A Coconut Grove in the Philippine Islands. The people of tropical regions have more uses for this plant than there are days of the year. Its fruits will float in the sea for months without injury and it is thought to have been distributed all over the tropical world by ocean currents. Its true wild home is not certainly known, but is probably tropical America. See chapter V for an account of the tree. (Courtesy of Brooklyn Botanic Garden.)
dressings were made, and the collection of sphagnum from the bogs in which it nearly always grows was the task of many who could render no other service.
The reproduction of sphagnum is not unlike that of ferns already described. There is the same necessity of a film of water in which the free swimming male can fertilize the female. But some other things about their reproduction of young differ from ferns.
In the first place sphagnum is a nonvascular cryptogam, in that its leaves have no veins or ducts in them and its minute stem is also without those conducting passages that characterize all ferns, and the flowering plants, which are considered the most highly developed of all plant life. (See Chapter I for a discussion of this point, in the section devoted to “Flowerless Plants.”)
In this moss, also, there are small branches, some of which bear only the tiny leaves, but some bear leaves and the reproductive organs. The female or archegonia are much like those in the ferns, and the antheridia or male are also, as in the ferns, minute globular organs in which are the male cells. The branches bearing males are greenish, yellow, or even reddish, quite unlike the ashy gray foliage leaves which give to sphagnum its characteristic ashy gray color. Unlike the ferns, the male cells of sphagnum have only two tails, but they nevertheless swim, tail first, to the female, when the time for fertilization comes. The female branches are found mostly toward the upper end of the plant and bear the archegonia at their extremities.
From what we know of the reproductive stages in the ferns it is now obvious enough that in sphagnum moss, as we ordinarily see it, we have, because it bears antheridia and archegonia, a quite different condition from the ordinary spore-bearing leaves of ferns. For as yet spores have not been developed on the moss. The mating of male and female cells, directly on the plant, proves that in this “plant,” at least, our ordinary notion of this moss is mostly confined to a stage in its life history comparable in ferns to the production of archegonia and antheridia on the fern prothallus. From this mating of the male and female cells there results, as in the ferns, the production of a spore-bearing structure. This consists of a spore case, matured for the most part in the chamber occupied by the fertilized female cell, but ultimately its cap is carried upward. Later on the spore case ruptures, releasing the spores. As in the ferns, these germinate, forming a short green protonema followed by a prothallus. From this a short leafy branch develops, which completes the life cycle, as this is the young moss plant.
In other words, sphagnum, as we ordinarily see it, produces, on the plant, male and female cells which unite to form a spore case with spores in it. These are shed, develop into a protonema which is followed by the prothallus and from this the young moss plant develops. In ferns the conspicuous well-known stage is the spore-bearing one, in sphagnum it is the production of male and female cells directly on what appears to be the mature plant.