Sphagnum cristatum

Sphagnum Moss

Sphagnum cristatum Hampe

Sphagnum cristatum is the most common species of Sphagnum in Australia and is the only moss to be used in commercial industry. The Class Spagnopsida formerly contained a single order, the Sphagnales, with one monogeneric family, the Sphagnaceae to which S. cristatum belongs. However, the taxonomy is under current investigation with the recent discovery of a new species, which possesses significant anomalies relative to the concept of the genus, and as a consequence, has been segregated into a separate order, family and genus.

Sphagnum peatlands make up only a small percentage of the Australian landscape and are a unique and distinct environment. They are restricted to the sub alpine zones of south-eastern New South Wales, Victoria and Australian Capital Territory and are currently listed as a threatened community.

S. cristatum is a small to robust plant, pale to brownish-green in colour and forms dense mats of intertwined lateral branches with mop-like heads. It produces distinct reddish-brown spherical capsules which are borne on a thickened pseudopodium, but are rarely seen in natural populations, suggesting that reproduction is chiefly by vegetative means. Spore dispersal occurs in the spring when the capsules are mature. The leaves of S. cristatum are spirally arranged and are constructed of an inner core of dead hyaline cells surrounded by a narrow wall of living photosynthetic cell. The hyaline cells are large and contain small perforations that allow the plant to absorb and retain almost 20 times its own weight in water.

Sphagnum moss is used extensively in the horticultural industry because of its super-absorbent qualities. It is most often used in the propagation of orchids, as a soil additive to promote water retention and for the long-distant transportation of rootstock. It has also been used as a surgical dressing since World War 1 because of its antibacterial qualities and its capacity to absorb 6 times the amount of fluid as cotton.

S. cristatum is not easily cultivated because it requires a very narrow set of conditions under which it can grow successfully. It needs a stable temperature of 23-25 degrees, regular watering from a spray system for 20 seconds every 20 minutes and a limited light intensity, so is best suited to glasshouse conditions. Sphagnum doesn't respond well to the chlorine content in tap water and should only be watered with filtered water. Soil is not required for the cultivation of Sphagnum - it can be spread thinly into plastic seed trays. Small amounts of liquid fertiliser can be applied to encourage growth but care must be taken with the application. Pest control is not needed because Sphagnum has devised its own natural defense system against insect and fungus attack by liberating hydrogen ions and creating an intolerable pH level in its immediate environment.

Limitations exist in the cultivation of S. cristatum mainly because it is very slow growing and requires glasshouse conditions. The annual growth rate of natural S. cristatum populations is estimated to be between 0.4-4.2 cm. For these reasons some gardeners who like to see instant results may be disappointed. S. cristatum is a beautiful and fascinating plant and is well worth the little extra patience it requires to grow.

Text by Sharon Brown (2002 Student Botanical Intern)

References

Whinam, J. 1997. The sustainability of Sphagnum moss harvresting in Australia. Parks and Wildlife Services. Tasmania, Australia.

Richardson, D.H.S. 1981. The Biology of Mosses. Blackwell Scientific Publications, London, UK.

Seppelt, R.D. 2000. The Sphagnopsida (Sphagnaceae; Ambuchananiaceae) in Australia. Hikobia Vol. 13: pp 163-183.

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