Ferns: the glory of the forest
In few of the world’s temperate forests do ferns assume the luxuriance and dominance that they achieve in the damper portions of the New Zealand bush. Fronds decorate every tree-trunk and choke the floor of the forest, while stands of huge tree ferns tower over lesser trees. Little wonder that the fern frond has become a major symbol of the country in popular culture.
Ferns have an appeal that transcends culture and climate. In Polynesia they adorn the head-dresses of indigenous people, in Asia young shoots are offered as delicacies in open-air food markets, and in Australia gardeners insist on growing them in the most arid environments. In earlier times, Victorian England went crazy over ferns (see sidebar, page 79), Melanesians carved statues from tree-fern trunks and Maori made the koru, the uncurled fern shoot, a dominant feature of their art. Today, the fern is an iconic element in New Zealand’s national identity, featuring on stamps, coins, banknotes and the national coat of arms. But, above all, it is the sense of pride associated with the fern-branded All Black rugby jersey and national teams such as the Silver Ferns (netball) and Black Ferns (women’s rugby) that gives the fern an unassailable place in New Zealand’s culture.
Just what is it about ferns that captures our imagination? Probably not their ancient lineage, stretching back far beyond dinosaurs to a time that is impossibly distant for most people’s comprehension. Is it their sheer diversity of form, then, or the natural grace of their curving fronds, or the fascination of an uncoiling fiddle-head that is the secret to their appeal? Or do names such as “adder’s tongue,” “moonwort,” “maidenhair” and “spleenwort” appeal to our psyches by hinting at secret uses in a mystical past? Whatever the reason, ferns today enjoy a popularity among plant-lovers that is rivaled only by orchids and roses.
When asked the botanical characteristics of ferns, most people will answer that they have highly divided leaves and lack flowers, and some will suggest that they reproduce by producing copious quantities of dust-like spores, rather than by fruit or seeds. These answers are all correct, but they fail to adequately distinguish ferns from other plant groups. Mosses and liverworts, for example, often share these same features.
The distinguishing features of ferns are obscure and not readily obvious to the casual observer. Ferns have intricate life cycles and, unlike all other land plants, pass through two quite separate free-living stages: a spore-bearing stage and a very different sexually reproducing stage. Plants loosely referred to as “ferns” (but more correctly called pteridophytes) actually encompass several distinct groups that share the characteristics of reproducing by spores and having a life cycle involving two separate stages. In addition to the true ferns, there are fork ferns, clubmosses, spikemosses, quillworts and horsetails that are collectively known by the title “fern allies.”
The true ferns form the vast bulk of pteridophytes and are distinguished by having large leaves or fronds with branching veins, and by having their spore-bearing structures (known as sporangia) on the margins or undersides of the fronds.
Clubmosses, spikemosses and quillworts together belong to the lycopods and are characterised by having small leaves spirally arranged around the stem, each with a single unbranched vein, and sporangia that are borne on the upper surface of the leaves.
The fork ferns form a small group with very reduced physical appearance—they have no true roots or leaves, and the sporangia are fused into groups of two or three.
Finally, there are the horsetails, a small group that no longer occurs naturally in New Zealand, but which is represented by a few introduced species that have jointed stems, whorled leaves and sporangia borne in specialised cones.
The typical fern you see in bush or garden is the sporophyte stage of the fern life cycle. However, when the tiny, single-celled spores which it produces are blown away by the wind and land on moist soil, they germinate into a plant of quite different appearance. This is the gametophyte stage (also known as a prothallus), in which sexual reproduction occurs.
Prothalli are tiny plants, frequently less than a centimetre long. They are usually heart-shaped, with almost no structure. They grow flat on the ground, anchored there by a few hair-like outgrowths, and produce sex organs on their undersides. The male structures (known as antheridia) are small protruberances that eventually burst to liberate a mass of corkscrew-shaped sperm cells. These cells have numerous beating hairs that enable them to swim in a film of moisture towards chemical attractants released by the female organs. Fertilisation occurs when the sperm cells enter the minute flask-shaped female structures (known as archegonia) and fuse with the egg cells. The fertilised egg cell then develops rapidly into a new sporophyte fern plant, while the prothallus usually dies, its task of sexual reproduction complete.
The prothallus stage is rarely seen in the wild, but can be readily observed in cultivation by simply sowing a few spores onto damp, sterilised soil. The prothalli will develop within a few weeks as long as the soil doesn’t dry out. There is a surprising amount of diversity in these tiny plants. While most are heart-shaped, surface-living and short-lived, some grow below ground, lack green photosynthetic pigments and develop an association with a fungus in order to obtain water and nutrients. Others are linear or strap-shaped and continue growing on the soil surface for more than one season. A few, like species of the filmy fern Trichomanes, consist of branching filaments and more closely resemble a fuzz of green algae than a fern gametophyte.
As if spores for dispersal and sexual reproduction were not enough, many ferns and fern allies also have asexual means of reproduction that bypass one or other of the generations. The most familiar is the production of bulbils by the hen and chickens fern (Asplenium bulbiferum). The bulbils are miniature plants that grow out directly from the cells on the upper surface of the frond. They initially produce tiny leaves while still attached to the parent frond, but later develop rootlets when they come in contact with the ground, either after being knocked off or when the frond droops enough to touch the soil. They are genetically identical to the parent fern, developing into new fern plants without any act of sexual reproduction.
Similar plantlets are produced by the walking fern (Asplenium flabellifilium). In this species, the frond usually produces a single bulbil at the very tip, so that when it arches over and touches the soil, the bulbil roots and grows out into a new plant. In this way, the fern appears to “walk” along the ground. This growth habit makes it an excellent subject for a hanging basket.
The lance fern (Anarthropteris lanceolata) produces new plantlets directly from its roots, and on wet rock faces colonies of plants can often be seen linked together in a long string. The tuber sword-fern (Nephrolepis cordifolia) produces small, potato-like tubers on its roots that will grow out into new plants. The crown fern (Blechnum discolor) produces short stolons from its rhizome, just like a strawberry plant, and each one can give rise to a new plant so that the fern often dominates a large area of ground. The moonwort (Botrychium lunaria) produces small reproductive bodies called gemmae on its rhizome. These are usually rounded structures of just a few cells that are often left behind in the soil if the plant is disturbed and are each capable of developing into new plants.
More familiar is the wheki or rough tree fern (Dicksonia squarrosa), which produces buds on its trunk. If the crown of the fern is damaged, these buds will grow out to replace it and may even give rise to a multiheaded tree fern. Wheki trunks are often cut at the top and bottom to remove fronds and roots, and then sold by garden centres for use as retaining walls. However, such is their regenerative power that the trunks sometimes grow new roots and fronds; the seemingly dead wall comes to life.
Asexual reproduction is not confined to the sporophyte generation. Gemmae are also formed on the gametophytes of several ferns, especially those that consist of branching filaments, such as the finger ferns (Grammitis species) or some filmy ferns (Trichomanes species). In these cases, however, they develop into new gametophytes, not new sporophytes, but they are just as effective a means of dispersal.
Some 226 species of pteridophytes are known to occur in the wild in New Zealand. Of these, 194 are native species and 32 are believed to have been introduced since European colonisation but are now established in the wild. The number continues to increase each year as new species are recognised or new introductions are found.
Filmy ferns (species of Hymenophyllum and Trichomanes) are the largest, and one of the most attractive, groups of New Zealand ferns, with 27 species. As their name implies, they have delicate fronds that are only one or two cells thick, and when viewed against the light display a wonderful range of shades of green. They lose water easily and therefore require an environment of high humidity in which to thrive, growing best in damp forest.
The kidney fern (Trichomanes renifirme), with its extraordinarily shaped frond, projecting clusters of sporangia on the margin and yellowish green colour, is a plant of international repute that never ceases to attract attention from visiting botanists. The sheer size of species such as Hymenophyllum dilatatum and H. demissum is also impressive for filmy ferns in a temperate climate.
At the other end of the scale, the filmy ferns include two of New Zealand’s smallest ferns. Hymenophyllum armstrongii has a frond that is only 2 cm long and 3 mm wide when growing luxuriantly, and, not surprisingly, it is frequently overlooked in its characteristic habitat amongst epiphytic mosses on branches of forest trees. Hymenophyllum minimum is scarcely any larger, but is more easily found growing on damp faces of exposed rocks amongst moss.
Hard ferns (Blechnum) are the next most diverse group, with 23 species. Several species produce young fronds that are tinged pink when first formed, and a bank of young Blechnum plants in spring can be a glorious sight. Kiokio (Blechnum novaezelandiae) is probably one of the commonest ferns in New Zealand and, because of its habit of growing abundantly on roadside cuttings, it should be familiar even to those who never step out of their cars for a closer look.
Spleenworts (Asplenium), with 18 species, are another distinctive group in New Zealand. Although they are characterised by the herring-bone pattern formed by the clusters of sporangia extending along the veins of the fronds, individual species can be hard to distinguish. Many are widespread, very variable in form and prone to hybridise in disturbed habitats. The hen and chickens ferns, shining spleenwort (Asplenium oblongifolium) and hanging spleenwort (A. flaccidum) are some of the better known species.
The largest ferns in New Zealand are the tree ferns. With a tall woody trunk up to 20 m in height and graceful arching fronds forming an umbrella-like canopy, the mamaku (Cyathea medullaris) is a truly spectacular plant, and a stand on a hillside is one of the more evocative sights in the New Zealand landscape. Our national emblem, the silver fern (C. dealbata), is a much shorter, sub-canopy species, but the remarkable white underside to the frond makes this an unforgettable fern.
Two species, wheki-ponga (Dicksonia fibrosa) and the soft tree fern (Cyathea smithii), are renowned for the skirt of dead fronds that surrounds their trunks. The latter species also has the distinction of being the southernmost tree fern in the world, growing on the Auckland Islands at 50° S.
Fern allies include 10 New Zealand species of clubmosses, which fall into two main groups based on growth form. The hanging clubmoss (Huperzia varia) forms long tassels from the bases of Collospermum or Astelia clumps growing high in the crowns of forest trees. Other clubmosses, such as waewaekoukou (Lycopodium volubile), spread along the ground or scramble through scrub.
Some have specific habitat requirements. Puakarimu (Lycopodium deuterodensum) is largely confined to kauri forest, and the bog clubmoss (L. serpentinum) to a few swamps in the far north, where it is now a very rare plant.
Another very rare fern ally is Phylloglossum drummondii, a plant confined to gumlands north of Auckland. It emerges above ground only in the winter months, and survives underground in the summer as a tuber. It seems to prefer recently burnt areas under short scrub where there is little competition from other plants.
Umbrella ferns are quite unlike any other fern. Rather than producing a typically divided frond, the midrib divides repeatedly into two, producing a bud at the end of each branch, with two new branches arising immediately below it. Lateral branching of this sort can be finite, producing a distinctive shape, as in the umbrella fern (Sticherus cunninghamii), or it can continue almost indefinitely, with the frond forming extensive thickets, as in the tangle fern (Gleichenia dicarpa). In both cases, the buds can grow out to form new tiers of branches, contributing to the tangled thicket of the latter species and adding additional layers of “umbrellas” to the former.
Comb ferns are equally distinctive in being the only ferns in New Zealand in which the stalk of the frond (the stipe) is much longer than the leafy blade (the lamina) and often forks several times. The lamina is usually tiny, and the paired segments are infolded on one another to give the frond a one-sided appearance, not unlike that of a comb. Equally odd is the fact that the “leafy” part of the frond is usually brown, whereas the stipe is green—the reverse of most ferns.
The adder’s tongue is truly strange, and has little outward resemblance to other ferns. The “frond” consists of an undivided leafy blade and a fleshy spike on a long stalk that comprises two rows of fused sporangia. Usually only one or two fronds are produced each season, and the young developing fronds emerge erect or merely bent over, not tightly coiled in a crozier, as in all other ferns. Species of Ophioglossum are believed to be very primitive.
Despite New Zealand’s reputation as a country rich in ferns, the total of 226 species is not great when compared with neighbouring tropical areas. Fiji, for example, which has a much smaller land area, has over 300 species, and Queensland almost 400. What New Zealand lacks in species diversity it more than makes up for in abundance. In few other parts of the world, particularly in temperate regions, are ferns such a large component of the vegetation.
Pteridophytes occur throughout New Zealand and can be found in almost all terrestrial and freshwater habitats except the very highest alpine regions. In open coastal situations they are more scarce, but a few species have thick, fleshy fronds which can tolerate sun, salt spray and dessication. Blechnum blechnoides, B. durum, Asplenium appendiculatum and the shore spleenwort (A. obtusatum) can all be found in damp seepages on exposed coastal cliffs, while, slightly further from the sea, the leather-leaf fern (Pyrrosia eleagnifolia) climbs over bare rocks by means of its long creeping rhizomes. Its fleshy undivided frond, densely covered in fawn hairs on the lower surface, is admirably adapted to cutting down water loss in this arid environment.
In dry rocky habitats away from the sea, especially on the eastern side of the South Island, another characteristic assemblage of ferns can be found. This includes the rock fern (Cheilanthes sieberi), woolly cloak fern (C. distans), blanket fern (Pleurosorus rutifolius), and Pellaea calidirupium. Unlike those on the coast, these ferns seem strangely delicate for such a dry habitat, but they all have strategies for coping with moisture loss. The woolly cloak fern and blanket fern are abundantly covered in hairs or scales that reduce transpiration, while the rock fern protects its young developing sporangia by curling up its frond as the season progresses. Both it and Pellaea calidirupium can tolerate severe drought by dropping their fronds completely and surviving as an underground rhizome deep among rocks and in crevices.
Forest offers far more opportunities for fern growth. Here ferns can find niches on the ground, on stream banks, as sub-canopy species, as fully emergent species, or as epiphytes and climbers. Some, such as hound’s tongue fern (Microsorum pustulatum) and the shield ferns (Polystichum richardii, P. vestitum) prefer the forest margins, where light levels are higher; others, such as Blechnum nigrum, are found only in the darkest parts of the forest. Ferns such as the common maidenhair (Adiantum cunninghamii) and the velvet fern (Lastreopsis velutina) occur only in lowland or coastal forest, whereas Microsorum novae-zealandiae and the mountain tree fern (Cyathea colenso:) are confined to montane forest.
While some species are very site-specific, others occupy a wide range of habitats in many different types of forest. Two tree ferns, the mamaku and the gully tree fern (Cyathea cunninghamii), are emergent species, while others, such as the soft tree fern, silver fern and wheki (Dicksonia squarrosa) are sub-canopy species.
Common ground species include hen and chickens fern, shining spleenwort, hairy fern (Lastreopsis hispida) and gully fern (Pneumatopteris pennigera). Asplenium hookerianum, Lastreopsis glabella and the button fern (Pellaea rotundifblia) are found among the roots of large trees and on rocky ground. The banks of watercourses are home to three characteristic hard ferns—nini (Blechnum chambersi:), kiwakiwa (B. fluviatile) and Blechnum colensoi—and at higher altitudes the magnificent prince of Wales feathers fern (Leptopteris superba) grows at its very best in a permanently damp, dark environment.
It is the abundance of ferns as epiphytes in wet forest that really gives the New Zealand bush its distinctive character. Filmy ferns abound in this environment, and it is not hard to find a dozen or more species growing in close proximity. Finger ferns (species of Grammitis), hanging spleenwort, sickle spleenwort (Asplenium polyodon), lance fern (Anarthropteris lanceolata) and fork ferns (species of Tmesipteris) are also common on tree-fern trunks or hanging from the branches of forest trees.
Climbing ferns are much less dominant in New Zealand bush than in tropical rainforest, but mokimoki (Microsorum scandens), Rumohra adiantiformis and thread fern (Blechnum filifbrme) are common throughout, while jointed fern (Arthropteris tenella) and mangemange (Lygodium articulatum) are characteristic of the warmer northern forest.
The thread fern is an unusual plant, beginning life on the ground where it scrambles around until it finds a trunk to climb. Until this stage, it produces only short fronds with almost rounded segments, but as it grows upwards it produces larger and larger fronds with much more elongated segments. Finally, usually well above head height, it produces fertile fronds and then appears so different in form from the plant that started life on the ground that people often mistake them for different species.
Mangemange also has a curious growth form. Most climbing ferns ascend by means of a very long creeping rhizome which produces fronds as it grows upwards. In mangemange, however, it is the fronds themselves which have unlimited growth, twining upwards to form dense tangles of growth which were used by early bushmen as rough mattresses because of their springy nature.
As with ferns in the harsher environment of the coast, those in the forest also have different strategies for survival and have adapted to different microhabitats. Wheki, for example, often forms extensive groves as a result of the buds on its trunks and roots. Within these groves, dead fronds pave the ground, and, because they decompose only very slowly, tend to smother any developing seedlings and discourage competition from other plants.
Epiphytes, too, compete for space. The luxuriance of epiphytic growth is much more structured than initially appears the case. Kidney fern and lance fern, for example, are found only as low epiphytes, where the amount of moisture is usually greater. Plants occupying higher branches have less moisture available to them, and so it is unsurprising to find the leather leaf fern, which can exist on dry coastal rocks, also living happily as a high forest epiphyte.
Filmy ferns belie their delicate appearance by tolerating a remarkable amount of desiccation. A few species, such as Hymenophyllum malingii, are almost totally covered in hairs. Others, such as Hymenophyllum ferrugineum, grow predominantly on tree fern trunks and reduce transpiration by producing fronds that overlap one another in a similar way to what seaweeds do when the tide has gone out. Additionally, most have fronds which curl up dramatically in dry weather, thus reducing the surface area from which water can be lost.
Above the tree line, ferns become a much less important component of the vegetation. About 20 species, or 10 per cent of New Zealand pteridophytes, occur regularly in the alpine zone compared to more than 600 species of flowering plants (over 30 per cent of the total). Only the alpine shield fern (Polystichum cystostegia), bladder fern (Cystopteris tasmanica), mountain kiokio (Blechnum montanum), thousand-leaved fern (Hypolepis millefolium), finger ferns (Grammitispoeppigiana and G. giveni:), one filmy fern (Hymenophyllum villosum) and two clubmosses (Huperzia australiana and Lycopodium fastigiatum) are found primarily in this habitat.
Elsewhere, a handful of ferns are found in some specialised habitats. One family of ferns, the Dennstaedtiaceae, almost exclusively occupies disturbed ground. The best known examples are bracken (Pteridium esculentum), which occurs in areas that have been burnt or cleared, and pig fern (Paesia scaberula) which forms extensive colonies on reverting pasture.
The water fern (Histiopteris incisa) and several species of Hypolepis are opportunist species that get through their life cycle as quickly as possible. They germinate in disturbed soil, spread rapidly by means of aggressive and long-creeping rhizomes, and form highly-divided fronds. They cannot tolerate competition, and are quickly replaced by other colonising species which tend to shade them out. They disappear as quickly as they came, but liberate large quantities of spores which survive in the soil until future disturbance occurs, or disperse to freshly disturbed sites nearby.
Thermal regions are home to a few species of tropical origin that survive in New Zealand only in the very far north or in heated ground, where they are protected from winter cold. The fork fern (Psilotum nudum), Di cranopteris linearis, Cyclosorus interruptus and two undescribed species of Christella and Nephrolepis can be found around steam vents or along thermally heated stream banks in places such as Orakei Korako and Waimangu.
A few ferns are found in freshwater sites, but as with many plants that occupy such habitats their appearance is highly modified. Pillwort (Pilularia novae-zealandiae) and quillworts (species of Isoetes) are found in lowland lakes and alpine tarns, but their undistinguished grass-like leaves mean that they are easily overlooked.
Quillworts produce their spores in the swollen bases of their leaves, not releasing them until the leaves rot. Pillwort forms hard, bean-like reproductive capsules only when the tarn dries out, and its uncoiling fronds are therefore the only characteristics that betray its affinities to other ferns. Pacific azolla (Azolla filiculoides), on the other hand, is hard to miss, forming crimson-coloured floating carpets on the surface of slow-moving streams and ponds.
Over 30 ferns and fern allies have been introduced to New Zealand and are now established in the wild. Most are known only from isolated records, often as escapees from cultivation. However, some are potentially invasive and a few have become serious weeds. The most significant of these are African clubmoss (Selaginella kraussiana), which occurs widely along stream banks and in damp forest, where it displaces native ferns, mosses and liverworts, and common horsetail (Equisetum arvense), which is an extremely invasive weed of riverbank sites in high-rainfall areas.
Less threatening are the now widespread male ferns (Dryopteris affinis and D. filixmas), royal fern (Osmunda regalis), which is well established in swampy areas of the northern North Island, and the ferny azolla (Azolla pinnata), which is common in slow-moving freshwater in northern New Zealand. Potentially more serious is the kariba weed (Salvinia molesta), an aggressive weed of hybrid origin that clogs many tropical waterways, but one which has been largely eradicated in New Zealand by a combination of careful management and temperate climate.
Of the 196 native pteridophytes, 89 (or 46 per cent) are endemic—that is, they are found nowhere else in the world. By contrast, 84 per cent of seed plants are endemic to New Zealand. One reason for this disparity may be that ferns produce spores that are much lighter and more easily spread by the wind than the heavier seeds of flowering plants.
There is some evidence for this explanation in that fern distributions are generally broader within New Zealand than those of flowering plants. More than 50 per cent of New Zealand ferns have distributions that extend across more than half of both islands. Also, about a quarter of all seed plants are confined to one of nine geographical regions within New Zealand, but fewer than 10 per cent of ferns are confined to these same regions.
Fern distributions are, in fact, correlated quite strongly with temperature, rainfall and geothermal activity. While many species are widely distributed, some are confined either to the warmer northern, or to cooler southern, regions. Others occur either in the wetter west, or drier eastern parts of the South Island.
Most endemic species have a predominantly southern distribution pattern. They occur primarily in cool lowland to montane forest. By contrast, species with a predominantly northern distribution pattern include a large number of species that occur also in Australia and tropical parts of the Pacific.
The occurrence of tropical species in northern New Zealand leads to consideration of where our ferns have come from. Have they evolved here in the 85 million years since New Zealand split off from Gondwana and became effectively isolated from the rest of the world, or have their light spores enabled them to be blown across thousands of kilometres of sea to germinate and establish in the islands of the New Zealand archipelago?
There have been widely conflicting views on this issue, but increasingly the evidence seems to favour the idea that most of New Zealand’s ferns have blown here relatively recently. Some 94 of our 194 native species occur also in temperate Australia, Norfolk Island or Lord Howe Island. Another 56 species occur also in tropical Australia, south-east Asia and the Pacific, 15 are shared with southern Africa, and 14 occur as far away as South America and the circum-antarctic islands. These figures alone point strongly to the great mobility of ferns.
The presence of fossilised ferns in rocks millions of years old once encouraged the idea that they are plants of ancient lineage that could have been part of the landscape that rafted away from Gondwana. Elsewhere in the world clubmosses, for example, can be traced back to the Devonian period (355-410 million years ago), quillworts to the Carboniferous (290-355 mya), some groups of tree ferns to the Triassic (205-250 mya) and comb ferns to the Jurassic (135-205 mya).
However, recent molecular biological techniques, combined with fossil evidence, are starting to show that a large group of fern families (including spleenworts, hard ferns, finger ferns and many other characteristic New Zealand groups) had not even evolved by the time New Zealand split from Gondwana. Moreover, the absence or presence of spores preserved in various deposits of known age within New Zealand indicates that the first appearance of most ferns was well after the break-up of Gondwana. This evidence suggests that much of our internationally acclaimed fern flora may, indeed, have arrived here quite recently, and leads to the demoralising conclusion that it might comprise little more than the cast-offs of our trans-Tasman neighbour!
Whatever the truth about the origin of New Zealand’s flora, the undeniable fact is that this country has an extraordinary abundance of ferns that can be enjoyed by almost anybody of any age and fitness. For example, over 120 species, or around 60 per cent of the total flora, can be found in the Wellington region alone—an area that involves a drive of barely more than an hour in any direction. (By contrast, there are fewer species in the whole of Great Britain and Ireland combined.)
In many places around Wellington it is easy to find more than 50 species in one locality. An afternoon stroll to Butterfly Creek near Eastbourne, to the old Kaitoke Waterworks Reserve near Upper Hutt, or even around the Karori Wildlife Sanctuary right in the heart of the Capital, will provide the observant pteridologist with an abundance of species growing happily in their natural environment. Just down the road from the sanctuary, the enthusiast can find many more species that are not native to the Wellington region growing in the fernery at Otari Garden.
Perhaps my favourite haunt is a small patch of forest in the Akatarawa Ranges on the incredibly narrow and circuitous road between Upper Hutt and Waikanae. Here, near the summit at a spot known locally as Waterfall Creek, I have spent many hundreds of hours observing and marvelling at ferns, and introducing them to innumerable groups of botanists, students, amateur naturalists and visitors to New Zealand. The area is a steep-sided stream gully in kamahi forest, sufficiently high and shaded to be permanently cool and wet—a perfect environment not only for ferns, but also for mosses and liverworts.
In the space of no more than half a kilometre, one can see examples of almost the full range of New Zealand fern diversity. Tall, graceful tree ferns line the roadside; hard ferns, spleenworts and species of Lastreopsis adorn the stream banks; lycopods, umbrella ferns and kidney ferns occur on the drier ridge tops, whilst an extraordinary profusion of crepe ferns fills the damper gullies. Filmy ferns smother the trunks of almost every tree, and in the darkest, dampest corners of rock, among the glowworms sharp-eyed visitors can find little gems such as Trichomanes colensoi and T. endlicheriuanum.
Here, right by the roadside, almost literally at my back door, it is possible to get a genuine sense of the primeval vegetation that once clothed the whole of Aotearoa. I know of no other country in the world where ferns are so diverse, so luxuriant and so accessible to even the most casual observer, and it is easy to understand why they have become part of our national identity.