Fontinalis

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Fontinalis is a widespread genus in the northern hemisphere, occurring in both lakes and running water. The Giant Water Moss holds the record for being the largest of the mosses, sometimes extending two meters from its rocky substrate and, in some instances, entirely covering a stream bed. Because it forms such extensive mats, it is an important habitat for stream invertebrates and even a protective site for fish eggs. Its large size provides cover not only for the tiny Chironomids that nestle in the leaf bases, but also for occasional large insects like Pteronarcys. Hydropsychids and Rhyacophila are common Trichoptera, with Ephemerella being the most common of Ephemeroptera. Nemourids and Leuctra are the most common of the Plecoptera, and where the water is sufficiently fast, Simulids are common at the surface. Besides insect larvae, the leaves are the home for a variety of epiphytic diatoms(algae).

In general, species in this genus occur in sparkling, clean water, but in some parts of the world the same species can live in concrete ditches receiving rice paddy effluent or on rocky substrata of enriched streams. It generally occurs in acidic water (pH 4-5.5), but European and Japanese populations seem able to occupy circum-neutral waters as well. High temperatures and bright light seem to be its worst enemies. Most of the taxa examined grow best at 15 degrees C, whereas Fontinalis neo-mexicana seems to have 10 degrees C as an optimum. After about 5 weeks at 20 degrees C all the species studied turn brown and cease growing. This is usually not sufficient to kill them; they will resume growth when cooler temperatures return.

In at least several species, sexually derived capsules can mature in mid-winter (February in New Hampshire), thus being missed by most observers, and spring runoff completely erodes the capsules, leaving nothing. Capsules have been reported infrequently, partly because male and female reproductive organs are on separate plants, and getting the tiny sperm safely to a female is an improbable feat in running water. Fontinalis spreads mostly by stolons and fragments. Most of the species seem to produce their sexual reproductive organs in late summer/early autumn in response to short days and possibly cool temperatures. Fontinalis antipyretica is an exception to that, producing them in spring.

Rhizoids are important in anchoring the species to the substrate, usually to rocks or submerged roots and logs, but occasionally the plants are able to grow from buried stolons in sand, as does the Fontinalis neomexicana in Yellowstone. The rhizoids respond to contact with a substrate by producing multiple short branches and a cementing substance. The rhizoids are positively gravitropic and the plants are negatively gravitropic.

Fontinalis is particularly sensitive to copper, exhibiting chlorosis of its tips overnight in water drawn from copper pipes. At 3 ppm, the copper is generally toxic, causing loss of chloroplasts, high concentrations of phaeophytin a, and a chlorotic appearance of the tips of branches. At 10 ppm, irreversible plasmolysis occurs and the cells are colorless. It is relatively insensitive to cadmium, exhibiting no detrimental effects until levels are way beyond those tolerated by invertebrates and fish. Like most mosses, it is a good heavy metal accumulator and may be useful in metal clean up in some situations. One of its advantages is that it does not release its heavy metals when it dies because they are mostly bound to cell walls and other structures that do not disintegrate easily upon death.

Fontinalis antipyretica has two varieties and may be distinguished from other Fontinalis species in the eastern U.S. by having strongly keeled leaves. The variety gigantea has large leaves of about 5-8 mm wide that form protected chambers where Chironomids and young insects hide. The variety gigantea tends to grow in quiet water of pools, probably because its large, folded leaves are very susceptible to damage in fast water, but the typical variety can occur in relatively fast water. Fontinalis novae-angliae occurs in both fast mountain streams and in lakes. Its leaves have a few tiny teeth at the tips and the leaves are slightly rolled. Its most distinctive feature in the field is that its branches seem to come off at definite angles (30-45 degrees) with respect to the stem, pointing toward the tip. It produces numerous rhizoids on short stolons that have reduced leaves, permitting a good hold to the substrate and a means for spreading. Fontinalis dalecarlica is a species of rapid water and has a very strong, nearly black stem, permitting it to survive considerable abrasion. The easiest way to recognize it is that when you grab it under water, it feels like you have encountered a wire brush. Its older (lower) leaves are typically eroded away in fast water. It holds to its substrate by strongly bound rhizoids, but it generally does not have the short, specialized stolons of Fontinalis novae-angliae. Fontinalis flaccida occurs much less frequently than the previous three, so I hesitate to generalize on its habitat. I have found it in pools and in lakes. Its name comes from the very flexible (flaccid) stems, which tend to limit it to quieter water. It somewhat resembles a Fontinalis dalecarlica, but its stems are quite different. Fontinalis hypnoides occurs much more commonly in the midwest and can be distinguished from the previous three by small, flat leaves about 3 mm wide and reddish stems. In Upper Michigan streams it usually gets abraded away in summer and must resume growth from a stubble of stems in late fall and winter. Fontinalis duriaei (or F. hypnoides var. duriaei) is much larger than F. hypnoides. Its leaves are usually flat, but can be somewhat concave or even slightly keeled, varying on the same plant. Its stems are less reddish and its leaves are about the same size as those of F. dalecarlica and F. novae-angliae. It is the fastest growing species, by far, of the ones described here, but the warm summer water, often coupled with exposure above water, result in its abrasion as well, so fall and winter are a period of regrowth that continues through June. Fontinalis neomexicana is a western species known in the east only from Michigan. Its leaves are keeled like those of Fontinalis antipyretica, but they are closely arranged so that no space is between them and the branches (including leaves) tend to taper at both ends. Other species occur in the east, especially farther south, but are uncommon in the northeast.

The Fontinalis species cannot be very clearly defined without illustrations, for which one should refer to:

Welch, W. 1960. Monograph of the Fontinalaceae. Martinus

Nijhoff, The Hague, Netherlands. 357 Pp.

Crum, H. A. and Anderson, L. E. 1981. Mosses of Eastern North

America. Columbia Univ. Press, New York, 2 Vol.