The indigenous moss flora of New Zealand comprises almost 450 species and over 60 named varieties belonging to 57 families and representing 167 genera of which the following six are endemic, namely, Bellia, Bryodixonia, Cladomnion, Cryptopodium, Dichelodontium, and Tetraphidopsis. One-third of the species is restricted to New Zealand, while 24 are cosmopolitan. A large number are shared with Australia, Tasmania, and South America.
One-third of the mosses extends over the full length of the Dominion. Eight species are restricted to North Auckland, 35 are not found north of Banks Peninsula, and 20 others reach their southern limit in the northern portion of the South Island. Epiphytic mosses approximately equal those found on rocks or on earth. In the South Island, 54 species are restricted to the western side and 54 to the eastern side of the 50-in. isohyet.
Mosses are often confused with lichens, with hepatics, and even with tiny flowering plants. If a plant produces flowers or fruits, it cannot be a moss, and if it possesses true leaves it cannot be a lichen. Hepatics are less easily distinguished from mosses, but their leaves are commonly asymmetrical and much indented or lie in two overlapping rows, whereas in mosses the leaves are quite or nearly symmetrical and, apart from marginal serrations in some instances, are not indented. The setae bearing the spore capsules are translucent in most leafy hepatics, while in mosses they are green or coloured.
The leafy moss plant is termed a gametophyte and bears the minute sex organs – male antheridia and female archegonia. Fertilisation results in the production of a leafless sporophyte, which remains attached to the leafy plant and produces the spores which in turn initiate a new generation of gametophytes. This alternation of generations is characteristic both of mosses and of hepatics. A moss bearing spore capsules is not strictly one plant, but parent and child, the latter a permanent parasite on its parent.
Moisture and nourishment are absorbed mainly by the leaves, the rhizoids serving mainly to anchor the plant to its substratum. Mosses are classified into three main groups, termed Andreaeales or lantern mosses, Sphagnales or bog mosses, and Bryales, to which belong all the other species. Eight species of Andreaea and four of Sphagnum are recognised in New Zealand. These latter, however, display a great diversity of form.
In the Bryales the most advanced forms are Dawsonia superba and 15 representatives of the order Polytrichales. Specimens of Dawsonia, our largest and most robust moss, may on occasion attain a height of 30 in. though normally they rarely exceed a foot. Each plant has a central, erect, woody stem, surrounded by narrow linear leaves, except at the base, and in “fruiting” plants a stout terminal capsule with a peristome resembling a plug of cotton wool. Unlike those of most other mosses, the stem possesses a specialised water-conducting axis. It forms small colonies on the floor of humid forests.
Next in size is the subalpine moss Dendroligotrichum dendroides – which commonly carpets the floor of beech forests in the wetter areas. This has a long wiry stem terminated by leafy branches bearing either male or female organs, but not both. Sporophytes are uncommon in the North Island, but abundant in the South Island. A notable feature of this, and indeed of all the members of the genus Polytrichum and its allies, is the presence on the lower surface of each leaf of numerous parallel, longitudinal lamellae.
Of the mosses that produce terminal sporophytes the genera best represented in New Zealand are Bryum (21 species), Fissidens (15), Tortula (13), Macromitrium (11), and Dicranoloma and Funaria (10); while of genera with lateral sporophytes, Brachythecium and Sematophyllum each have eight species, and Camptochaete has seven. Pendulous epiphytic mosses belong to two related genera – Weymouthia, with two pale yellowish-green species, and Papillaria, with five species usually tinted reddish-brown or gold. In open and sub-alpine forests Weymouthia often assumes physiognomic importance, as do the various species of Dicranoloma on the forest floor, especially in montane beech forests. D. billardieri and D. plurisetum often form a continuous and somewhat treacherous carpet for extensive areas at a stretch, while in the wettest forests they sometimes build sub-globular mounds 1–3 ft in diameter, as also do two species of the hepatic genus Plagiochila.
In sub-alpine regions the dominant mosses belong to the four moss families – Andreaeaceae, Grimmiaceae, Dicranaceae, and Polytrichaceae; while swamps, bogs, and marshes are typically the home of the Sphagnaceae, Bartramiaceae, Dicranaceae, Bryaceae, and Amblystegiaceae. Several mosses are sub-aquatic, such as Blindia immersa or Fissidens muelleri, and three are regularly found on rocks in the bed of forest streams – Thamnium pandum, Fissidens rigidulus, and Cryphaea tasmanica, though at least a dozen can withstand periodic immersion.
Several anomalous mosses occur. These include Buxbaumia aphylla and B. novae-zealandiae; the former is unknown elsewhere in the Southern Hemisphere though wide-ranging north of the Equator, and the latter is endemic. These are primitive mosses, apparently leafless, the only visible moss being an erect sporophyte protruding from the soil or bark,½ in. tall and bearing at the tip a more or less pointed, inclined capsule of unusual shape. More anomalous still is a minute moss with the ponderous name Ephemeropsis trentepohlioides, which grows on the terminal twigs of Coprosmas and other shrubs in humid areas. In this leafless moss the minute capsules and setae arise directly from a brown felt of protonemal threads which function as leaves. This species is also found in Tasmania.
Several mosses often lie unattached to the surface soil in forested areas, notably Echinodium hispidum and Camptochaete ramulosa. Here they multiply and spread, but do not produce sporophytes. The moss Dicranoloma menziesii occasionally forms globular or lenticular moss balls, also lying unattached to the earth, but more normally all three grow as epiphytes on forest trees.
In four related genera the various species spread their leafy branches in a plane parallel to the earth and at right angles to the incident light at the apex of an upright stem. Popularly known as umbrella mosses, they include several most attractive species, such as Mniodendron comosum, often golden brown with furry stems, or Hypnodendron marginatum, when a dozen or more sporophytes arise from the central area, each with a bright red seta. A few mosses commonly invade our lawns (for example, Thuidium furfurosum and Bryum truncorum).
Except in the number of species, the moss flora of New Zealand is not surpassed by that of any other land and, with the ferns, hepatics, and lichens, constitutes the principal ornament of our native forests.
by William Martin, B.SC., Lichenologist and School Teacher (retired), Dunedin.
A Handbook of New Zealand Mosses, Sainsbury, G. O. K. (1935); Flora of New Zealand, Martin, W. (1961); Bryologist, Vol. 61 (1958), “Moss Distribution in New Zealand”, Martin, W., Tuatara, Vol. 2 (1949), “Some Notes on Mosses with Key to Commoner New Zealand Genera”, Allison, K. W.