![]() Although the sporophyte of many mosses is green and photosynthetic early in its development, most of the photosynthetic surface is in the stalk. For the gametophyte this is true throughout its existence. Sphagnum is a photosynthetic autotroph, it makes food (carbohydrate) through the process of photosynthesis and then uses this carbohydrate both as a material to make biomoleules and also to provide energy for metabolic activities. Recent research supports this latter view. There are two theories of spore discharge, one based on pressurization of the spore capsule as it matures and changes shape, the second argues that drying of the capsule generates tensions that eventually lead to rupture of the capsule. The structure labelled ‘d’ is the operculum cap that ‘blows’ off as spores are dispersed. Sphagnum sporophyte development-A: three archgonia at the tip of a gametophyte stem, B: sporophyte structure, C: sporophyte located at the tip of a gametophyte stalk, labelled (qs). Sphagnum exhibits the typical alternation of generations found in mosses, with a haploid gamete producing plant (gametophyte) that is relatively large, long-lived and noticeable, and a much smaller, shorter-lived diploid sporophyte that is produced on the gametophyte, produces spores, and then is shed. However, in Sphagnum the sporophyte is solely the capsule and the stalk that it sits on is haploid and part of the gametophyte. Polytrichium) the sporophytes (the diploid part) have two components: a stalk and a capsule situated at the top of the stalk. The sporophyte is less commonly seen and includes a roughly spherical capsule that opens explosively to release spores. ![]() The ability of sphagnum to hold so much water is related both to the large quantity of non-living cells that can absorb water and also to the fact that the mat of plants itself can hold water in between individual plants. The leaves of sphagnum consist of strands of narrow living cells with abundant chloroplasts, surrounding bands of much larger cells that quickly die after being produced. Plants are erect and have a cluster of branches near the top that give it a characteristic look. Individual plants may be quite long, over 30 cm, but this is including the slowly decomposing basal parts, with the green portion typically 10 cm or less. The gametophyte (haploid form) generally occurs in dense mats.
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