In this article we will discuss about the morphology of sphagnum with the help of a suitable diagram.
Sphagnum is a cosmopolitan genus that grows abundantly as dense masses in ponds, lakes or sites where due to seepage soft water is’ available but there is little lime. It reaches its greatest abundance in cooler temperate regions of northern hemisphere where it dominates the vegetation of wetlands. The plant is perennial, the stem continues to grow year after year.
Around the plants the water is so acidic that there is but little decay of dead basal portions. The older parts die and the dead organic remains of these plants along with remains of the other plants form a compact mass, known as peat. Accordingly, it is known as peatmoss. Since it is typical of bogs, it is also described as bog-moss. As a peat-former, it is commercially the most valuable of bryophytes.
In India, Sphagnum is represented by about 20 species in Himalayas, east as well as west. S. ceylonicum has also been reported from south India. However, in India the growth of this moss is not so luxuriant that could result into a full peat or a bog.
The plants are branched leafy gametophytes (Fig. 4.5A, B), differentiated into stem and leaves. The leaves are spirally arranged and widely spaced, with little or no chlorophyll. There are no rhizoids. On the stem, at a position where the fourth leaf is expected to arise, there is a fascicle of 3-8 lateral branches (Fig. 4.5C), which are also spirally arranged.
Each fascicle has two or more divergent branches and two or more slender pendent branches, which drop downwards along the stem.
The stem is only a few inches in length with close aggregation of short and stumpy branches towards the apex (Fig. 4.5A) make it look like a head or capitulum. The branches also have spirally arranged leaves. With the growth of axis in length the branches towards the apex elongate and the main stem in turn forms a few short branches.
Occasionally, one of the branches becomes robust and grows upwards, like the main axis, producing a tuft of branches and apical cluster of branches. This dominant branch is known as innovation. The plant is capable of effective vegetative propagation; the branches on separation form new individuals.