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Botanical Discovery in New Zealand: The Resident Botanists

Leonard Cockayne (1855–1934)

Leonard Cockayne (1855–1934)

Like Colenso, Leonard Cockayne came to New Zealand as a young man. He was born at Norton Lees, Derbyshire, where as a child he became interested in plants. He not only pressed flowers to make specimens but was also a keen gardener. From school he went to Wesley College, Sheffield, and then to Owen's College, Manchester, and studied chemistry, botany, and zoology as a preparation towards taking a degree in medicine. But he did not complete his medical course.

He left England in 1879, stayed in Australia for some months teaching, and then moved on to New Zealand, arriving here the following year. He was on the staff of the Tokomairiro District High School from 1881 to 1885. He then moved to Christchurch and established a garden near New Brighton. He bought a piece of land, about four acres, and in the next twelve years, doing everything except the rough digging himself, stocked it with native and exotic plants. These were carefully labelled and their growth and leaf changes watched and recorded. He exchanged plants and seeds with gardeners and botanists all over the world, receiving every year the seeds of several hundred species and sending away even more.

Then, when he was over forty, and had this sure foundation of knowledge of plants and their habits, he began to study intensively the native New Zealand flora. For the next thirty-six years he was carrying out field investigations and publishing the results of his studies.

The first result of his field work was an account of the regrowth of scrub and forest after fires. Cockayne spent six weeks page 21
Leonard Cockayne (1855–1934)

Leonard Cockayne

on the summit of Arthur Pass taking notes on the effects of two fires which had destroyed large areas of the vegetation there, one seven years before and the other some time earlier. Arthur Pass is on the dividing line between two very different types of forest. On the Westland side is a mixed rain forest without beech. There is a luxuriant growth of many kinds of trees and an abundance of undergrowth, largely ferns. On the Canterbury side the forest trees are almost entirely mountain beech, the few other kinds including the mountain toatoa. Cockayne set himself the task of finding out what species the scrub had contained before the fires took place and in what order and quantity the species reappeared in the burnt-out area. He found that shrubs which appeared quickly and in large numbers included tauhinu (Cassinia vauvilliersii), box-leaved koromiko (Hebe buxifolia), Coprosma parviflora, Aristotelia fruticosa, and Hebe vernicosa—all species now well known as plants which soon occupy cleared scrubland. Cockayne also noticed that some kinds, such as Celmisia armstrongii and the mountain flax, became more abundant than formerly, and that one species of tree, Dracophyllum traversii, was completely killed out by fire.
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A twig of Hebe armstrongii (life size) showing the cypress-like leaves of the adult plant

A twig of Hebe armstrongii (life size) showing the cypress-like leaves of the adult plant

Cockayne made good use of his garden, and in some cases the gardens of his friends, for growing the seeds of native plants. He carefully described and illustrated with his own drawings a considerable number of seedlings of New Zealand plants, and published three papers on them in the Transactions of the New Zealand Institute. Many interesting facts came out of his studies. For instance, he found that, in one of the whipcord koromikos, Hebe armstrongii, which in the adult stage has small thick closely compacted leaves like those of a cypress, the first leaves of the seedlings are quite unlike those of the adult shrub: they are flat like ordinary leaves, and variously lobed. Succeeding leaves are narrow and without lobes, and these are followed by the small overlapping leaves of the mature plant. Such a life history he explained by assuming that the whipcord koromikos have arisen from plants with ordinary flat leaves, living in a moist climate, by a gradual reduction of the leaves in the course of a change to a dry, cold climate (as a means of protecting the plants from loss of water). These plants have retained their small leaves because they still live under the dry, cold conditions of mountain climates.

These investigations were only preliminary studies for the more comprehensive work Cockayne had in mind. He wanted to find out the relation of plants to their environment, not only in the main islands of New Zealand, but in the small outlying islands to the south and east, which few botanists had visited. This, of course, meant a tremendous amount of work in the field, gathering specimens far from established roads and tracks and noting the page 23
Seedling leaves of Hebe armstrongii: left, early seedling leaves; right, later seedling leaves, showing transition between early seedling and adult leaves (all six times life-size)

Seedling leaves of Hebe armstrongii: left, early seedling leaves; right, later seedling leaves, showing transition between early seedling and adult leaves (all six times life-size)

types of places where they were found; and indoors, sorting, classifying, and deciding the relationship of each plant to the region where it grows.

Next Cockayne explored the basin of the Waimakiriri river, from the Canterbury Plains to the mountain tops, collecting specimens. As a result he was able to define botanically four regions—lowland, lower mountain, subalpine, and alpine. In each of these regions he made a list of the plant formations—forest, scrub, meadow, swamp, sand-dune, and so on—but in most cases he published the name of only the dominant species in each formation.

Then he decided to go to the Chatham Islands to study the plant formations, the forms of the plants under the varied conditions existing there, and the changes brought about by human settlement. This sparsely settled group of islands had been visited as far back as 1840 by Dieffenbach,* who made a small collection of plants there, and again in 1863, when H. H. Travers made a considerable collection of plants;** but little else about its botany was known before Cockayne spent six weeks there in 1901. He was helped a great deal by Mr F. A. D. Cox, an ardent plant collector who lived there.

Cockayne worked through the plant formations on the largest island (Wharekauri, or Chatham), from the coast to the southern tableland, where he camped for eleven days. The tableland is the highest point on the island and the part on which vegetation is least altered by the presence of man and introduced animals. Here he found very interesting bog formations. The soil is peaty and covered by the hummocky bog moss (Sphagnum); through this grow a large sedge (Lepyrodia traversii), a beautiful daisy

* Dr Ernst Dieffenbach was surgeon and naturalist to the New Zealand Company 1839–40.

** These were described by Baron Mueller in The Vegetation of the Chatham Islands (1864).

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The outlying islands of New Zealand which Cheeseman and Cockayne explored botanically.

The outlying islands of New Zealand which Cheeseman and Cockayne explored botanically.

shrub with purple flowers (Olearea semidentata), a small shrubby grass-tree(Dracophyllum paludosum), and various other plants. The forest growing on this tableland is itself boggy and it is especially characterized by the presence of a daisy tree with yellow flowers(Senecio huntii) and a broad-leaved grass-tree (Dracophyllum arboreum).On the lowlands the common trees are the karaka and a koromiko (Hebe gigantea), the only true tree in that genus. Cockayne points out that according to geological evidence the Chatham Islands were once joined to the main islands of New Zealand; it would be then that they received their plants.

Two years later, in the middle of winter, Cockayne, in his enthusiasm for studying the plant formations of country almost botanically unknown, set out for the Southern (Subantarctic) Islands on the Government steamer Hinemoa. The ship had to spend several days at Port Pegasus, Stewart Island, waiting for favourable weather, and owing to heavy seas no one could land on page 25 the Snares; but landings were made on the Auckland, Campbell, Antipodes, and Bounty Islands. Despite the weather, Cockayne was able to collect samples of the plant covering on each of these islands, and thus was able to write a fairly complete account. He added to his and our knowledge of the vegetation of these bleak islands when he visited them again at the end of 1907.

Cockayne found that the plants of the subantarctic islands belong chiefly to species that are also found on the main islands of New Zealand. There are, however, some very remarkable kinds not found elsewhere.Pleurophyllum is a genus consisting of three species of daisies found only in the Southern Islands. The plants are two feet or more tall and bear upright racemes of large flowerheads with purple petals, though in two of the species the petals are inconspicuous. The Snares taipari(Olearia lyallii), also found on the Auckland Islands, is a small tree with large serrated leaves, pure white underneath. There are two species of plants belonging to the carrot family(Anisotome latifolia, A. antipoda), which have large divided leaves two feet long and flowering stems twice this height. Then there are plants belonging to the Aralia family, with very large kidney-shaped leaves, Stilbocarpa robusta on the Snares and S. polaris on the other islands.The Maori name for plants of this genus is ponui.Lastly may be mentioned a blue-flowered koromiko(Hebe benthami), and a mountain daisy(Celmisia vernicosa) with a rosette of hard shining leaves.

Cockayne's method of studying plants in relation to their surroundings introduced to New Zealand a branch of botany hitherto untouched here—the science of plant ecology. This deals with the variation in plant structure according to climate and soil, and with the distribution of plants as determined by the same two factors. All these bring about definite societies or formations (such as forest, scrub, swamp, and so on) of plants. ‘Plants are not scattered haphazard over a region, but occur in definite associations, which have been thus grouped in consequence of climate, the nature of the soil, the geological history of the land, the reaction of one plant upon another when brought into contact, and the presence of certain animals. Such groups of plants are called “plant formations”, and these make up the vegetation of a region just as do the species of the flora. To find out how such formations have originated, tracing their evolution, and studying the adaptations of their members to their surroundings, is one of the most important functions of botany, and has great bearings on agriculture, horticulture, and forestry.*

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Sand-dunes (lower right) advancing over a plantation of introduced trees

Sand-dunes (lower right)
advancing over a plantation of introduced trees

Next Cockayne published an account of the coastal vegetation of New Zealand. He then made for the Government a series of botanical surveys on the reserves and parks of Kapiti Island, Waipoua Kauri Forest, Tongariro National Park, and Stewart Island, and on sand-dune vegetation. These were issued by the Lands and Survey Department as Parliamentary Papers in 1907, 1908, and 1909, and were comprehensive reports, illustrated with photographs, on the vegetation. They contain some of Cockayne's best botanical work, and, indeed, formed models for other botanists.

His Report on the Dune-Areas of New Zealand was particularly important. There are large areas of sand-dunes in New Zealand, altogether about 314,000 acres, mainly (290,000) in the North Island. Sand-dunes naturally occur for the most part along the sea coast where there is a perennial source of sand. This is blown from the beach towards the land and accumulates in shifting hummocky dunes that may extend to a mile or more from the shore. Where there is not a sufficient covering of plants the wind page 27 continually moves the sand inland, and gradually it will bury the country, with its vegetation, that lies in front of it. It is therefore necessary, if possible, to bring the dunes to a standstill so that plants can grow on them. The only practicable way of doing this, as Cockayne pointed out, is to plant the dunes with species that are adapted to grow in sand and then, on the more fixed soil that is thus created, to grow trees, especially the fast-growing kinds such as the Monterey pine (Pinus radiata).*

Cockayne soon began to publish books, both popular and technical, on the plants of New Zealand. His first venture was New Zealand Plants and their Story, which appeared in 1910. Second and third editions, much enlarged, have since been published. This book gave a clear and vivid account of botanical exploration, of the plant formations, of naturalized plants, and of cultivated plants.

But Cockayne was at this time working on a much larger and more technical book, which he called The Vegetation of New Zealand. It described the plant formations of the main island and of the outlying islands. The first part is arranged under the headings ‘Vegetation of the Sea Coast’, ‘Vegetation of the Lowlands’, and ‘Vegetation of the High Mountains’, and under each heading are included descriptions of the most important plants and of the plant formations. Other chapters deal with botanical exploration, the effect of settlement, botanical districts, and the relationships of the flora with those of other countries. The manuscript of this important work was ready about 1914, but printing was held up by the first world war and the book did not appear until 1921. It was printed in Germany and formed one of a series called Die Vegetation der Erde. A second and much enlarged edition of The Vegetation of New Zealand appeared in 1928.

Cockayne's fertile mind led him along many new lines of investigation. This is particularly well shown in a paper** on the evolution of plants in New Zealand. In this he illustrated such subjects as variation in form, response to the conditions of the surroundings (such as climate and soil), crossing of species, the different forms of seedling leaves, and the distribution of species within New Zealand.

Next Cockayne undertook an investigation for the Department of Agriculture. In areas of low rainfall, as in Central Otago, much of the country between 600 and 3,000 feet above sea

* See Post-Primary School Bulletin Vol. 3 No. 4 Sand-Dune Plants.

** Published 1912 in the Transactions of the New Zealand Institute

page 28
Tussock grassland, Central Otago, showing contrast between land fenced off from sheep and rabbits, and land open to them

Tussock grassland, Central Otago, showing contrast between land fenced off from sheep and rabbits, and land open to them

level has lost its original covering of tussock grassland by overgrazing by sheep, by burning,* and especially by swarms of rabbits eating the plants and burrowing in the ground. In some places there is very little vegetation other than cushion plants called scabweed (Raoulia). Cockayne was to find out whether these areas could be restored. First he had to discover which plants sheep prefer. He noted that they greedily eat soft-leaved grasses, which include the introduced kinds, but avoid hard-leaved species, which include some of the native tussock grasses.

Cockayne carried out experiments in two ways, firstly by spelling, that is by fencing out the sheep and rabbits to see whether the vegetation would recover by itself, and secondly, by fencing as before and by sowing the seeds of various grasses and other fodder plants. The experiments were carried out for a few years only, but showed that spelling alone resulted in the recovery of certain plants in favourable areas. Sowing, however, produced better results though only in favourable situations. Cockayne could not carry out the experiments long enough to make a thorough test of regrassing. His investigations were completed in 1920. Since then a great deal of work has been done on grasslands in New Zealand by officers of the Department of Agriculture.

* Though fresh tender growth springs up after burning, sheep and rabbits eat this so avidly that they quickly destroy this new covering.

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From about 1920 onwards Cockayne spent a good deal of time studying hybrids (crosses between different kinds of plants). Some botanists have maintained that new species commonly arise by hybridization, but Cockayne did not accept this theory; he believed that hybridization explained the fact that many species exist in a large number of different forms. He first became convinced that there were hybrids between native plants when he was studying beech forests, for he observed that some mature trees possessed characters intermediate between the recognized species, and that, where there were numerous seedlings, every stage between the shapes of the leaves of the species present was found in the seedlings. This discovery was the beginning of investigations into the extent of hybridism in New Zealand plants. For the next ten years Cockayne and his fellow-worker H. H. Allan investigated, and published articles about their work on, hybrids in the New Zealand flora. These hybrids are plants which, especially
Red Beech

Red Beech

Mountain Beech(1811–1899)

Mountain Beech(1811–1899)

Red Beech (Nothofagus fusca), Mountain Beech(N. cliffortioides) and their hybrids

Red Beech (Nothofagus fusca), Mountain Beech(N. cliffortioides) and their hybrids

page 30 in the shape of their leaves, are intermediate between their probable parents, which are found growing with them; they are almost always found in places where both parents are still, or recently have been, present.

Cockayne's contributions to forestry were notable. He made a special study of beech forests, and wrote a monograph about them. This was issued in 1926 and 1928 in two parts, one on the ecology and the other on various economic aspects such as milling, fire protection, and value of beech timber. Cockayne, with Esmond Atkinson, published a paper on the wild hybrids of the beeches, and, with E. P. Turner, an illustrated book on The Trees of New Zealand. Lastly, his gardening experience with native plants was condensed in a small book The Cultivation of New Zealand Plants published in 1923.

A passage from this book shows his enthusiasm. ‘Our flora is famous the world over. Nor is this to be wondered at when it is remembered that more than four-fifths of the flowering plants are to be found growing wild in no other land; they are, indeed, true New Zealanders. Then there is the array of forms these plants have assumed, so distinct and betraying such different origins. What a surprising plant-population is this of the isolated antipodean land, embracing, as it does, amongst its members, great treedaisies, giant yellow and white buttercups, arboreal lilies, bayonet-like spaniards, yellow and bronze forget-me-nots, huge mountain marguerites, vegetable-sheep, evergreen trees of many kinds, shrubs of varied aspects, and the dainty herbaceous, or partly woody plants—most precious of all—which dwell near the perpetual snows.’

We might summarize Cockayne's achievements in this way:

He introduced to New Zealand the study of seedlings and the changes which they go through before reaching the adult form.

His investigation of the vegetation of Arthur Pass after burning was the first study made in New Zealand on the succession of plant formations in a given area.

He introduced to New Zealand the study of the relations of plants to their surroundings (ecology).

He discovered the fact that hybridization is common among the native plants of New Zealand.

His report on sand-dunes gave an account of the conditions of plant life in these areas, and pointed out that the dunes page 31 could be arrested and reclaimed by planting trees, especially pines.

He made a comprehensive study of the over-grazed areas of Central Otago and published much useful information on the subject.

He wrote on the ecology of beech forests and discussed the practical bearing of this on their management.

He studied the distribution of the native plants within New Zealand, and published maps of the botanical districts which he defined.

These achievements made a contribution to New Zealand botany that has had a permanent and ever-widening influence on the study and teaching of the subject. Up to his time practically all the published work on the New Zealand flora had been on plant classification, but Cockayne broke new ground in several directions. It is this which gives such great importance to his work. It has, indeed, resulted in notable advances in several fields of study, particularly in ecology.

Cockayne concentrated on the study of plants growing in their natural surroundings and described what he saw in
Cockaynea GracilisRedrawn by Richard Sharell, after John Buchanan

Cockaynea Gracilis
Redrawn by Richard Sharell, after John Buchanan

page 32 language that could easily [gap — reason: unclear] by both the professional botanist and by the person with [gap — reason: unclear]knowledge of botany.

During his numerous journeys Cockayne made a fairly large collection of dried [gap — reason: unclear] he used for comparison when he found something that [gap — reason: unclear] to him to be unusual. This collection has been added to the herbaria of the Auckland Museum and the Dominion Museum.

High honours came to him for his scientific work. He was elected a Fellow of the Royal Society of London in 1912; and he was awarded four medals: the Hector and Hutton medals of the New Zealand Institute, the Darwin medal of the Royal Society of London, and the Mueller medal of the Australasian Association for the Advancement of Science.

Cockayne's name is commemorated in a genus of New Zealand grasses, Cockaynea, containing two species. Nine species of New Zaland plants also bear his name. Among these are a koromiko (Hebe cockayniana), an eyebright (Euphrasia cockayniana), a mountain daisy (Celmisia cockayniana), and the mountain Astelia (A. cockaynei).

Cockayne was a man of untiring energy, forceful character, and decisive judgement. Professor Tansley (then Professor of Botany at the University of Cambridge) said of him: ‘Cockayne's vigorous, indefatigable personality, combined as it was with complete sincerity of mind, wide outlook and particularly acute powers of observation and memory that make the born field naturalist, were devoted to a flora and vegetation of great richness and unique interest at a time when it was still largely unspoiled by human interference’; and again, ‘Leonard Cockayne played the most conspicuous part in the development of modern field botany in the British Empire during the first third of the twentieth century.’ His personal character is thus summed up by his friend R. M. Laing: ‘A few words must now be said on Cockayne the man, and some attempt be made to show wherein lay his greatness. He was an open, challenging, enthusiastic spirit, consumed almost entirely by the desire to advance New Zealand's botanical knowledge. One of his, most obvious characteristics was his refusal to accept the statements of previous workers in his own field without critical investigation. When he could disprove the generalization of a predecessor he was delighted. Combined with this sceptical attitude was a remarkable fertility of imagination. One rarely met him without finding that he had some new ideas to unfold. Some of these were perhaps fantastic, and had to be cast aside on fuller investigation; but many of them led to fresh and fruitful fields of work.’