algae. Most consist of a stem and leaves, but they have no true roots and no vascular tissue: they attach to the soil with thin threads called rhizoids and take in water over the whole body. So they stay small (4–5 mm to 40 cm) and live in damp places. In higher plants the sexual generation (gametophyte) alternates with the asexual generation (sporophyte); in mosses the green plant we see is the gametophyte, so the sexual generation dominates. At the stem tip of Funaria the antheridia make two-flagellate sperm and the flask-shaped archegonia make one egg cell each. In rain water a sperm swims to an egg and fuses with it; the zygote grows into the sporophyte — a stalk with a capsule (sporangium) on top. Ripe spores scatter; on damp soil they grow into a green thread-like growth and then, through buds, into a new leafy plant. The textbook says there are over 20 000 moss species; current counts give about 12 000 species of true mosses, and about 20 000 for all bryophytes together.
| Generation | What it is | Parts |
|---|---|---|
| Gametophyte (sexual) | the green plant | stem, leaves, rhizoids; antheridia, archegonia |
| Sporophyte (asexual) | grows from the zygote | stalk and sporangium |
Magnifier observation: take a small piece of Funaria or another moss from a ditch edge or damp wall (do not strip the whole mat); under the lens find the stem, leaves and the stalk with the capsule, and draw them. Safety: never look at the sun through the lens or focus its light on paper or skin; take care on wet slippery ground; wash hands. Dry it and glue it onto a herbarium sheet.