A stereotypical flower consists of four kinds of structures attached to the tip of a short stalk. Each of these kinds of parts is arranged in a whorl on the receptacle. A whorl is an arrangement of sepals, petals, leaves, or branches that radiate from a single point and surround or wrap around the stem. A whorl consists of at least three elements.
Most flowers have four whorls:
Mosses are bryophytes or non-vascular plants. They differ from "higher" plants by not having internal water-bearing vessels or veins, and no flowers and therefore no fruits, cones or seeds. They are small (typically 1–10 cm tall) and herbaceous and absorb water and nutrients through their leaves. Mosses have stems which may be simple or branched and upright or lax, simple leaves that often have midribs, roots (rhizoids) that anchor them to their substrate, and spore-bearing capsules on long stems. They harvest sunlight to create food through photosynthesis. Mosses do not absorb water or nutrients from their substrate through their roots, so while mosses often grow on trees, they are never parasitic on the tree.
Mosses have a gametophyte-dominant life cycle, i.e. its cells are haploid for most of its life cycle. Sporophytes (i.e. the diploid body) are short-lived and dependent on the gametophyte. This is in contrast to the pattern exhibited by most "higher" plants and by most animals.
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