John Dawson & Rob Lucaswith Jane connoR

contributions by Patrick brownsey, shannel courtney, Peter de Lange,Phil Garnock-Jones, Mark Large, Don Morrisey, barry sneddon

new ZeaLanD’s

naTIVe TRees

To our grandchildren: Lucas and Noah Dawson;

Angelina and William Hayter; Grace and Francis Lucas

First published in 2011 by craig Potton PublishingReprinted 2011

craig Potton Publishing98 Vickerman street, Po box 555, nelson, new Zealand

www.craigpotton.co.nz

Text © John Dawson and Rob Lucas (unless specified otherwise)Photographs © Rob Lucas (unless specified otherwise)

Isbn: 978-1-877517-01-3 (standard edition)978-1-877517-65-5 (deluxe edition)

Publisher: Jane connoreditorial: Jane connor, sue hallas

Index: Diane LowtherDesign and layout: Jane connor, Tina DelcegPrepress: alan bridgland, spectra Graphics

cover typography: neil Pardingtoncover image: ‘Mist over Lake Mapourika’, © andris apse

Printed in china by everbest Printing co. Ltd

This book is copyright. apart from any fair dealing for the purposes of private study, research, criticism or review, as permitted under the copyright act, no part may be reproduced by any

process without the permission of the publishers.

The authors and contributors 7authors’ preface and acknowledgements 9Publisher’s preface and acknowledgements 10about the book 12 Map of the north Island 14Map of the south Island 15

InTRoDucTIon 17

conIFeRs 36Introduction to conifers 38Agathis 46Dacrycarpus 56Dacrydium 62Halocarpus 66Lepidothamnus 72Libocedrus 74Manoao 79Phyllocladus 81Podocarpus 88Prumnopitys 96

TRee FeRns 102Introduction to tree ferns 104Cyathea 110Dicksonia 118

FLoweRInG TRees 122Introduction to flowering trees 124Ackama 132Alectryon 136Alseuosmia 140Archeria 142Aristotelia 144Ascarina 147Avicennia 150Beilschmiedia 155Brachyglottis 160Carmichaelia 174Carpodetus 182

Clianthus 184Coprosma 188Cordyline 220Coriaria 230Corokia 232Corynocarpus 233Discaria 236Dodonaea 238Dracophyllum 240Dysoxylum 256Elaeocarpus 260Elingamita 264Entelea 266Fuchsia 268Geniostoma 270Griselinia 272Hedycarya 276Hoheria 278Homalanthus 290Ixerba 292Knightia 294Kunzea 298Laurelia 302Leptecophylla 306Leptospermum 308Leucopogon 312Litsea 314Lophomyrtus 317Macropiper 320Melicope 323Melicytus 326Meryta 336Metrosideros 338Mida 352Myoporum 354Myrsine 357Neomyrtus 369Nestegis 370Nothofagus 376Olearia 394Pennantia 436Pisonia 440

Contents

In keeping with its commitment to supporting science education, the Dick Roberts community Trust generously contributed the cost of donating copies of this book to all new Zealand secondary, intermediate

and composite schools to mark conservation week 2011. craig Potton Publishing wishes to also acknowledge the generous contribution from nelson Pine Industries to the costs of publication.

all other acknowledgements are on pages 9 and 11.

7

Pittosporum 442Plagianthus 463Planchonella 466Pomaderris 468Pouzolzia 472Pseudopanax 474Pseudowintera 498Quintinia 502Raukaua 504Rhopalostylis 508Schefflera 512Solanum 514Sophora 516

Streblus 530Syzygium 536Toronia 538Urtica 540Veronica 542Vitex 552Weinmannia 555

appendix 560Glossary 562bibliography and further reading 565Index 570

LIsT oF boxesbeech gaps 25new Zealand’s conifers 38Inside a kauri forest 48Kauri dieback 52epiphytes 54Freshwater swamp forests 58Rimu and kākāpo 65Identification: Libocedrus bidwilli and L. plumosa 78Identification: Mountain tōtara and lowland tōtara 94Identification: Cyathea and Dicksonia 104epiphytes on tree ferns 107Tree ferns 108Identification: hutu and pukatea 148The lifestyle and ecology of mangroves 152Tree daisies 160Magpie moth and Brachyglottis 171Pollination of kakabeak 185Domatia 189Tree species of Coprosma 190–1Identification: Coprosma arborea and C. spathulata 193stipules 199cabbage tree decline 224how cabbage trees make their trunks 225cabbage tree moth 229Pulvini 257caulifory and ramiflory 259

Pollinators of Hoheria 279Identification: Rewarewa and hīnau 297Kānuka and mānuka 301Trunk buttresses 305Mānuka blight 310Mānuka and mycorrhizae 311Kawakawa moth 322The māhoe stripper 334australian Myoporum 355sexual expression and flower variation in Nestegis 371Identification: black and white maire 373Inside a beech forest 378 –9Thieving from a thief 379Cyttaria fungus on silver beech 382Mistletoes 385what is treeline? 388scale insect—honeydew— sooty mould story 391hybrids in Olearia 399Moths and the twiggy olearias 428Plagianthus and Hoheria 465Five-finger as epiphytes 477Juvenile and adult forms 489Patē and five-finger 512Kōwhai caterpillar and moth 521witches’ broom on Streblus 533Tree nettle and butterflies 541Pūriri moth 554Tōwai and makamaka 558

The authors and contributors

DR John Dawson was associate Professor of botany at Victoria university until his retirement in 1988. since then, he has been undertaking botanical research in new caledonia, exploring its botanical links with new Zealand and researching its largest plant family, Myrtaceae. he has formally described about a quarter of the c. 250 species of Myrtaceae in new caledonia, has published two accounts of these and completed a third. John also runs extension courses on new Zealand native plants and guides groups around otari native botanic Garden in wellington. he is the author of many

papers on aspects of new Zealand flora, in particular the apiaceae, and several books, including Forest Vines to Snow Tussocks: The story of New Zealand plants (1988) and Seasons in the Forest (with photographs by brian enting, 1990)

Rob Lucas lectured in horticulture at The open Polytechnic of new Zealand until his retirement in 2006. he has been photograph-ing plants for several decades, and his photographs have been widely published in books and magazines. he is the author of Managing Pests and Diseases: A handbook for New Zealand gardeners and co-author (with Isobel Gabites) of The Native Garden: Design themes from wild New Zealand (1988).

John Dawson and Rob Lucas are co-authors of the award-winning Nature Guide to the New Zea-land Forest (2000), Lifestyles of New Zealand Forest Plants (1993), Lifestyles of New Zealand Coast and Mountain Plants (1996) and The Nature of Plants: Habitats, challenges and adaptations (2005).

Jane connoR has been Managing Director and Publisher at craig Potton Publishing since 2007. she has many years’ experience editing, designing and publishing books on plants, both in new Zealand and internationally. she co-founded Godwit Press and was later Publishing Direc-tor of Random house new Zealand, before moving to north america, where she was Publisher and executive Vice-President of Timber Press in Portland, oregon.

DR PaTRIcK bRownsey is a leading authority on the ferns of new Zealand, australia and the Pacific. he is a Research Fellow at the Museum of new Zealand Te Papa Tongarewa in wel-lington, and is currently working with staff at Te Papa and Landcare Research in christchurch to prepare an electronic flora of new Zealand.

shanneL couRTney is a nelson-based plant ecologist, who has worked with the Depart-ment of conservation since 1987, currently specialising in threatened plants. he has an Msc in plant ecology, and botanical survey work in northland, east cape, Taranaki, wellington, nelson, Marlborough, canterbury and on the chatham Islands has provided him with a good working knowledge of regional floras. In 2008, he was the recipient of the Loder cup for his contribution to native plant conservation.

8 9

DR PeTeR De LanGe works as the Threatened Plant scientist for the Department of conserva-tion. based in auckland since 1993, his work includes plant biosystematics, cytology, ethnobotany, threatened plant management, and threat classification systems. a Fellow of the Linnean society (FLs), Peter is the author of 14 books and 120 scientific papers. he has a particular interest in the conservation and documentation of island floras, and he has worked on the Kermadec Islands, the chatham Islands and many of the smaller offshore islands of northern new Zealand.

DR PhIL GaRnocK-Jones is a plant taxonomist and emeritus Professor of botany at Victoria university of wellington. after completing his PhD at the university of canterbury on the tax-onomy of Parahebe (now included in Veronica), he worked for 20 years at botany Division, DsIR. between 1994 and 2009, he was Professor of Plant science at Vuw, and taught botany and evolu-tion. he has published 90 papers, mostly on the taxonomy and phylogeny of new Zealand plants.

DR MaRK LaRGe is a biologist with an interest in fern evolution and paleobotany spanning 30 years. he has authored many publications, including Tree Ferns (2004) with John braggins, and acted as botanical consultant for the popular television series ‘walking with Dinosaurs.’ he is cur-rently working, with Professor Peter Lockhart, on a book on the evolution of new Zealand plants.

DR Don MoRRIsey is a marine biologist with the national Institute of water and atmospheric Research (nIwa) in nelson. his main research interests include benthic ecology, such as the environmental effects of marine farms, and biosecurity. he has published research papers and reviews on the ecology of temperate mangroves, including the ecological implications of man-grove spreads.

DR baRRy sneDDon lectured in botany and managed the h.D. Gordon herbarium at Victoria university of wellington until retiring in 2000. he then worked for seven years as a collection manager at the herbarium of the Museum of new Zealand – Te Papa Tongarewa. his main bo-tanical interests are the seed-plant flora of new Zealand and herbaria.

our forebears’ relentless destruction of large tracts of native forest is something most of us nowa-days deplore. Given our now-comfortable lifestyles, it is easy to have this attitude—particularly when we survey the eroding hills and valleys, rapidly aggrading river beds and silt-filled waterways that this destruction brought about.

new Zealand’s early settlers were fearless forest-fellers—but they had to be. we, too, would have seen the world quite differently if we had been living in a flimsy, hastily cobbled-together hut in the densely forested hutt valley in the mid-nineteenth century. Given their pressing need for shelter and security, is it realistic for us to expect them to have taken a more conservation-minded approach to tree felling and forest destruction? Probably not.

as our living conditions have improved, so too has our relationship with our landscape, in-cluding our native trees and forests. we have belatedly realised that, if we don’t act now, a lot of what we have previously taken for granted will soon vanish—forever. what’s more, we’ve learnt that our native forests must be treated with respect. some of this is driven by the practical need to heal the landscape and improve water quality, but some is less tangible—it’s an acknowledge-ment that what we’ve got is beyond quantifying; it’s bigger than all of its parts and bigger than us, too. belatedly, too, we now realise that what we have is not replicated elsewhere in the world—it is truly unique.

standing tall within many of our landscapes are the native trees, some of which probably date back 80 million years, to the time new Zealand rafted away from australia as the Tasman sea developed. For of all our natural plant communities, it is the forests and their trees which attract the most attention and reverence.

This book profiles all our native trees, from the massive giants to the inconspicuous species that rarely or barely reach tree stature. It is packed with photos and written descriptions that include notes on the ‘bigger picture’—pollination, seed dispersal, insect interactions, traditional uses and the like. we hope that all new Zealanders can open and enjoy our book and that it becomes a favoured reference for all those involved with nurturing and revegetating our landscapes, those who grow them for pleasure or profit and, not least, those who just love our native trees and wish to get to know them better.

During the book’s nearly seven-year gestation period, we have enjoyed the support and en-couragement of many people. we list, with our thanks, many of these below, but we are aware that, inevitably, some names will have been inadvertently missed. If you are one of the missing, please accept our grateful thanks—and apologies.

Jill broom, Patrick brownsey, eleanor burton, Matt calder, Janeen collings, shannel courtney, Mark Davis, Peter de Lange, the late arnold Dench, Rewi elliottt, Pat enright, esme and Don Finch, Lisa Forester, Kerry Gillbank, brian halliday, barry and Jane hart, cathy and Raymond hayter, neil and Irene hayter, Peter heenan, wendy holland, olaf John, James Jones, nicola McDonald, Jenny and David McLaren, Tom Myers, Tim o’Leary, Leon Perrie, wayne Peters, chris and brian Rance, Viv and bruce sampson, Tony silbury, Philip simpson, barry sneddon, adele and sid stewardson, andrea Townsend, Maureen young.

and finally, to our wives: sharon, who after nearly seven years has had the dubious pleasure of discovering that, yes, she still has a husband. (RL); and Judy, who is as relieved as I am that we can now turn our attention to other things (JD).

John Dawson anD Rob Lucas

Authors’ preface and acknowledgements

38 39introduction to conifers introduction to conifers

What is a conifer?

conifer is a Latin word for ‘cone-bearing’ and alludes to cones being the typical reproductive structure of this group of plants. conifers are the largest of the four groups of plants that constitute the gym-nosperms. They are derived from a unique common ancestor in the late Palaeozoic era (300+ million years ago). conifers are separated from the other gymnosperm groups and from the angiosperms by the following shared features:

• scale- or needle-like leaves, or leaf forms that have been derived from them.

• Water- and food-conducting cells that are less specialised than those in flowering plants.

• Pollen grains that either have 2–3 wings (air bladders) or are wingless and nearly spherical; their surface can be granular or smooth, and they mostly contain more than three cells. in comparison, the pollen grains of angiosperms lack wings, vary widely in shape and surface sculpturing, and contain only two or three cells.

• female or seed cones with a unique structure (page 43).

conifers are woody plants and range from the tallest tree in the world, coast redwood (Sequoia sempervirens), at 115 m, to small prostrate shrubs. conifers can also claim the largest tree, giant redwood (Sequoiadendron giganteum), with a maximum volume of 1487 cubic metres; the thickest trunk, Montezuma cypress (Taxo-dium mucronatum), with a diameter of 11.5 m; and the oldest living tree, bristle cone pine (Pinus longaeva) at 4700 years. new Zealand conifers include three very tall trees— kauri (Agathis australis), rimu (Dacrydium cupressinum) and kahikatea (Dacrycarpus dac-rydioides)—all of which can attain a height of 50 m or more; and, at the other extreme, one of the smallest conifers in the world, pygmy pine (Lepidothamnus laxifolius), a dwarf shrub that rarely exceeds 30 cm in height and can produce cones on shoots only 5 cm high. The great majority of conifers, including all new Zealand species, are evergreen.

conifer faMiLies

conifers are found on all of the world’s continents except antarctica. in the northern hemisphere, they extend to the arctic treeline, reaching their latitudinal limit at 73° n in siberia, and in the southern hemi-sphere, they reach almost to the southern tips of africa, tasmania, stewart island and tierra del fuego (chile), where they have their southern limit at 55° s. The 546 species are divided among six families and 67 genera, with the currently recognised families distinguished mainly by differences in cone structure, especially seed-cone structure.

new Zealand’s indigenous conifers are in three families and 10 genera (see table below); there are 20 species, all of which are en-demic. eighteen of these are trees, or can form trees in favourable situations, and two are low shrubs.

new Zealand’s conifers are dominated numerically by the family Podocarpaceae, with 17 (85%) of the 20 species and eight (80%) of the 10 genera belonging to this family. it is mainly a southern hemisphere family, with representatives in australasia (where new Zealand, tasmania and new caledonia, especially, are centres of diversity), southeast asia and southern Japan, central and south america, and sub-saharan africa; there are c. 18 genera and 156 species in the family. among new Zealand’s Pacific neighbours, the islands of new Guinea and fiji have conifer floras similarly dominated

introduction to conifers

neW ZeaLand’s conifers

araucariaceaeAgathis australis kauri

cuPressaceaeLibocedrus bidwillii pahautea, mountain cedarLibocedrus plumosa kawaka, kaikawaka

PodocarPaceaeDacrycarpus dacrydioides kahikatea, white pineDacrydium cupressinum rimu, red pineHalocarpus bidwillii bog pineHalocarpus biformis pink pineHalocarpus kirkii monoaoLepidothamnus intermedius yellow-silver pineLepidothamnus laxifolius pygmy pine (shrub)Manoao colensoi silver pine, manoaoPhyllocladus alpinus mountain toatoaPhyllocladus toatoa toatoaPhyllocladus trichomanoides tanekahaPodocarpus acutifolius needle-leaved tōtaraPodocarpus cunninghamii mountain tōtara, thin-barked tōtara Podocarpus nivalis snow tōtara (shrub)Podocarpus totara var. totara tōtara, lowland tōtara var. waihoensisPrumnopitys ferruginea miro Prumnopitys taxifolia mātaī, black pine

by this family, whereas australia and new caledonia both have many species (in six and eight genera, respectively) of Podocarpaceae, but the family constitutes a smaller percentage of their conifer floras.

The cypress family, or cupressaceae, comprises c. 28 genera and 136 species in the northern and southern hemispheres. two spe-cies of Libocedrus are new Zealand’s only members of this family.

The third new Zealand conifer family is araucariaceae, an ancient family now largely restricted to the tropics and subtropics of the southern hemisphere, excluding southern africa. The family was widespread in both hemispheres in the Mesozoic era but disappeared from the northern hemisphere at the time of the extinction of the dinosaurs in the cretaceous. There are three genera—Araucaria, Agathis and the recently discovered Wollemia—and 35 species, ranging from south america to new Zealand, new caledonia, australia and southeast asia. Agathis australis, the kauri, is the only new Zealand representative.

trunk, bark and tiMber

in most conifers, the trunk is cylindrical and tapers distinctly upwards. Large trees of some species, such as kahikatea, can have buttressed and fluted trunks. other conifers, such as kauri, have massive columnar trunks that barely taper throughout their length, which can be up to 30 m in kauri.

The bark of conifer species varies considerably, especially on ma-ture trees. Most species have smooth bark on young trees, varying in colour and surface irregularities such as blisters, bumps, ridges and lenticels. Mature bark may be smooth, or roughened by ridges, furrows and lenticels in a variety of patterns, and by the shedding of strips or irregular-shaped flakes. rimu bark is shed in large, thick flakes, whereas kauri, kahikatea, mātaī and miro have smaller bark flakes that, when shed, leave a ‘hammer-mark’ pattern on the trunk. in some conifers, the bark is papery, peeling away in long (e.g. Libo-cedrus spp.) or short (e.g. hall’s tōtara), vertical strips or sheets; or it can be fibrous–stringy, furrowed and often light brown, as in tōtara, and peeling away from the trunk in long, persistent strips. Many massive conifers, such as kauri, develop a mound around

the base of the trunk resulting mainly from the accumulation of discarded bark flakes.

conifer wood is referred to as softwood and that of flowering trees as hardwood, because of their comparative hardness. however, there are some striking exceptions, such as the softwood yew (Taxus baccata), which has timber nearly as hard as that of the hardwood oak (Quercus robur), and the hardwoods balsa (Ochroma pyramidale) and the new Zealand native whau (Entelea arborescens, page 266), whose timbers are both softer and lighter than any conifer woods. softwoods consist of more than 90 percent water-conducting cells or tracheids, and are more uniform and less complicated in structure than hardwoods because they lack the fibres and specialised water-conducting vessels present in most hardwoods.

The conifers most preferred for their timber have wood that is strong, straight-grained, easily worked and naturally durable (or easily made durable by preservative treatment). The most valued native conifer timbers include kauri, tōtara, rimu, mātaī and miro. tōtara and silver pine timbers are exceedingly durable in the ground, with both timbers rated in the highest natural durability category of ‘very durable’ (> 25 years). however, only recycled native timber or fallen trees can be used nowadays.

root systeMs of conifers

conifers usually have a shallow, wide-spreading root system that functions to anchor the tree in the ground, and extract water and nutrients from the soil. often the root system is plate-like, which can be seen in wind-thrown individuals. a taproot may or may not continue to develop beyond the seedling stage; for example, trees of kahikatea and kauri have a taproot, whereas in tanekaha and silver pine, the taproot is weakly developed or absent. taproot depth is limited by low soil-oxygen levels. Lateral roots arising from a seedling’s primary root become the largest roots of the tree. They

1 2 3

1. bark of mature rimu (Dacrydium cupressinum), showing the distinctive ‘contour-map’ pattern of ridges. 2. ‘hammer-marked’, mature bark of mātaī (Prumnopitys ferruginea). 3. bark of mature kawaka (Libocedrus plumosa), which separates in long strips.

40 41introduction to conifers introduction to conifers

taper and branch, and often extend outwards beyond the spread of the mature crown. Those of young trees can be on the surface, but usually they become buried as the trees mature, although mature kahikatea have long, surface laterals on swampy soils. Lateral roots support an extensive network of fine roots and feeding rootlets near the soil surface throughout the entire rooting area. in good soil, most of the feeding roots are in the top 30 cm. Large lateral roots may produce downwardly growing sinker (‘peg’) roots, which give the tree access to water from greater soil depths. rimu can have large sinker roots up to 30 cm in diameter, which descend vertically or obliquely for 1 m or more. The feeding roots of all conifers, like those of most angiosperms, are associated with symbiotic mycor-rhizal fungi that help them to absorb nutrients such as phosphorus (as phosphate ions) from the soil. in return, the trees provide their fungal partners with sugars (glucose and sucrose). The fine roots of all new Zealand Podocarpaceae bear small, swollen growths called nodules, which have been found to contain the mycorrhizal fungi.

forM and GroWth Pattern of conifers

Many conifers are trees with a single trunk and a conical crown; smaller trees and shrubs often have a dome-shaped crown and several stems rather than one trunk. When young, tree conifers often have a regular rhythmical growth pattern: a single trunk produces tiers or whorls of spreading branches at intervals from its apical growing point, and the branches of the older, lower whorls generally become longer and more branched than the younger branches above. This growth pattern produces the conical crown characteristic of conifers. With age, growth of the tree apex usually becomes irregular. some conifers retain a conical crown throughout their life, but in most, the crown broadens to dome- or vase-shaped as the tree matures, and some become flat-topped. The lower whorls of branches are

often shed when their foliage dies, resulting in the clean lofty trunk (bole) below the crown of tall trees.

The main branches of conifer trees vary from more or less horizontal to vertical, with their lateral branches and branchlets often having the same inclination as the parent branch. horizontal branches can be intricately branched in the same plane, which in scale-leaved conifers, such as kawaka, gives the foliage a distinctly frond-like appearance. branchlets (twigs) are the current year’s growth of a branch and bear the youngest leaves. as branchlets age, their leaves (which may persist for many years) die and drop off, while their stems gradually thicken and bark forms. Thus, if they persist, branchlets gradually become branches.

a few conifer genera produce two types of leafy branches called long shoots and short shoots. Long shoots extend the length of the branch, and short shoots are borne laterally on these, have very limited stem extension and contain most of the leaves. in native conifers, this type of branching is seen in the juvenile stage of kahi-katea, where slender, long shoots bear horizontally arranged, short shoots several centimetres long.

Three native conifers can have an unusual form of vegetative growth in which individuals form extensive, multi-trunked patches. bog pine extends outwards by branch layering to form more or less circular patches up to 10 m across. This growth form occurs when lower branches in contact with the ground develop roots and bend upwards at the tip to form new trunks, which in turn produce their own horizontal rooting branches. The patches thus formed may develop a hollow centre resulting from the death and decay of the original trunks. silver pine and mountain toatoa form patches from sucker shoots produced from underground horizontal branches.

needLes, scaLes and other Leaf forMs

The leaves of conifers can be broadly grouped into scale leaves, needle leaves and broader forms, with a variety of intergrading shapes in between. native conifer leaves range in length from 1–2 mm (scale leaves) to 10 cm and in width from c. 1 mm to 15 mm. The longest and widest leaves are those of juvenile kauri.

4 5 6

4. a young ‘ricker’ kauri (Agathis australis), with a narrowly conical crown and whorled lateral branches. 5. a mature kauri, with a tall, columnar trunk and a much-branched crown with branches not tiered. 6. Juvenile mātaī (Prumnopitys taxifolia), with many slender, interlacing, brownish branches and small leaves.

Leaves consist of three parts: the base, which is a cushion-like point of attachment of the leaf to the stem; the blade, which is the green, photosynthetic part of the leaf; and the petiole or stalk, which links the blade to the leaf base and is typically short in conifers. scale leaves are small, short leaves that usually lack a petiole and are pressed against the stem of their branchlet. needle leaves are much longer than scale leaves, narrow, parallel-sided, angular or flattened in cross-section, and mostly pointed at the tip. broad leaves are also much longer than scale leaves, flat in cross-section and often widest at the middle, with curved margins that taper gradually or abruptly towards the base and pointed or rounded tip. scale leaves generally have a single mid-vein, as do needle leaves, and broad leaves have a single mid-vein or numerous parallel veins (as in kauri).

The leaves of most conifers have one or more resin ducts (page 42) along their length, and there is often fibrous tissue present internally, which makes the leaves tough and leathery. sometimes water-storing tissue is also present (e.g. Podocarpus spp.). The stomata (breathing pores) of conifer leaves, which are not visible individually without magnification, may be grouped in whitish, waxy bands or patches on protected leaf surfaces as, for example, in mātaī and Libocedrus spp. conifer leaves can be modified to perform specialised functions other than photosynthesis, for example, they can be reduced to hard, overlapping, protective scales on resting buds (e.g. Podocarpus spp.), or to bracts that support and protect the reproductive structures of seed cones. Leaves of evergreen conifers mostly live for 3–5 years, sometimes much longer.

The genus Phyllocladus, which is represented in new Zealand by three species, is very unusual among the conifers in that its photo-synthetic organs are flattened stem structures called phylloclades. small, green leaves are present on seedlings and ephemerally on the most recent stems of adults; and minute, scale-like, curved, non-functional leaves occur on the margins of the phylloclades. (see page 81 for more detail.)

JuveniLe and aduLt forM and foLiaGe

some indigenous conifers pass through a sometimes prolonged juvenile stage in which the young plant differs in form from the adult. notable examples are kauri, rimu, kahikatea and mātaī. young kauri trees have short-lived branches forming a spire-like crown, which can persist several decades before the spreading crown of

7 8

9 10

11

13

12

14

7. Juvenile kahikatea (Dacrycarpus dacrydioides), showing two kinds of branchlets (long and short shoots) and needle leaves flattened into two rows. 8. Juvenile foliage of monoao (Halocarpus kirkii), with long, narrow needle leaves. 9. adult foliage of yellow-silver pine (Lepidothamnus intermedius), with scale leaves arranged in a tight spiral on the branchlets. 10. foliage and a mature seed cone of snow tōtara (Podocarpus nivalis); the undersides of the leaves show a green mid-vein flanked by white bands rich in stomata (John braggins). 11. Juvenile scale leaves of pahautea (Libocedrus bidwillii), showing the decussate leaf arrangement. 12. Juvenile foliage of kauri, with the leaves attached in opposite pairs; later, leaves are borne singly in a spiral around the branchlets. 13. seedling of mountain toatoa (Phyllocladus alpinus), with long, narrow true leaves (needles) and the first phylloclades, with a white bloom, forming in their axils. 14. resting bud of mountain tōtara (Podocarpus cunninghamii) at the tip of a branchlet; the bud scales (modified leaves) protect the growing tip during winter dormancy.

338 Metrosideros

There is scarcely a New Zealander who could not instantly recognise a flowering pōhutukawa, or the huge flowering canopies of the north-ern and southern rātā trees when they emblazon bush landscapes in summer. These glorious summer sights are indelibly printed into the minds of all New Zealanders. When in flower, pōhutukawa and rātā impart an almost-tropical feel to our often overly cool and temperate landscape.

Pōhutukawa and rātā trees are species of Metrosideros, a genus of c. 50 species of trees, shrubs and woody vines, found in New Zealand and throughout the Pacific. Metrosideros species can also be found in New Caledonia, on Lord Howe island, in the solomons, New Guinea and the Philippines, and as far afield as French Polynesia and Hawai’i.

A recent dNA study of Metrosideros found that the species and varieties in French Polynesia, Hawai’i and other islands are geneti-cally closely related to the New Zealand pōhutukawa, M. excelsa, and have probably evolved from it, following long-distance dispersal from New Zealand. some of the species in these distant places look quite similar to pōhutukawa; others do not. Those that are similar in Hawai’i are notable as early colonisers of lava flows, as is the pōhutukawa on rangitoto island in the Hauraki Gulf.

in accord with the family as a whole, the leaves are gland-dotted, and the showiest parts of the flowers are the many stamens. The flowers are brush-like, mostly bright red or shades of red, sometimes pink, yellow or white, with a single stigma and numerous stamens. trees flower prolifically in season, and the bright-red flower colour attracts birds and also many insects, who feed on the abundant nec-tar produced in the cup-like structures at the centre of the flowers. several species of Metrosideros are important sources of honey in New Zealand.

There are three compartments in the ovaries, and the seed capsules split open into three valves to release the seeds.

All species of Metrosideros are particularly susceptible to browsing by possums, which can eventually kill whole populations.

MetrosiderosPŌHUtUKAWA ANd rĀtĀ

MyrtACeAe

oPPosite: A flamboyant floral statement from an optimistically poised young pōhutukawa, seemingly unfazed by wind, salt and drought, december, Coromandel Peninsula.

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1. shiny, pointed leaves, with a visible network of veins on the underside. 2. A branched inflorescence of small, white flowers, November, Auckland University. 3. A cluster of ripening capsules with persistent calyx lobes, February, Auckland Botanic Gardens. 4. Close view of a trunk of a tree that began life as an epiphyte on a tall tree; the bark is pale grey to white, and soft and spongy, radar Bush. 5. A young tree in cultivation with a short trunk and a tall, wide crown, Auckland University

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Metrosideros bartlettiiBArtLett’s rĀtĀ

First observed in 1975 in radar Bush near Cape reinga at the northern tip of the North island by an Auckland school teacher and amateur botanist, John K. Bartlett, Metrosideros bartlettii was a remarkable discovery. it was not a small plant easy to overlook but a large tree, up to 25 m in height, with trunks 1 m or more in diameter consisting of coalesced roots, . Bartlett noticed it because of its unusual bark, which is almost white, soft and spongy, separating in thin flakes. There were no flowers present, but leaves enabled it to be identified as a Metrosideros.

twenty-seven trees of Bartlett’s rātā are now known growing in bush remnants in valley heads on the te Paki peninsula. They grow mostly near streams or in swampy sites, and they may be terrestrial or initially epiphytic on trees, including pūriri (Vitex lucens, page 552), or tree ferns. Those that are epiphytic on trees are the tallest, standing on pseudotrunks of their coalesced roots.

The leaves are of similar size to those of northern and southern rātā (Metrosideros robusta and M. umbellata), but they are different in other respects: they are thin in texture, narrowed to a point at the tip, with the vein network visible on the underside but no oil glands.

it was not until 1984 that flowers were seen, and they were a fur-ther surprise, being small, white and looking like snow over the tree crowns. The flowers are c. 8 mm long with stamens c. 5 mm long. The capsules are c. 4 × 2.5 mm. Flowering is in late spring to early summer, and seed capsules mature from late summer to early autumn.

The threat status of Metrosideros bartlettii is ‘nationally critical.’

1. Leaves are longer than wide and have a tomentum of white hairs on the underside. 2. A northern seashore with pōhutukawa dominating forest at the edge of the sea, tui Park. 3. A brilliant summer display of flowers, with new leafy shoots emerging, tui Park.

Metrosideros excelsaPŌHUtUKAWA

Pōhutukawa is the best known of the New Zealand species of Me-trosideros, and it could be called the native-tree icon of the northern North island, where it grows naturally. it is also widely planted fur-ther south as a garden and street tree, and has naturalised in many places south of its natural range. referred to as the New Zealand Christmas tree, it provides a brilliant display in late december and January, often as a backdrop to beaches crowded with holiday-makers.

in nature, pōhutukawa ranges from the Three Kings islands, off the northern tip of the North island, to Poverty Bay in the east and northern taranaki in the west. it is a very salt-tolerant tree, and its favoured habitat is along the coast, although it also grows along lake edges in the rotorua district.

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4. A tree with massive spreading branches and aerial roots, Wellington Botanic Garden. 5. Aerial roots like straw brooms with red growing points to the rootlets; these ‘brooms’ generally do not reach the ground, but on sea cliffs they do to anchor the tree. 6. Close view of leaf underside showing the dense tomentum of white hairs. 7. A pioneer, tiny pōhutukawa seedling established in scoria, rangitoto island. 8. Foliage with furry, white buds and opening flowers, January. 9. Fully open flowers; the yellow tips to the stamens are the pollen-containing anthers, december. 10. Fully open yellow flowers, a rare colour form, december, cultivation, Birkenhead.11. Mature capsules opening to reveal the many thread-like seeds, cultivation, May, Hutt valley. 12. Pōhutukawa forest on rangitoto island, with astelias growing underneath and a plant of the normally epiphytic puka (Griselinia lucida, page 274).

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old trees are often wider (up to 40 m) than they are tall (15– 20 m), a result of their diverging branching pattern. The trunks are often short and can be 1–2 m in diameter, branching into many massive secondary trunks, which are inclined or sometimes hori-zontal. The bark is similar to that of northern rātā (Metrosideros robusta)—grey-brown, rough and separating in thick flakes.

Woody aerial roots can be abundantly produced. Those that hang from spreading branches look like straw brooms; those that develop from the trunk generally grow down to the ground, serving to partly anchor trees on cliffs.

The leaves of pōhutukawa are thick, dark glossy green, 5–10 × 2.5–3 cm, with pointed to rounded tips and a dense furry tomentum of whitish hairs on the underside, except on young plants. The twigs and flowers are also furry, which confers drought- and salt-spray tolerance.

The flowers are c. 3.5 cm long, with stamens c. 2.5 cm long, usually bright red but sometimes yellow, pink or white. Flowers produce abundant nectar, which attracts bird and lizard (gecko) pollinators. The fallen stamens can colour the ground red for a

time, and the pavement beneath flowering streetside trees can be liberally spattered with nectar. The seed capsules are c. 7 × 6 mm. Flowering is from early to mid-summer, with capsules maturing from mid-summer into autumn.

Along with northern rātā, pōhutukawa has colonised the lava of rangitoto island in the Hauraki Gulf, following its eruption a few centuries ago. The two species have hybridised there, and also in Northland, to provide a range of intermediate forms.

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1. The leaves are short and broad, with white, hairy undersides. 2. A tree in cultivation, with a short trunk or trunks and a broad, rounded crown, June, Hutt valley. 3. rough, brown bark. 4. Flower buds with bright-red petals and white, furry ovaries sit above young fruits, september. 5. ripe capsules releasing seeds (left), and flower buds and flowers (right), May.

Metrosideros kermadecensisThe kermadec pōhutukawa only occurs naturally on raoul island, where it is the dominant forest tree. Like its relative the mainland pōhutukawa, it is widely planted throughout the warmer, par-ticularly coastal areas of the North island, where frosts are absent or slight. Unlike the mainland pōhutukawa, it does not present a summer floral display where the canopy is aglow with flowers. The Kermadec pōhutukawa flowers sporadically throughout the year, with the heaviest flowering often occurring in the winter months.

trees are up to 15 m tall, usually multi-trunked from the base, and have grey, flaking bark. Leaves are smaller than those of Metrosideros excelsa, 2–5 cm × 1–3 cm, widest at the middle and tapering to a blunt tip, with recurved margins. The leaf underside, buds and young stems are covered in a white tomentum, which later becomes grey.The flowers are crimson, with tiny red petals and numerous showy, red stamens on filaments 1.5–2.0 cm long. The persistent woody capsules, which occur throughout the year, have three compart-ments that, when ripe, are packed with numerous tiny, slender seeds.

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1. The leaves are hairless, with short stalks and round bases. 2. Leaves in pairs and a developing shoot at the tip. 3. A shrub with flower clusters, Percy scenic reserve, Lower Hutt. 4. A cluster of bright-red flowers with long stamens, october. 5. inflorescences with opening flower buds and young capsules; note the very long styles, october. The inflorescences of this species arise below the leaves on the woody branches. 6. Mature and immature seed capsules, November.

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Metrosideros parkinsoniiThis species has an unusual distribution, being most common in the northwest south island, from Collingwood to just south of the Paparoa range, in coastal to mountain forests. it is also in the upland forests on Great and Little Barrier islands off the eastern Northland coast. in forest and in cultivation, it is a straggling shrub, although the flowers are very striking. in open habitats, it becomes a small tree, up to 7 m tall, multi-trunked and tortuous, with trunks up to 4 cm in diameter and rough bark.

The branchlets are square in section, and the leaves are thick, 3.5–5 × 1.5–2 cm, narrowing to a point. There is almost no stalk, with opposite leaves of each pair clasping the stem. Leaves are of-ten blistered, caused by scale-insect damage, and there is often red discoloration on the leaves.

The branched inflorescences are borne on woody stems below the leaves. The flowers are bright crimson, 6–9 mm in diameter, with unusually long stamens, up 25 mm. The capsules are 6–7 mm long with strongly developed veins. Flowering is from late spring to mid-summer, fruiting in autumn.

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1. Leaves have oil glands (not visible here) and a small notch at the tip. 2. Leaf tip with a small notch and prominent vein network. 3. A branch with flowers in front of rough bark separating in strips, december, Hutt valley. 4. A mature, freestanding northern rātā with a trunk of coalesced roots; the original supporting tree has long since rotted away, Kaitoke regional Park. 5. The original tree in this remarkable combination was a rimu and what remains of its crown is lowermost. At the top is the flowering crown of a northern rātā, which established as a shrub in the rimu crown and now has massive roots descending to the ground. immediately below the rātā is the smaller crown of a puka, with big, shiny leaves and a root descending to the ground. There are masses of nest epiphytes to the right of the puka—truly a garden in the treetops, January, Kaitoke regional Park. 6. early stage of northern rātā on a rimu; the main descending root is on the right, with more or less horizontal girdling roots. 7. A tree crown in full flower; the dead, twiggy branches may be the result of possum damage, december, Hutt valley.

Metrosideros robustaNortHerN rĀtĀ

one of New Zealand’s forest giants, northern rātā can be common in lower-altitude conifer–broadleaf forests throughout the North island and in the northwest of the south island as far south as Hokitika. Like the puka (Griselinia lucida, page 274), northern rātā is a specialised woody epiphyte that eventually sends a root or roots to the ground. in this case, however, the descending roots become very massive and fuse together to form a pseudotrunk, up to several metres in diameter. This supports the northern rātā crown after the supporting tree has died and rotted away, so the rātā can end up being taller than its host, at up to 30 m or more.

A number of tree species serve as supports for northern rātā. Among conifers, the rimu is notable, also kahikatea and miro. Flowering trees include pukatea and pūriri, and it probably also grows on others of its species, although this would be difficult to determine. it has been noted that northern rātā establishes only on fully mature trees whose crowns are in good light.

The small, thread-like seeds of northern rātā are blown into tree crowns by strong winds. The best places for them to germinate and establish are in branch forks and on inclined branches, where a mod-est amount of soil has been built up by mosses, lichens and small epiphytes. After a decade or two, the seedlings become small shrubs. eventually, a string-like root a few millimetres in diameter descends to the ground, close to the tree trunk, branching a few times on the

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8. Close view of a cluster of flowers, december, Hutt valley. 9. seed capsules, with their three valves opening to release the thread-like seeds, April, Hutt valley.

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way. Further up, the rātā is firmly anchored by horizontal girdling roots, which encircle the tree trunk many times. The descending rātā roots gradually become massive, and its crown enlarges and stands above the crown of the supporting tree. When the latter dies, it leaves a central cavity, or ‘treehouse’, among the rātā roots.

Northern rātā has been called the ‘strangling rātā’, implying that it kills the supporting tree. However, as it establishes only on mature trees, these will be very old when the rātā itself is mature, but it is likely that their lives will be at least shortened as a result of root competition and the shading of their crowns.

Northern rātā can also establish on the ground in sunny, open sites, including the scoria of rangitoto island. The trees here are much shorter, at 10–15 m. Their trunks are generally short and up to 1 m in diameter, with many spreading branches. in the northwest of the south island, northern rātā can also establish on limestone outcrops, which provide a surrogate ‘host’. Their trunks are normal, not coalesced, roots, and they can reach 30 m or more in height.

The bark is dark brown and rough, splitting longitudinally into thick flakes. The trunks of fused roots of epiphytic northern rātā can be much wider, up to 2 m or more.

The twigs are four-angled and somewhat hairy. The leaves, in opposite pairs, are smooth-margined and 2.5–5 × 1.5–2 cm, usu-ally with a small notch at the leaf tip. The complete vein network is visible on the underside of the blade, but oil glands are not visible.

The flowers are up to 12 mm long, with many bright, russet-red stamens c. 3 cm long. The seed capsules are c. 6 × 4 mm and split

open to release many thread-like seeds. Flowering is from late spring to mid-summer, with capsules maturing from mid-summer into autumn. in full flower, northern rātā can be a striking sight, the whole crown appearing to be completely red.

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Metrosideros umbellatasoUtHerN rĀtĀ

southern rātā tolerates cooler climates than northern rātā (Metro-sideros robusta). in the south island, it grows in the northwest and in the Marlborough sounds–eastern Nelson. it is abundant on the western side of the island down to Fiordland, and along the south and southeastern (Catlins) coast. it is less common at scattered sites east of the divide in otago and Canterbury. it is an impor-tant component of stewart island forests and on the subantarctic Auckland islands, where it forms a low, dense coastal forest with contorted, sometimes prostrate branches. in the North island, it is present from te Paki south to Mt Manuoha in the Urewera range; it is most common on Great Barrier island and the Coromandel Peninsula. in the southern North island, it also occurs sporadically in the tararua range.

Unlike northern rātā, this species usually establishes on the ground where there is initially good light, such as on steep mountain slopes, ridge crests and riversides. Less often, it grows as an epiphyte with roots descending to the ground and, like northern rātā, it can stand independently after the death of the supporting tree—mostly mountain cedar (Libocedrus bidwillii, page 74).

southern rātā trees are up to 15 m tall. The trunk can be up to 1 m or more in diameter, or much more in very wet Westland habitats, where descending aerial roots arise from the trunk and become fused to it. The bark is papery and separates in thin, narrow strips. At higher altitudes and other exposed sites on thin soils, plants can be stunted to under a metre in height, but they are still able to flower.

1. Note the pointed tips on the leaves; no veins except the midrib are visible on the underside. 2. Close view of leaf underside showing conspicuous oil glands and the midrib as the only visible vein. 3. A mountainside beginning to colour red with southern rātā flowers in summer, January, otira valley.

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4. An emergent southern rātā crown in full flower, January, otira Gorge. 5. Thin-crowned, spindly trees develop on infertile, skeletal soils, February, Mt rochfort. 6. Windswept southern rātā canopy in flower in the Auckland islands; the other shrubs with bright-green foliage are Myrsine divaricata (page 362), January, enderby island. 7. A display of bright-red flowers and pointed leaves; the yellow cups in the flowers contain nectar, January, enderby island. 8. Bright-red flower buds and one opening flower; note the pointed leaf tips. 9. Fissured bark with a leafy shoot. 10. Close view of seed capsules splitting open to release the slender seeds, February, Westport.

The leaves, at 3–5 × 1.5–2 cm, are similar in size to those of northern rātā but are easily distinguished. They narrow to a distinct point at the tip, and on the underside there is no vein network vis-ible in fresh leaves; instead, there are conspicuous spots formed by oil glands. young leaves are often bright red. The leaves are sweetly aromatic when crushed. The volatile oils are the reason southern rātā is highly flammable.

The flowers, at c. 2.5 cm long, with stamens c. 2 cm long, are larger than those of northern rātā and bright red, although there are occasional trees with yellow flowers. The seed capsules too are larger, c. 8 × 8 mm, and quite hard. They take a year to mature and release their seeds. Flowering is from late spring to mid-summer, and the capsules open in the summer of the following year. in a good flowering year, southern rātā on south island mountainsides are completely red—perhaps the most spectacular of all the rātā.

sadly, possums have wiped out southern rātā from large areas of the West Coast where they are not controlled.

southern rātā has some of the hardest, densest wood in the world. Honey derived from Metrosideros umbellata is said to be one of the finest in the world; it is light in colour, with a distinctive, almost salty flavour.

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