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Ferns and lycophytes

by  Patrick Brownsey

Dominant in native bush, and important traditionally to Māori for food and medicine, ferns have also become pervasive as a symbol of New Zealand identity. The fern motif is featured in commercial logos, creative design, and on national sports team jerseys. Ferns are a distinctive part of the country’s cultural and natural history.


Land of ferns

Ferns and lycophytes abound in New Zealand’s rainforests. In the humid interior they carpet forest floors, and climb and perch on tree trunks and branches. Tall, graceful tree ferns line the sides of streams and dominate in damp gullies. Outside the forest, ferns are also conspicuous. Many roadside banks and damp hillsides are covered in a luxurious growth of kiokio (Blechnum novae-zelandiae). Bracken (Pteridium esculentum) and ring fern (Paesia scaberula) form extensive stands in open country, and on the coast hardy ferns like shore spleenwort (Asplenium obtusatum) grow on exposed cliff faces.

Changing fronds

Thread ferns (Blechnum filiforme) begin life on the ground, where they scramble around until they find a trunk to climb. On the ground they produce only short fronds with rounded segments, but as they grow upwards their fronds become larger, with more elongated segments. Finally, well above head height, they produce fertile fronds with very slender segments. The lower fronds appear so different from the upper fronds that people mistake them for different species.

What are ferns and lycophytes?

Ferns and lycophytes are green plants that lack flowers. They reproduce by microscopic spores, rather than by seeds as in flowering plants or conifers. What distinguishes them from the other spore-producing land plants such as mosses or liverworts is that their life cycle involves two separate, independent phases: a leafy plant phase that produces spores; and an inconspicuous, short-lived plant that bears sex organs. It is the leafy, spore-producing plant most people think of as a typical fern or lycophyte.

Structure

Ferns and lycophytes typically have three main parts:

  • Stems. There are various types, including creeping or climbing ones with widely spaced fronds, short or compressed stems from which a crown of fronds arise, and the tall, upright stems of tree ferns.
  • Fronds. There is usually a stalk with a flat blade divided into segments. New fronds are tightly coiled into a spiral, popularly known as fiddleheads or koru.
  • Spore-producing structures or sporangia. Fertile fronds carry reproductive structures, sterile fronds do not.

Distinguishing ferns from lycophytes

Ferns

There is no single character that defines ferns. One large group is easily recognised by its highly divided fronds with branching veins and spore-bearing structures (sporangia) on the margins or undersides. The other group is not as leafy, and contains members that look quite different from each other. Some, such as fork ferns, whisk ferns and horsetails, were previously grouped with lycophytes and known as ‘fern allies’, but DNA evidence suggests they are actually ferns. Collectively, ferns belong to a group known as monilophytes.

Confusing common names

In the mid-18th-century the great Swedish botanist Linnaeus grouped clubmosses and spikemosses with true mosses. It took another 50 years or so before botanists realised that clubmosses and spikemosses were distinct from mosses, but by then they were stuck with common names that described them as types of moss.

Lycophytes

Lycophytes include clubmosses, spikemosses and quillworts. Their sporangia are on the upper surface of small leaves with unbranched veins. The leaves are spirally arranged around the stem. Lycophytes are of an ancient lineage, no more closely related to ferns than to seed plants, and therefore inappropriately called ‘fern allies’. They belong in their own subphylum equivalent to the rest of the vascular plants.


Reproduction

Sexual reproduction

Mature ferns produce fertile fronds with brown patches called sori on their edges or undersides. Sori are made up of clusters of spore-bearing capsules that split open, releasing large quantities of spores. If these land in a damp place they germinate, developing into tiny heart-shaped plants called prothalli. Within these plants, sexual reproduction takes place.

Fern prothalli produce male and female sex organs on their undersides. When it rains, sperm released from the male organs are carried by water towards the female organs. Fertilisation occurs when the sperm fuse with egg cells in the female organs. The fertilised eggs grow into leafy fern plants.

Lycophytes have a similar reproductive cycle.

Hybrids

Some ferns, notably spleenworts (Asplenium), hybridise. Hybrids are formed when prothalli of two different species germinate alongside one another. They must be physically close enough for sperm from one plant to join with and fertilise the egg cells of the other plant. The fertilised egg develops into a normal-looking plant, but usually produces malformed spores. More than 40 different hybrid fern combinations have been recorded in New Zealand.

Reproduction without sex

Many ferns and lycophytes also have non-sexual or vegetative means of reproduction. The most familiar is the hen and chickens fern, mouki (Asplenium bulbiferum). It produces little copies of itself (‘chickens’) on the upper surface of its fronds. These are easily detached from the parent frond (‘hen’), and take root when they fall to the ground.

Some ferns and lycophytes produce buds on their stems from which new plants grow. The tuber sword-fern (Nephrolepis cordifolia) produces starch-filled tubers along its creeping stem. When the parent fern dies, or if the tubers are detached, the tubers sprout leaves and roots and become a new plant. Crown ferns (Blechnum discolor) produce runners that take root and produce a new plant where they touch the soil. The alpine clubmoss (Huperzia australiana) sometimes has buds near the top of its shoots that sprout roots and a stem when they fall to the ground.


Ferns and lycophytes in New Zealand

Numbers of species

Although ferns and lycophytes are a conspicuous feature of New Zealand’s vegetation, the country is not as richly endowed in species as many other places. New Zealand has 194 native species and 35 that have been deliberately or accidentally introduced and have become established in the wild. This is a tiny fraction of the 12,000 known species worldwide, but is fairly typical of temperate floras. Rich fern floras are found in tropical countries. New Zealand’s tropical neighbours Fiji and New Caledonia, each with a land mass one-fourteenth the size of New Zealand’s, have 250 or more fern and lycophyte species.

Largest fern families

Many distinctive fern families are found in New Zealand. They include species that range from tiny ferns a few millimetres long to 20-metre-tall tree ferns.

Filmy ferns

With 27 species, filmy ferns (genera Hymenophyllum and Trichomanes) form the largest fern family in New Zealand. They thrive in humid forests – their translucent fronds, just one or two cells thick, lose water easily and curl up in dry conditions. Some, such as the kidney fern or raurenga (Cardiomanes reniforme), grow on the forest floor, while others are epiphytic on the trunks of trees and tree ferns. Hymenophyllum malingii is one of the most unusual in this respect, as it is usually only found growing on dead trunks of kaikawaka (Libocedrus bidwillii).

Hard ferns

Hard ferns (Blechnum) are the next largest group, with 23 species. They have two types of frond. Sterile fronds are green and leafy, while fertile fronds have very narrow segments bearing copious brown, spore-bearing capsules (sporangia). Some species develop red or pink fronds when growing in the open.

Spleenworts

New Zealand has 18 species of spleenwort (Asplenium), so named because they were thought to cure diseased spleens. They are readily recognised by the herringbone arrangement of sori on the undersides of the fronds.

Tree ferns

Tree ferns have a thickened, vertical stem topped with an umbrella-like crown of fronds. They can be found throughout the country, in the bush and along its margins, as well as standing in groves in pasture. Eight species grow in mainland New Zealand, and two (Cyathea milnei and C. kermadecensis) are only known from the Kermadec Islands, north of New Zealand.

Whekī (Dicksonia squarrosa) is probably the most common tree fern, often found in groves in damp lowland forest. It is a hardy plant and will re-sprout from underground stems after fire or bush clearance. Mamaku (Cyathea medullaris) and gully fern (C. cunninghamii) are the tallest, growing to over 20 metres. Silver fern or ponga (C. dealbata) is readily distinguished by the white underside to its frond. Soft tree fern (C. smithii) is the world’s southernmost tree fern, growing on the Auckland Islands at 50˚ south. It is recognised by its skirt of dead fronds around the trunk.


Habitat

Ferns and lycophytes are found in most land and freshwater environments in New Zealand, with the exception of the highest mountain tops.

Coast and cliff

Few ferns thrive on exposed coast or dry, inland rock faces, but those that do are equipped for survival. Coastal ferns such as Blechnum blechnoides, B. durum, shore spleenwort (Asplenium obtusatum) and Asplenium appendiculatum have fleshy or leathery fronds that withstand salt spray and protect against desiccation. Ferns growing on dry rock faces are usually covered in hairs or scales that protect against drying winds and intense sunlight.

Forest

Most of New Zealand’s ferns and lycophytes are found in the forest. Many species are confined to moist, shady, lowland forest. This is the natural environment of filmy ferns, hen and chickens fern (Asplenium bulbiferum), gully fern (Pneumatopteris pennigera) and kiwakiwa (Blechnum fluviatile).

The dampness of the soil has a bearing on which species grow. Silver tree fern (Cyathea dealbata) and crown fern (Blechnum discolor) can tolerate drier conditions and are more likely to be found on upper slopes and ridges than in damp gullies.

At higher altitudes, in wet mountain forests, large clumps of crepe ferns (Leptopteris hymenophylloides and L. superba) are a striking feature. Their thin, translucent fronds are similar to a filmy fern, but standing up to a metre tall, crepe ferns are unlikely to be mistaken for the much smaller filmy fern species.

Forest epiphytes

Epiphytes and climbing ferns are common in wet forests. Four species of fork fern (Tmesipteris) grow on the fibrous trunk of tree ferns. Strange-looking, they lack roots, and consist of a protruding stem with flattened leaves. Hanging clubmoss (Huperzia varia), hanging spleenwort (Asplenium flaccidum) and sickle spleenwort (A. polyodon) are associated with large perching lilies (Astelia and Collospermum), and are often found hanging out of clumps of these nest epiphytes.

Disturbed ground

Some ferns prefer disturbed ground. Ring fern (Paesia scaberula), water fern (Histiopteris incisa) and thousand-leaved fern (Hypolepis millefolium) quickly colonise exposed ground when canopy trees are overturned in strong winds. They die out when shaded by other species. According to fossil pollen records, bracken fern (Pteridium esculentum) increased dramatically following the arrival of humans in New Zealand. It grew quickly in areas of burnt forest, and repeated fires led to its persistence at a site, for it could re-sprout from underground stems – an ability few other New Zealand plants have.

Alpine areas

About 20 species of fern and lycophyte grow in alpine areas. Alpine shield fern (Polystichum cystostegia) grows in the shelter of large boulders or tussock grasses in summer. The fronds die back to a central tuft during winter. Two alpine clubmosses, Huperzia australiana and Lycopodium fastigiatum, are found in a variety of subalpine and alpine environments from bogs to rock fields. At very exposed sites, L. fastigiatum is usually bright orange.

Warm environments

A few tropical species, including the soft fern (Christella dentata) and swamp fern (Cyclosorus interruptus) survive in the far north, where they are safe from frosts. Also frost-free, the thermal areas of the central North Island such as Karapiti, Waimangu and Ōrākei Kōrako are home to the fork fern (Psilotum nudum) and ladder fern (Nephrolepis flexuosa), which grow on heated ground along banks or tracks.

Lakes

The pillwort (Pilularia novae-zealandiae) and quillwort (Isoetes species) grow submerged in lakes and alpine tarns. Pacific azolla (Azolla filiculoides) forms floating mats on the surface of ponds, often appearing bright reddish-purple in summer.


Distribution

Shared species

Of New Zealand’s 194 native ferns and lycophytes, 90 species (46%) are endemic and 104 species (54%) also live in other countries:

  • 95 in Australia
  • 56 in the Pacific and the Malaysia–Indonesia region
  • 15 in temperate South Africa
  • 14 in the subantarctic islands and South America.

This distribution differs from that of New Zealand’s seed plants, which have a high degree of endemism – 84% are found nowhere else. It is likely that ferns and other spore-producing plants (such as mosses and liverworts) are more widespread because the lightweight spores are easily blown long distances by strong winds.

Trans-Tasman exchange?

If New Zealand ferns and lycophytes are of recent origin, it is likely they were carried by westerly winds from Australia. However, anticyclones in the south Tasman Sea produce easterly winds from New Zealand to Australia, so it is possible that some ferns and lycophytes which evolved in New Zealand have been dispersed east to Australia.

Distribution

Most endemic ferns and lycophytes live in the south, in cool rainforest. By contrast, those species shared with Australia and tropical countries are found mainly in northern New Zealand.

How did they get to New Zealand?

Ferns and lycophytes belong to ancient groups of plants with long fossil records, extending back some 410 million years in the case of lycophytes, and 380 million years for ferns.

There are two possible ways that native ferns and lycophytes arrived in New Zealand:

  • They may have been on the New Zealand land mass when it split away from the supercontinent Gondwana about 85 million years ago.
  • Their spores may have blown to New Zealand from populations on nearby land masses, and become established.

It was once thought that because New Zealand ferns and lycophytes belong to ancient groups of plants, they had a Gondwanan origin. However, this view is now being challenged. Evidence seems to suggest that most arrived as wind-blown spores in the intervening period since New Zealand separated from the supercontinent.

Weeds and invasive species

Some 35 ferns and lycophytes introduced to New Zealand are now established in the wild. A few have become weeds and some are potentially invasive. The most threatening are:

  • African clubmoss (Selaginella kraussiana), which displaces native ferns, mosses and liverworts on stream banks in damp forest, and regenerates easily from fragments
  • common horsetail (Equisetum arvense), an extremely invasive weed of open river banks
  • male fern (Dryopteris filix-mas), an increasingly common weed in the South Island.

Ferns in New Zealand culture

Māori uses

Food and medicine

Māori ate a number of ferns. The stems of underground bracken (Pteridium esculentum) contain starch and were a staple food. However, bracken is now known to contain cancer-causing chemicals and should be avoided. More of a delicacy was king fern or para (Marattia salicina), which was cultivated for its tuberous root. The young, curled fiddleheads of many species are edible and were eaten as greens. They are being cultivated again under their Māori name of pikopiko. The inner core of mamaku or black tree fern (Cyathea medullaris) yields a slimy pith that was cut into slabs and baked in a hāngī (earth oven).

Several ferns were used for their medicinal properties, for example, as poultices for skin conditions.

Construction and weaving

Tree fern trunks were used to build houses and food stores, as they are slow to rot and last well in the ground. Today, whekī (Dicksonia squarrosa) is used for retaining walls. Stems of Lycopodium volubile and mangemange (Lygodium articulatum) were used as binding twine. Stems of the clubmoss puakarimu (Lycopodium deuterodensum) were woven with flax to make waterproof capes.

The Victorian fern craze

The fashion in Victorian England to collect, cultivate and display ferns spread to New Zealand. Two Aucklanders, Eric Craig and Thomas Cranwell, produced albums of pressed ferns for sale. Examples of these are held in New Zealand museums (and elsewhere). In 1880, fern enthusiast H. B. Dobbie used the cyanotype process – an early form of photography – to produce illustrations of 148 New Zealand ferns which he published in book form. They are now known as ‘blue books’ because the ferns appear as white silhouettes on a blue background. Few copies of Dobbie’s blue books survive. Forty years later, Dobbie wrote New Zealand ferns, the definitive reference work on New Zealand ferns for more than 60 years.

Marquetry ferns

Anton Seuffert was a Bohemian-born cabinetmaker who worked in Auckland from about 1860. He was greatly admired for his intricate inlaid marquetry designs, particularly of ferns, on writing bureaux, tables and fern-album covers. The Larkworthy table, now at the Royal Botanic Gardens in Kew, England, features 29 identifiable species of New Zealand fern.

Symbol of New Zealand

Ferns are an unofficial symbol of New Zealand’s national identity. Their dominance in native bush, and their importance as food and medicine, led to their common use as design elements in traditional Māori carving. Today, the koru is used as a commercial logo for Air New Zealand. Fernland was an early colloquial name for New Zealand, and later the fern was associated with the country’s products. One of the most enduring is Fernleaf butter.

Silver fern

Today’s New Zealand Post uses the silver fern for marketing its stamps, and it has also appeared on coins, banknotes and the nation’s coat of arms. It has inspired generations of decorative artwork. The Silver Fern was the name of the passenger railcar that ran from Auckland to Wellington between 1970 and 1991. Increasingly, there have been calls for the silver fern to replace the Union Jack on the New Zealand flag. Above all, it is the sense of pride associated with its place on sports jerseys, and in the names of national teams such as netball’s Silver Ferns, and rugby's Black Ferns (women) and the All Blacks (men), that gives the fern an unassailable place in New Zealand’s culture.


External links and sources

More suggestions and sources


How to cite this page: Patrick Brownsey, 'Ferns and lycophytes', Te Ara - the Encyclopedia of New Zealand, http://www.TeAra.govt.nz/en/ferns-and-lycophytes/print (accessed 18 November 2019)

Story by Patrick Brownsey, published 24 Sep 2007