Flora and Vegetation of the Cavalli Islands (Except Motukawanui), Northern New Zealand

Home , Arthropodium cirratum, Asplenium flaccidum, Dichelachne

TANK 25, 1979

FLORA AND VEGETATION OF THE CAVALLI ISLANDS (EXCEPT MOTUKAWANUI), NORTHERN NEW ZEALAND

by A.E. Wright Department of Botany, University of Auckland, Private Bag, Auckland

SUMMARY

A combined flora of 242 taxa of higher plants is presented for 28 vegetated islands (excepting Motukawanui, the largest island) in the Cavalli Island Group. The islands range from small wind- and sea-swept rock stacks to 38 hectare Motukawanui (Step Island) which is farmed. Analysis of the combined flora indicates a high proportion (46%) of adventive plants, due largely to unstable soil conditions and interference with the vegetation by man. A large number of taxa (30%) are confined to one island only, giving evidence of the wide variety of habitats and vegetation com• munities to be found. A brief vegetation description and individual checklists of plants are given for each island and group of rock stacks visited. Unusual plant com• munities and those of largely indigenous composition are treated in more detail. The rare native plant Hibiscus trionum is noted from three islands, on one of which many thousands of plants occur. Finally, a number of general observations on the vegetation of the islands are discussed, and priorities for management and reservation on botanical grounds are given.

INTRODUCTION

The Cavalli Island Group (latitude 35° 00'S, longitude 173° 57'E) lies between two and seven kilometres off the Northland coast and about 16 kilometres east of the entrance to Whangaroa Harbour (Fig. 1). Some thirty vegetated islands and groups of rocks lie scattered around Motukawanui, the largest island, and are geographically divisible into four main groups. The "northern group" include Horonui, Motutapere, Hamaruru, Panaki, Haraweka, Tuturuowai, Nukutaunga and Motutakupu (see fig. 1, Hayward 1979), and for the most part are clothed in a range of communities from grassland through coastal scrub to small areas of developing coastal forest. The "eastern group" of islands are the smallest in number, comprising Motuharakeke, Te Anaputa and the Te Anaputaiti rocks. Vegetation is less disturbed than on any other of the island groups, and Motuharakeke in par• ticular has a lush cover of relatively impenetrable petrel scrub. Remnant forest trees, however, suggest that this cover may not be original.

61 Horonui Is Tuturuowai Is

Nukutaunga Is

(p Motutakupu Is Haraweka Is

North Twin Is &-»- South Twin Is

Te Anaputaiti Rocks on 0° o» O-^-Te Anaputaiti

Te Anaputa Is (P Motu harakeke Is

Motukaroro

Motukeokeo Motumuka

q Tarawera Is

Whatupukeiti Rocks „o

0 --Whatupukeiti Is Whatupuke IsC^j Piraunui Is Algal Rocks / Kahangaro Is

Motukahakaha Is Motukawaiti Is (Step Is)

Kahangaroiti Rc .

Motuhuia Is

Fig. 1. Location of the islands mentioned in the text. Inset shows location of the Cavalli Group off the North Island of New Zealand.

62 The "southern group" are scattered around Motukawaiti or Step Island, the second largest island of the Cavalli Group. They include Piraunui, Motukahakaha, Kahangaro, Tarawera, Whatapuke and Motuhuia Islands, and Whatapukeiti, Kahangaroiti and Algal Rocks. Motukawaiti is presently farmed and is largely clothed in improved pastures. Kahangaro and Whatapuke have been grazed in the past and are now covered in tall grasses with spreading areas of fern and scrub. The remainder, depending on size and exposure have communities of coastal scrub, gorse (Ulex europaeus) and highly salt-tolerant plants. The fourth group consists of those islands lying around the coast of Motukawanui. Apart from Kaitirehe Rock, some hundreds of metres west of Motukawanui, these generally small islands are either accessible from Motukawanui at low tide or separated by small stretches of sea. Moving clockwise from the northern tip of Motukawanui, they include North and South Twins, Te Toi, Moturahurahu, Motukaroro, Motukeokeo and Motumuka down the east coast, and Te Karo and Motumahanga on the west coast. The shelter provided by Motukawanui generally results in con• siderably more diversity of flora than that found on many much larger islands in the northern, eastern and southern groups. Studies on the vegetation of the Cavalli Islands were carried out during the Offshore Island Research Group's scientific expedition from 28 December, 1978 to 7 January, 1979. The higher plants of Motukawanui, the largest island in the group (and the basecamp for the expedition) are described by Court (in prep.) and Wright (1979). This paper examines the higher plant floras and vegetation of the remaining islands, islets and rock stacks in the group. The lichen flora of the whole group is described by Hayward and Hayward (1979).

PREVIOUS WORK

No published account of the vegetation or flora of the Cavalli Islands has been found. While fairly detailed unpublished reports on the botany of Motukawanui Island exist (Dickson 1973, Olsen 1976) only the brief unpub• lished results of a full survey of the Cavalli Islands by the Wildlife Branch of the Department of Internal Affairs (Adams 1969) have been found for the smaller islands. Despite the lack of published material, botanists and naturalists have visited the islands from time to time. A.T. Pycroft visited the islands in January 1932, depositing specimens of some of the more common plants in the Herbarium of the Auckland Institute and Museum (AK). A specimen of Chionochloa bromoides in the Herbarium of the National Museum, Well• ington (WELT) was collected by W.R.B. Oliver from the Cavalli Islands on 23 February, 1934. A.B. Stephenson collected 11 sheets of plants from Motuharakeke Island on 17 May, 1967, and G.P. Adams collected several specimens during his Wildlife Survey from 17-24 October, 1969 (Adams 63 1969). The specimens of both these collectors are deposited in AK.

COMBINED FLORA

242 taxa of native, planted and adventive vascular plants are listed for the islands of the Cavalli Group except Motukawanui (see Wright (1979) for a species list for this island). An indication of each taxon's distribution within the group is given as the number of islands on which the species occurs out of the 28 surveyed. Common names are given in the combined list, but not in the individual checklists for islands which follow, and where applicable follow the New Zealand Weed and Pest Control Society (1969). Families are ordered according to Allan (1961) and Moore and Edgar (1970), except for families not native to New Zealand which are listed alphabetically at the end of each section of the flora. Genera are listed alphabetically within families, as are species within genera.

* indicates species which are not native to New Zealand. ** indicates families which are not native to New Zealand, t indicates species which have been planted.

FILICOPSIDA Dicksoniaceae Dicksonia squarrosa 1 wheki Cyatheaceae Cyathea dealbata 1 ponga C. medullaris 2 mamaku Polypodiaceae Phymatodes diversifolium 10 hound's tongue Pyrrosia serpens 11 Pteridaceae Paesia scaberula 2 scented fern Pteridium aquilinum var. esculentum 14 bracken Pteris comans 3 P. tremula 1 turawera Aspleniaceae Asplenium flaccidum subsp. haurakiense 19 makawe A. lucidum 12 shining spleenwort A. obtusatum subsp. northlandicum 1 Blechnaceae Blechnum capense 4 kiokio B. lanceolatum 1 Doodia media 12 Dryopteridaceae Polystichum richardii 3 Adiantiaceae Adiantum aethiopicum 1 makaka A. cunninghamii 2 maidenhair A. hispidulum 11 rosy maidenhair Cheilanthes sieberi 3 Pellaea falcata 2 SPERMATOPSIDA GYMNOSPERMAE Podocarpaceae Podocarpus totara 6 totara Araucariaceae Araucaria excelsa*^ 1 Norfolk pine Cupressaceae Cupressus macrocarpa*^ 1 macrocarpa Pinaceae Pinus radiata**) 1 radiata pine ANGIOSPERMAE : DICOTYLEDONES Ranunculaceae Ranunculus parviflorus* 1 small-flowered buttercup Piperaceae Macropiper excelsum 4 kawakawa Peperomia urvilleana 4 Cruciferae Brassica oleracea* 1 wild cabbage Cakile maritima* 4 sea rocket Coronopus didymus* 2 twin cress Raphanus raphanistrum* 4 wild radish R. sativus* 3 radish Violaceae Hymenanthera novae-zelandiae 12 Melicytus ramiflorus 11 mahoe Crassulaceae Crassula decumbens* 1 Cape crassula Aizoaceae Disphyma australe 28 NZ iceplant Tetragonia trigyna 15 NZ spinach Caryophyllaceae Cerastium glomeratum* 3 annual mouse-ear chickweed Polycarpon tetraphyllum * 18 allseed Sagina apetala* 8 annual pearlwort S. procumbens* 2 pearlwort Silene gallica * 13 catchfly Spergularia marginata 12 spurrey Stellaria media* 6 chickweed S, parviflora 1 Polygonaceae Muehlenbeckia complexa 22 wirevine Rumex acetosella* 1 sheep's sorrel R. brownii* 1 hooked dock R. conglomeratus* 2 clustered dock R. crispus* 3 fiddle dock Chenopodiaceae A triplex has lata* 2 orache Chenopodium ambrosioides* 1 Mexican tea Rhagodia triandra 6 Salicornia australis 22 glasswort Salsola kali* 2 saltwort Geraniaceae Geranium dissectum* 2 cut-leaved geranium G. homeanum* 1 G. molle* 1 dove's foot G. retrorsum* 3 turnip-rooted geranium G. sp. (unnamed) 10 Pelargonium inodorum 1 kopata Oxalidaceae Oxalis corniculata 10 oxalis Linaceae Linum trigynum* 3 yellow flax Haloragaceae Haloragis erecta 9 shrubby haloragis H. incana 1 Onagraceae Epilobium rotundifolium 1 Callitrichaceae Callitriche stagnalis 1 starwort Thymelaeaceae Pimelea prostrata 15 Strathmore weed Proteaceae Hakea sericea* 2 prickly hakea Coriariaceae Coriaria arborea 3 tutu Pittosporaceae Pittosporum crassifolium 10 karo Cucurbitaceae Sicyos angulata 1 mawhai Myrtaceae Leptospermum scoparium 8 manuka Metrosideros excelsa 22 pohutukawa Malvaceae Hibiscus trionum 3 Hoheria populnea 1 lacebark Lagunaria patersonii*^ 1 Malva parviflora* 1 small-flowered mallow 65 Modiola caroliniana* 4 creeping mallow Euphorbiaceae Euphorbia pep/us* 3 milkweed Rosaceae Acaena novae-zelandiae 1 piripiri Rubus fruticosus agg.* 3 blackberry Papilionaceae Carmichaelia aligera 9 NZ broom Lotus angustissimus* 9 L. corniculatus* 1 L. pedunculatus* 1 lotus major L. subbiflorus* 6 lotus hispidus Medicago lupulina * 1 black medick M. polymorpha* 7 bur medick Melilotus indica * 7 King Island melilot Poly gala myrtifolia* sweet pea shrub Trifolium dubium* 14 suckling clover T. glomeratum* 7 clustered clover T. repens* 1 white clover Ulex europaeus* 4 gorse Moraceae Ficus elastica*^ 1 rubber tree Paratrophis banksii 4 large-leaved milk tree Urticaceae Parietaria debilis 6 NZ pellitory Corynocarpaceae Corynocarpus laevigatus 3 karaka Rhamnaceae Pomaderris phylicifolia var. ericifolia 3 tauhinu Rutaceae Melicope ternata 5 wharangi Araliaceae Pseudopanax lessonii 18 houpara Umbelliferae Apium australe 3 NZ celery Centella uniflora 11 centella Daucus carota* 1 wild carrot Foeniculum vulgare* 1 fennel Hydrocotyle elongata 1 Epacridaceae Cyathodes fasciculata 9 mingimingi C. fraseri 18 patotara Sapotaceae Planchonella novo-zelandica 2 tawapou Myrsinaceae Myrsine australis 2 mapou Loganiaceae Geniostoma ligustrifolium 9 hangehange Apocynaceae Nerium oleander*^ 1 oleander Parsonsia heterophylla 2 kaiwhiria Rubiaceae Coprosma macrocarpa 12 coastal karamu C. propinqua x repens 1 C. neglecta Cheesem. C. repens 28 taupata Galium parisiense* 1 slender bedstraw Compositae Brachyglottis repanda 1 rangiora Carduus pycnocephalus* 1 slender winged thistle Cassinia retorta 13 dune tauhinu Cirsium vulgare* 3 Scotch thistle Crepis capillaris* 12 hawksbeard Erigeron floribundus* 14 broad-leaved fleabane Eupatorium adenophorum* 3 Mexican devil E. riparium* 2 mist flower Gnaphalium audax 1 creeping cudweed G. Claviceps* 1 G. gymnocephalum* 6 creeping cudweed G. involucratum 1 creeping cudweed G. luteo-album agg. 10 Jersey cudweed G. simplicicaule* 2 G. sphaericum* 1 Japanese cudweed 66 G. spicatum* 6 purple cudweed Hypochoeris radicata * IX catsear Senecio bipinnatisectus* 1 S. lautus 25 shore groundsel Siegesbeckia orientalis 1 Silybum marianum* 1 variegated thistle Sonchus oleraceus* If, sowthistle Gentianaceae Centaurium erythraea* 15 centaury Primulaceae Anagallis arvensis * 18 scarlet pimpernel Samolus repens 21 Plantaginaceae Plantago hirtella* 1 swamp plantain P. lanceolata* 7 narrow-leaved plantain P. major* 1 plantain Campanulaceae Wahlenbergia gracilis 8 NZ harebell Lobeliaceae Lobelia anceps X shore lobelia Solanaceae Physalis peruviana* 1 Cape gooseberry Solanum aviculare 1 poroporo S. nigrum* 12 black nightshade S. nodiflorum 4 small-flowered night• shade S. sodomeum* 3 apple of Sodom Convolvulaceae Calystegia sepium 3 greater bindweed C. soldanella 2 shore bindweed C. tugoriorum 9 Dichondra repens 17 Mercury Bay weed Scrophulariaceae Hebe stricta var. stricta 3 koromiko Parentucellia viscosa* 4 tarweed Veronica arvensis* 1 field speedwell Gesneriaceae Rhabdothamnus solandri 2 waiuatua Myoporaceae Myoporum laetum 3 ngaio Verbenaceae Verbena litoralis* 2 blue vervain Labiatae Prunella vulgaris* 1 selfheal Orobanchaceae * * Orobanche minor* 9 broom rape Phytolaccaceae** Phytolacca octandra* 6 inkweed

MONOCOTYLEDONES Liliaceae Allium vineale* 1 wild onion Arthropodium cirratum 19 renga lily Astelia banksii 17 wharawhara A. solandri 3 kahakaha Collospermum hastatum 1 kokaha Yucca sp. *t 1 Agavaceae Cordyline australis 8 cabbage tree Phormium tenax 20 NZ flax Juncaceae Juncus bufonius* 1 toad rush J. gregiflorus 3 rush J. planifolius 1 Luzula picta var. picta 1 Restionaceae Leptocarpus similis 2 jointed rush Palmae Rhopalostylis sapida 1 nikau Orchidaceae Microtis unifolia 1 Thelymitra longifolia 10 sun orchid Cyperaceae Carex breviculmis 9 C. flagellifera 10 C. lambertiana 3 C. pumila 3 sand sedge C. spinirostris 1 C. testacea 1 1 C. virgata 1 Cyperus ustulatus 7 Gahnia lacera 3 Scirpus cernuus 2 S. chlorostachyus 1 S. nodosus 23 Gramineae Agropyron kirkii 13 Agrostis tenuis* 1 browntop Aira caryophyllea* 14 silvery hair grass A. multiculmis* 14 Anthoxanthum odoratum* 16 sweet vernal A vena fatua* 19 wild oat Bothriochloa macra* 7 red-leg grass Briza minor* 15 shivery grass Bromus diandrus* 1 rigput brome B. mollis* 17 B. unioloides* 9 prairie grass Catapodium rigidum* 5 hard grass Chionochloa bromoides 24 Cortaderia splendens 7 coastal toetoe Cynodon dactylon* 5 Indian doab Dactylis glomerata* 12 cocksfoot Deyeuxia billardieri 15 sand wind grass Dichelachne crinita 15 long-hair plume grass D. micrantha 3 short-hair plume grass Festuca arundinacea* 2 tall fescue Holcus lanatus* 7 Yorkshire fog Hordeum murinum* 4 barley grass Lachnagrostis filiformis 10 NZ wind grass Lagurus ovatus* 4 harestail Lolium perenne* 1 perennial ryegrass Microlaena stipoides II meadow rice grass Notodanthonia biannularis 17 danthonia N. racemosa 10 danthonia N. unarede 11 danthonia Oplismenus imbecillis 6 Parapholis incurva* 14 sickle grass P. strigosa* ] Paspalum dilatatum* 14 paspalum P. paspalodes* 1 mercer grass P. scrobiculatum 6 Pennisetum clandestinum* 1 kikuyu Phalaris minor* 2 Poa anceps 14 P. annua* 2 P. seticulmis 7 Polypogon monspeliensis * 1 beard grass Spinifex hirsutus 2 silvery sand grass Sporobolus africanus* 17 ratstail Stenotaphrum secundatum* 2 buffalo grass Stipa teretifolia 1 Vulpia bromoides* 17 vulpia hair grass 68 Musaceae** Musa paradisiaca subsp. sapientum*t 1 banana

ANALYSIS OF THE FLORA

In combining the floras of the lesser islands of the Cavalli Group several unusual and interesting factors have emerged. Foremost amongst these is the very high proportion of adventive plants in the flora. 46% of all taxa are not native to New Zealand, and if ferns (almost always an entirely native group) are discounted, over half the remaining species are adventive (Table 1). The large adventive element is indicative firstly of the unstable physical environment prevailing on small islands with varying degrees of exposure, and secondly the interference with, and modification of the vegetation by man. In the former case, erosion and coastal slips provide a habitat for the establishment of wind-blown annuals such as cudweeds (Gnaphalium spp.), sowthistle (Sonchus oleraceus) and catsear {Hypochoeris radicata) and wind and bird transported grasses such as hair grasses (Aira spp.), wild oats (Avena fatua) and vulpia hair grass (Vulpia bromoides). In the latter case, activities such as farming, cultivation, firing for muttonbirding and temp• orary camping all promote the establishment of adventive shrubs and weeds.

Table I. Distribution of the vascular flora of the lesser Cavalli Islands according to plants groups and native or adventive status.

1 Plant Group Native Adventive TOTALS

Ferns 21 . 21 Gymnosperms 1 3 3 Dicotyledons 65 77 142 Monocotyledons 42 33 75

TOTALS 129 113 242

The second prominent factor to emerge is the manner in which the various taxa are distributed on the islands surveyed. 30% of the taxa are found on only one island while 66% of all taxa are found on one quarter or less of the total number of islands for which species lists were made. Table 2 illustrates the small proportion of taxa that are widely distributed amongst the islands. Extraction of the most widely distributed species gives an immediate sum• mary of the ubiquitous, salt-tolerant, rock crevice community. Only the New Zealand iceplant (Disphyma australe) and taupata (Coprosma repens) occurred on all islands studied. The next most commonly occurring plants were the shore groundsel (Senecio lautus, 25 islands), Chionochloa bromoides (24), Scirpus nodosus (23), pohutukawa (Metrosideros excelsa, 22), glasswort (Salicornia australis, 22), Samolus repens (21), N.Z. flax 69 Table 2. Distribution of total flora of 242 taxa according to the number of islands out of the 28 surveyed on which the taxon occurs.

Number of islands Number of taxa % total flora

1 only 74 30

1< 7 162 66 8<14 47 21 15^21 25 10 22<28 8 3

All 28 2 1

(Phormium tenax, 20), Asplenium flaccidum subsp. haurakiense (19) and renga lily (Arthropodium cirratum, 19). It is interesting to note that all of these plants are native. The most widespread adventive plants were wild oats (19 islands), allseed (Polycarpon tetraphyllum, 18), catsear (18), Bromus mollis (17), ratstail (Sporobolus africanus, 17), and vulpia hair grass (17). The coastal influence is still strongly evident in the next most widely distributed native plants, viz. houpara (Pseudopanax ,lessonii, 18 islands), patotara (Cyathodes fraseri, 18), danthonia (Notodanthonia biannularis probably including some N. unarede, 17), Mercury Bay weed (Dichondra repens, 17), wharawhara (Astelia banksii, 17) long-hair plume grass (Dichelachne crinita, 15), N.Z. spinach (Tetragonia trigyna, 15), sand wind grass (Deyeuxia billardieri, 15) and Strathmore weed {Pimelea prostrata, 15). With the addition of the adventive species sowthistle (16 islands), sweet vernal (Anthoxanthum odoratum, 16) and shivery grass (Briza minor, 15) all those plants occurring on three-quarters (i.e. 15) or more of the 28 islands surveyed are listed above.

VEGETATION DESCRIPTIONS AND INDIVIDUAL CHECKLISTS

In this section, a brief vegetation description for each of the islands surveyed is given, followed by a checklist of the vascular plants recorded. Many lists are by no means exhaustive due to the short period of time available for the exploration of some islands. Individual checklists are pro• vided for ease of reference by future field workers, although space restric• tions have of necessity demanded a compact style. Common names, used in the combined flora list, have not been repeated. The plants are grouped alphabetically in a series of broad classes based primarily on form. A casual glance at the representation within these groups often gives a quick sum• mary of the size, vegetation status (e.g. grassland, forest or salt-tolerant herbs) and degree of exposure of the island. The islands surveyed are treated

70 alphabetically. *denotes adventive species.

Algal Rocks This informal name was applied to a group of rock stacks lying off the northern coast of Motukawaiti (Step Island) which displayed a great lux• uriance and diversity of marine algae. Three rocks supported permanent areas of vascular vegetation. All were much more sheltered than, for exam• ple, Tarawera or the Whatapukeiti Rocks, due to their proximity to Motukawaiti. The southern and eastern stacks were joined at low tide. The eastern stack was a steep, vegetation-capped castle sitting atop a prominent wave-cut platform. The southern (and most sheltered) stack had a central basin which supported a dense mat of iceplant, glasswort and low taupata, and a more elevated western section clothed in Chionochloa and Strathmore weed, with a clump of houpara on the highest point. A vascular flora of 21 taxa was recorded. TREES AND SHRUBS GRASSES DICOT HERBS Cassinia retorta Chionochloa bromoides Anagallis arvensis* Coprosma repens Deyeuxia billardieri Dichondra repens Phormium tenax Lachnagrostis filiformis Disphyma australe Pimelea prostrata Parapholis incurva* Gnaphalium luteo-album Pseudopanax lessonii Vulpia bromoides* Salicornia australis LIANE MONOCOT HERB Samolus repens Muehlenbeckia complexa Scirpus nodosus Senecio lautus Sonchus oleraceus* Spergularia marginata Hamaruru Despite separation at high tide by a small stretch of water, the two parts of this island were joined at low tide by a coarse sand bank, and thus the floras are listed jointly. Landings were made on the small beaches along the southern side of the island. The remainder of the coastline was more or less cliffed. In the small bay on the western part of the island a dense grove of N.Z. flax was found immediately above the pebble beach. Behind the flax was a row of windshorn mahoe (Melicytus ramiflorus) shrubs with a groundcover of Doodia media, rosy maidenhair (Adiantum hispidulum), Carex flagellifera and renga lily beneath. Most of the remainder of the western part of the island supported various mixtures of N.Z. flax, Scirpus nodosus and grasses—predominantly meadow rice grass (Microlaena stipoides), paspalum (Paspalum dilatatum) and danthonias (Notodanthonia biannularis, N. racemosa and N. unarede). Although well-trampled paths were common over this part of the island, modification of the vegetation by burning did not appear to have occurred in recent years, and in places the flax groves had become very dense. Stunted grasses and mats of iceplant, Strathmore weed, centella (Centella uniflora), patotara and dune tauhinu (Cassinia retorta) were found along exposed cliff edges.

In contrast, the eastern part of the island exhibited a greater range of vegetation types and species, due to the longer interval since firing of the 71 plant cover. A steep bush-clad valley led up from the eastern end of the beach. The canopy was provided by many 4-5 metre tall pohutukawa, with a dense shrub layer (2-3 metres tall) of karo (Pittosporum crassifolium), kawakawa (Macropiper excelsum) and mahoe beneath. This understorey continued (without the pohutukawa cover) onto the central summit plateau, with myriads of mahoe striplings 40-50mm in diameter at breast height and an average 350mm apart. Occasional large and senescent mahoe, karo and houpara occurred amongst the striplings. The ground was bare except for patches of Doodia in more open places (e.g. around wind-blown trees). Two less steep gullies occurred on the south-eastern corner of the island. Again, the canopy was provided by pohutukawa, with an understorey of mahoe, houpara and karo. A healthy nikau (Rhopalostylis sapida) grew in one of the valleys. Both gullies supported lush ground-covers of N.Z. spinach, Mercury Bay weed and N.Z. pellitory (Parietaria debilis). A vascular flora of 110 taxa was recorded.

FERNS LIANES C. lambertiana Adiantum cunninghamii Calystegia tugoriorum Gahnia lacera A. hispidulum Muehlenbeckia complexa Luzula picta var. picta Asplenium flaccidum GRASSES Scirpus nodosus subsp. haurakiense Agropyron kirkii Thelymitra longifolia A. lucidum Aira caryophyllea* DICOT HERBS Blechnum capense A. multiculmis* Anagallis arvensis * Doodia media Anthoxanthum odoratum* Centaurium erythraea* Phymatodes diversifolium A vena fatua* Centella uniflora Pteridium aquilinum Briza minor* Cirsium vulgare* var. esculentum Bromus mollis* Coronopus didymus* Pyrrosia serpens B. unioloides* Crepis capillaris* TREES AND SHRUBS Chionochloa bromoides Cyathodes fraseri Carmichaelia aligera Cynodon dactylon* Dichondra repens Cassinia retorta Dactylis glomerata * Disphyma australe Coprosma macrocarpa Deyeuxia billardieri Erigeron floribundus* C. repens Dichelachne crinita Eupatorium riparium* C. repens x rhamnoides Festuca arundinacea* Euphorbia peplus* (C. neglecta Cheeseman) Holcus lanatus* Geranium sp. (unnamed) Cordyline australis Microlaena stipoides Gnaphalium luteo-album Cyathodes fasciculata Notodanthonia biannularis G. simplicicaule* Geniostoma ligustrifolium N. racemosa G. spicatum* Hebe stricta var. stricta N. unarede Haloragis erecta Hymenanthera novae- Oplismenus imbecillis Hypochoeris radicata* zelandiae Paspalum dilatatum* Lobelia anceps Leptospermum scoparium P. scrobiculatum Lotus angustissimus* Macropiper excelsum Poa anceps L. subbiflorus* Melicytus ramiflorus P. seticulmis Medicago polymorpha* Metrosideros excelsa Sporobolus africanus* Melilotus indica* Phormium tenax Vulpia bromoides* Modiola caroliniana * Pimelea prostrata MONOCOT HERBS Orobanche minor* Pittosporum crassifolium Arthropodium cirratum Oxalis corniculata Poly gala myrtifolia * Astelia banksii Parietaria debilis Pseudopanax lessonii Carex breviculmis Phytolacca octandra* Plantago lanceolata* Rhopalostylis sapida C. flagellifera

72 Polycarpon tetraphyllum* Senecio lautus Stellaria media* Raphanus raphanistrum* Silene gallica* Tetragonia trigyna Rhagodia triandra Solarium nigrum* Trifolium dubium* Rubus fruticosus* S. nodiflorum T. glomeratum* Samolus repens Sonchus oleraceus* Wahlenbergia gracilis

Haraweka This almost circular dome-shaped island was most notable for the very large populations of the rare native plant Hibiscus trionum found amongst grasses, wire vine (Muehlenbeckia complexa) and low scrub on the northern side of the island. Many hundreds of single-stemmed seedling-sized plants were found. Almost all were topped by a single flower or seed capsule despite their small size, ensuring production of large quantities of seed. Observations on Nukutaunga Island suggest that management may be required if the Hibiscus is to survive on Haraweka. This point is covered in more detail in the discussion section of this paper. The crown of Haraweka was dotted with clumps of mahoe, N.Z. flax, tutu (Coriaria arborea) and N.Z. broom (Carmichaelia aligera). Small patches of grassland remained amongst the predominant community of bracken (Pteridium aquilinum var. esculentum), tauhinu (Pomaderris phylicifolia var. ericifolia) and manuka (Leptospermum scoparium) scrub (Fig. 3 foreground). A small strip of more mature manuka scrub which had escaped the more recent burning off of the vegetation survived on the south-western slopes. Occasional mahoe, hangehange (Geniostoma ligustrifolium) and large-leaved milk tree (Paratrophis banksii) occurred amongst the manuka with the ferns Doodia media and rosy maidenhair on the ground. A flora of 68 taxa was recorded.

FERNS Pomaderris phylicifolia Vulpia bromoides* Adiantum hispidulum var. ericifolia MONOCOT HERBS Asplenium flaccidum LIANES Arthropodium cirratum subsp. haurakiense Calystegia tugoriorum Astelia banksii Doodia media Muehlenbeckia complexa Carex breviculmis Pteridium aquilinum GRASSES Scirpus nodosus var. esculentum Agropyron kirkii Thelymitra longifolia TREES AND SHRUBS Aira caryophyllea* DICOT HERBS Carmichaelia aligera A. multiculmis* Anagallis arvensis* Coprosma macrocarpa Anthoxanthum odoratum* Centaurium erythraea* C. repens A vena fatua* Centella uniflora Coriaria arborea Briza minor* Crepis capillaris* Cyathodes fasciculata Bromus mollis* Cyathodes fraseri Geniostoma ligustrifolium Chionochloa bromoides Dichondra repens Hakea sericea * Cortaderia splendens Disphyma australe Leptospermum scoparium Dichelachne crinita Erigeron floribundus * Melicytus ramiflorus Lachnagrostis filiformis Eupatorium riparium* Metrosideros excelsa Notodanthonia biannularis Geranium dissectum* Paratrophis banksii N. racemosa G. sp. (unnamed) Phormium tenax Paspalum dilatatum* Gnaphalium spicatum* Pimelea prostrata P. scrobiculatum Hibiscus trionum Poly gala myrtifolia* Sporobolus africanus* Hypochoeris radicata* 73 Orobanche minor* Samolus repens Sonchus oleraceus* Phytolacca octandra* Senecio lautus Trifolium dubium* Polycarpon tetraphyllum* Silene gallica* T. glomeratum* Salicornia australis Solanum nigrum*

Horonui A narrow east-west trending island with a razorback ridge joining high points at either end. The badly eroded eastern end of the island supported sparse iceplant, glasswort and spurrey (Spergularia marginata) while the majority of the flora was found on the western knob. The summit of the island was surmounted by a pipe survey marker. The lower areas, clothed in large clumps of Chionochloa, were heavily burrowed. The vegetation was essentially low scrub and herbs with the three tree species represented by very few small individuals. A flora of 28 taxa was recorded.

TREES AND SHRUBS Avena fatua* Centaurium erythraea* Coprosma repens Bromus mollis* Disphyma australe Hymenanthera novae- Chionochloa bromoides Gnaphalium luteo-album zelandiae Cortaderia splendens Hypochoeris radicata* Metrosideros excelsa Deyeuxia billardieri Polycarpon tetraphyllum * Phormium tenax Dichelachne crinita Sagina apetala* Pimelea prostrata Lachnagrostis filiformis Salicornia australis Pittosporum crassifolium MONOCOT HERB Senecio lautus LIANE Scirpus nodosus Sonchus oleraceus * Muehlenbeckia complexa DICOT HERBS Spergularia marginata GRASSES Anagallis arvensis * Trifolium dubium *

Kahangaro (Fig. 2) This island has been considerably modified by cattle grazing and was mainly covered in tall grasses. Paspalum was dominant in damp and flat areas with a wide variety of other grasses in drier parts. Both blackberry (Rubus fruticosus) and Sodom's apple (Solanum sodomeum) were a con• siderable nuisance in the grasslands. An extensive canopy of wild radish (Raphanus sativus) was established on the flat behind the small bay on the south-east side of the island. A remnant of gnarled mahoe scrub remained in the south-east bay also. This bay, with its sandy beach, was the easiest landing point. Sea rocket (Cakile maritima) grew on the upper beach while silvery sand grass (Spinifex hirsutus) and harestail (Lagurus ovatus) had established on the small dune backing the beach. Extensive N.Z. flax groves had developed in some coastal embayments and on steeper slopes. Steep, rocky areas in the west of the island supported large quantities of Sodom's apple and wire vine. One slope on the south• western side of the island was covered by an extensive mat of Calystegia tugoriorum, in full flower at the time of our visit. A flora of 90 species was recorded.

74 FERNS Dactylis glomerata* Crepis capillaris* Blechnum capense Deyeuxia billardieri Cyathodes fraseri Doodia media Dichelachne crinita Dichondra repens Pteridium aquilinum Holcus lanatus* Disphyma australe var. esculentum Hordeum murinum* Erigeron floribundus* Pyrrosia serpens Lagurus ovatus* Geranium dissectum * TREES AND SHRUBS Microlaena stipoides G. sp. (unnamed) Cassinia retorta Notodanthonia biannularis Haloragis erecta Coprosma repens N. racemosa Hypochoeris radicata* Cordyline australe N. unarede Lotus angustissimus* Melicytus ramiflorus Parapholis incurva* Medicago polymorpha * Metrosideros excelsa Paspalum dilatatum* Melilotus indica* Phormium tenax Poa anceps Modiola caroliniana * Pimelea prostrata P. seticulmis Oxalis corniculata Solarium sodomeum* Spinifex hirsutus Plantago lanceolata* Ulex europaeus * Sporobolus africanus * Polycarpon tetraphyllum * LIANES Stenotaphrum secundatum * Raphanus raphanistrum* Calystegia septum Vulpia bromoides* R. sativus* C. tugoriorum MONOCOT HERBS Rubus fruticosus* Muehlenbeckia complexa Allium vineale* Sagina apetala* GRASSES Arthropodium cirratum Samolus repens Agropyron kirkii Astelia banksii Senecio lautus Aira caryophyllea* Carex flagellifera Silene gallica* Solanum nigrum* A. multiculmis* C. pumila S. sodomeum* Anthoxanthum odoratum* Cyperus ustulatus Sonchus oleraceus* A vena fatua* Scirpus nodosus Spergularia marginata Bothriochloa macra * DICOT HERBS Stellaria media* Briza minor* Acaena anserinifolia Anagallis arvensis* Tetragonia trigyna Bromus mollis* Cakile maritima* Trifolium dubium * B. unioloides* Calystegia soldanella Verbena lit oralis* Catapodium rigidum* Centaurium erythraea* Wahlenbergia gracilis Chionochloa bromoides Centella uniflora Cynodon dactylon* Kahangaroiti (Fig. 2) This tiny islet, although joined to Kahangaro by a sand spit at low tide, was more interesting from a botanical point of view as it was inaccessible to the cattle formerly kept on Kahangaro. Along the clifftops on the northern side of the island was a fringe of grasses — Agropyron kirkii, danthonias, red leg grass (Bothriochloa macra), wild oat, sweet vernal and ratstail — with abundant N.Z. harebell (Wahlenbergia gracilis) and patotara among them. Behind the grasses was an impenetrable thicket of wire vine and bracken. Below this thicket the island sloped down to the low, rocky southern coast. The whole of the slope was heavily burrowed by seabirds. A few large mahoe, Hymenanthera and taupata shrubs rose above the scrubby bracken and N.Z. flax bushes inter• spersed with bird tracks. A large colony of wild radish, with stems up to 50mm thick, occurred in the most heavily burrowed area. Ferns were found below N.Z. flax at the margins of the vegetation — Asplenium lucidum, A. flaccidum subsp. haurakiense and Phymatodes diversifolium. Straggling plants of Doodia media, presumably remnants from an earlier grassy vegetation, were found beneath the bracken. Along the south coast, a well- 75 Fig. 2. Panoramic view of the southern islands looking north and north-east from Motukawaiti (Step) Island. Mainland Northland in left background; Flat Island on centre horizon; Motukawanui, the largest of the Cavalli Islands in right background. Key: A — Motukawaiti: B — Kahangaroiti; C — Kahangaro; D — Motukahakaha; V. — Piraunui: F — Whatapuke; G — Whatapukeiti Rocks; H — Tarawera; I — Algal Rocks; in addition two of the islands lying close in shore to Motukawanui are readily identifiable: J — Motumuka: K — Motukeokeo. Photograph: B.W. Hayward. developed maritime rock crevice community had established, along with quantities of hard grass (Catapodium rigidum) and sickle grass (Parapholis incurva). A flora of 65 taxa was recorded.

FERNS Briza minor* DICOT HERBS Asplenium flaccidum Bromus mollis* Anagallis arvensis* subsp. haurakiense H unioloides* Centaurium erythraea * A. lucidum ('Catapodium rigidum * Crassula decumbens * Doodia media Chionochloa bromoides Crepis capillaris* Phymatodes diversifolium Dactylis glomerata * Cyathodes fraseri Pteridium aquilinum Deyeuxia billardieri Dichondra repens var. esculentum Dichelachne crinita Disphyma australe Pyrrosia serpens Holcus lunulas* Erigeron floribundus * TREES AND SHRUBS Hordeum murinum* Medicago polymorpha * Coprosma repens Lachnagrostis filiformis Melilotus indica* Hymenanthera novae-zealandiaeMicrolaena stipoides Polycarpon tetraphyllum* Notodanthonia biannularis Raphanus salivas* Melicytus ramiflorus N. unarede Sagina apetala* Metrosideros excelsa Parapholis incurva * Samolus repens Phormium tenax Paspalum dilatatum * Senecio lautus Podocarpus totara Poa anceps Silene gallica* LIANE Sporobolus africanus * Solatium nigrum* Muehlenbeckia complexa Vulpia bromoides * Sonchus oleraceus GRASSES MONOCOT HERBS Spergularia marginata Agropyron kirkii Arthropodium cirratum Stellaria media* Aira multiculmis* As lei la banksii Tetragonia trigyna Anthoxanthum odoratum * Carex testacea Trifolium dubium* Avena fatua* Cyperus ustulatus Wahlenbergia gracilis Bothriochloa macra* Scirpus nodosus

Kaitirehe A low rock off the western coast of Motukawanui which supported a shag colony. As is obvious from the abbreviated species list, the vegetation was of a very primitive nature. Small amounts of glasswort grew in the lower rock crevices, with healthy plants of spurrey, to 200mm tall, a little higher above sea-level. The rock was capped by a lush N.Z. iceplant mat with occasional low, bird-shorn taupata bushes. The whole of the vegeta• tion was a very dark emerald green, due no doubt to the continuous fer• tilisation by shags.

SHRUB Disphyma australe Spergularia marginata Coprosma repens Salicornia australis DICOT HERBS Senecio lautus

Motuharakeke (Fig. 3) The largest of the eastern island group, Motuharakeke supported a far more natural plant cover than any other island in the Cavalli Group except Motutakupu. The vegetation was extremely similar to that recorded for Moturoa Island by Wright (1977). The island was partially separated into two blocks by a low rocky saddle washed over in high seas. The eastern end of the island consists of a steep rocky dome (Fig. 3). The lower southern slopes were clothed in mats of N.Z. iceplant. The majority of the southern slopes supported fairly dense taupata-Hymenanthera scrub with almost bare ground beneath apart from very occasional allseed plants and occasional clumps of Asplenium flac• cidum subsp. haurakiense around the bases of the bigger shrubs. On the summit was a colony of fairly old ngaio bushes (Myoporum laetum) and areas of shattered rock with scattered wire vine tangles and Agropyron kirkii. The cliffed northern face was dotted with tufts of Chionochloa and wild oat. The larger, western part of the island was steeply cliffed with a gently sloping summit. Petrel scrub (varying mixtures of taupata and Hymenanthera) was the dominant vegetation, mixed with houpara along the southern side of the island. Extremely dense tangles of wire vine occurred throughout the scrub (centre foreground, Fig. 3). The petrel scrub varied in height from approximately 2 metres tall along the exposed summit to 3 to 4 metres tall on the upper southern slopes. Several large pohutukawa trees stood well above the petrel scrub and near the highest point of the island a gnarled old large-leaved milk tree was found in full flower. Apart from 3 species of Solanum and inkweed (Phytolacca octandra) which were found on the ground in canopy openings, the remainder of the flora was confined to the rocky coast. Rhagodia triandra and N.Z. pellitory were found under the margins of petrel scrub, as reported from Moturoa Island by Wright (1977). Phalaris minor was found in small pockets of grasses at the clifftops in the north-eastern corner of the island.

Adams (1969) noted odd karo and mahoe trees, and N.Z. flax in open• ings. Despite searching, none of these species were located in the present survey. Adams (1969) describes open areas on spurs with "dense ground tangles of Muehlenbeckia or scattered clumps of Neopanax "(now Pseudopanax lessonii). It was evident that major development of the vegetation had occurred over the past ten years as spurs were covered in continuous scrub, and the Muehlenbeckia was climbing amongst the shrub species in the present survey. As Adams (1969) comments, the vegetation appeared at first sight to be an unmodified community due to its general lushness and also by com• parison with the grossly modified plant cover of other islands in the group. In my opinion, the presence of the remnant large-leaved milk tree and the maturing petrel scrub community indicated that the plant cover was far from original, although it may have undergone its last modification earlier than most islands in the group. A flora of 29 taxa was recorded, a small flora for an island of this size. The small number of adventives highlights the lush development of the native plant communities. The three species recorded by Adams (1969) but not found in the present survey are incorporated in the list, as are Dichon-

78 Fig. 3. View from (he summit of Motuharakeke Island looking east at steep dome forming the eastern extremity of the island. Photograph: B.W. Hayward. dra and Chenopodium which were collected from the island by A.B Stephenson in 1967. These additions bring the total flora to 34 taxa.

FERN Solatium aviculare Chenopodium allanii Asplenium flaccidum LIANE Dichondra repens subsp. haurakiense Muehlenbeckia complexa Disphyma australe TREES AND SHRUBS GRASSES Parietaria debilis Coprosma repens Agropyron kirkii Phytolacca octandra* Hymenanthera novae- A vena fatua* Polycarpon tetraphyllum * zelandiae Chionochloa bromoides Rhagodia triandra Melicytus ramiflorus Lachnagrostis filiformis Salicornia australis Metrosideros excelsa Phalaris minor* Samolus repens Myoporum laetum Poa annua* Senecio lautus Paratrophis banksii MONOCOT HERBS Solanum nigrum* Phormium tenax Arthropodium cirratum S. nodiflorum Pittosporum crassifolium Cyperus ustulatus Spergularia marginata Pseudopanax lessonii DICOT HERBS Wahlenbergia gracilis

Motuhuia This, the southernmost of the Cavalli Islands, supported a very discon• tinuous and unhealthy looking vegetation. On the summit, scattered Scirpus nodosus, dune tauhinu and patotara were found, with occasional young pohutukawa and houpara. It is possible that the summit vegetation had been recently burnt off, although it appeared unlikely that there would ever 79 have been much vegetation to burn. Asplenium flaccidum subsp. haurakiense occurred in very low crevices on the southern side of the island. A flora of 26 taxa was recorded.

FERN GRASSES Sporobolus africanus * Asplenium flaccidum Aira caryophyllea * MONOCOT HERB subsp. haurakiense A. multiculmis* Scirpus nodosus TREES AND SHRUBS Anthoxanthum odoratum * DICOT HERBS Cassinia retorta A vena fatua" Cyathodes fraseri Coprosma repens Bromus mollis* Disphyma australe Metrosideros excelsa Chionochloa bromoides Hypochoeris radicata * Phormium tenax Lachnagrostis filiformis Salicornia australis Pseudopanax lessonii Notodanthonia biannularis Samolus repens LIANE N. unarede Senecio lautus Muehlenbeckia complexa Parapholis incurva* Spergularia marginata

Motukahakaha This small vegetation-capped rock dome lies between Kahangaro and Piraunui in the south-west of the group. The vegetation has probably remained unmodified due to the difficulties experienced in climbing up to it. From a distance, the island appeared to support a small area of scrubby pohutukawa. On closer examination, minor amounts of taupata and Strath- more weed, and several grasses and herbs were found. A flora of 11 taxa was recorded while climbing up the north-east side of the island.

TREES AND SHRUBS Chionochloa bromoides Disphyma australe Coprosma repens Sporobolus africanus* Sagina apetala* Metrosideros excelsa Vulpia bromoides* Samolus repens Pimelea prostrata DICOT HERBS Senecio lautus GRASSES Cyathodes fraseri

Motukaroro The following list of 26 taxa was recorded by Mr D.J. Court for this small islet joined to Motukawanui at low tide.

FERN Muehlenbeckia complexa DICOT HERBS Asplenium flaccidum GRASSES Anagallis arvensis* subsp. haurakiense A vena fatua* Apium australe TREES AND SHRUBS Chionochloa bromoides Crepis capillaris * Cassinia retorta Cortaderia splendens Cyathodes fraseri Coprosma repens Dactylis glomerata* Disphyma australe Metrosideros excelsa Notodanthonia biannularis Hypochoeris radicata* Phormium tenax MONOCOT HERBS Lotus angustissimus* Pimelea prostrata Arthropodium cirratum Plantago lanceolata* Pseudopanax lessonii Astelia banksii Salicornia australis LIANE Scirpus nodosus Tetragonia trigyna

80 Motukawaiti (Step Island) The largest island surveyed in the present study and the second-largest in the Cavalli Group. Despite farming and the maintenance of improved pastures, a wide variety of habitats existed on the island, which, together with one or two refuge areas inaccessible to stock, gave rise to a very large and varied flora. The bulk of the island was grassed, with improved clover/rye/browntop pastures around the homestead and along the summit of the island. The upper beach (left foreground, Fig. 2) provided a very different habitat supporting quantities of Mexican tea (Chenopodium ambrosioides), sea rocket, orache (A triplex hastata) and saltwort (Salsola kali). Vegetation on the high cliffs along the eastern two-thirds of the north coast was confined to clumps of Chionochloa, coastal toetoe (Cortaderia splendens), N.Z. flax and dune tauhinu with occasional pohutukawa trees. Apparent manuka scattered through the pasture in the south-east of the island somewhat surprisingly turned out to be dune tauhinu. Remnant native forest trees occurred on cliffs and in steep gullies along the southern side of the island with native grasses such as meadow rice grass beneath them. Cattle-shorn shrubs of waiuatua (Rhabdothamnus solandri) also sur• vived in sheltered places. A very steep block at the eastern end of the island was inaccessible to cat• tle. The northern side was cliffed, but the steep southern slopes supported dense groves of N.Z. flax, asteliads (Astelia banksii and A. solandri) with scattered clumps of bracken, hangehange and Coprosma macrocarpa. A small area of more mature coastal forest on the extreme south-east cor• ner of the island was probably the best developed coastal forest seen in the whole group. Tawapou (Planchonella novo-zelandica) was the dominant canopy tree, up to 30cm in diameter at breast height. Other canopy and sub- canopy trees and shrubs included wharangi (Melicope ternata), karo, rangiora (Brachyglottis repanda), hangehange, mahoe, kawakawa, lacebark (Hoheria populnea), houpara and Coprosma macrocarpa. The native jasmine, kaiwhiria (Parsonsia heterophylla) was an abundant liane and Asplenium lucidum, Polystichum richardii, Pyrrosia serpens, Peperomia urvilleana and renga lily provided the groundcover. Two 15cm tall, single-stemmed, single-flowered plants of Hibiscus trionum were found growing in pasture on the steep slopes behind the homestead. A flora of 180 taxa was recorded.

FERNS B. lanceolatum Pteridium aquilinum Adiantum aethiopicum Cyathea medullaris var. esculentum A. hispidulum Dicksonia squarrosa Pteris comans Asplenium flaccidum Doodia media P. tremula subsp. haurakiense Paesia scaberula Pyrrosia serpens A. lucidum Phymatodes diversifolium TREES AND SHRUBS Blechnum capense Polystichum richardii Araucaria excelsa*

SI Brachyglottis repanda D. micrantha Crepis capillaris* Carmichaelia aligera Festuca arundinacea* Cyathodes fraseri Cassinia retorta Holcus lanatus* Daucus carota* Coprosma macrocarpa Hordeum murinum* Dichondra repens C. repens Lachnagrostis filiformis Disphyma australe Cordyline australis Lagurus ovatus* Erigeron floribundus* Coriaria arborea Lolium perenne* Foeniculum vulgare* Cupressus macrocarpa * Microlaena stipoides Galium parisiense * Cyathodes fasciculata Notodanthonia biannularis Geranium homeanum Ficus elastica decora* N. racemosa G. molle* Geniostoma ligustrifolium Oplismenus imbecillis G. sp. (unnamed) Hoheria populnea Parapholis incurva* G. calviceps* Lagunaria patersonii* P. strigosa* Gnaphalium gymnocephalum Leptospermum scoparium Paspalum dilatatum* G. luteo-album Macropiper excelsum P. scrobiculatum G. spicatum* Melicope ternata Pennisetum clandestinum * Haloragis erecta Melicytus ramiflorus Poa anceps Hibiscus trionum Metrosideros excelsa P. annua* Hypochoeris radicata* Musa paradisiaca P. seticulmis Linum Trigynum* subsp. sapientum* Polypogon monspeliensis * Lotus angustissimus* Nerium oleander* Sporobolus africanus * L. corniculatus* Phormium tenax Vulpia bromoides* L. pedunculatus* Pimelea prostrata MONOCOT HERBS L. subbiflorus* Pinus radiata* Arthropodium cirratum Malva parviflora* Pittosporum crassifolium Astelia banksii Medicago polymorpha* Planchonella novo- A. solandri Melilotus indica* zelandica Carex breviculmis Orobanche minor* Podocarpus totara C. flagellifera Oxalis corniculata Pseudopanax lessonii C. pumila Parentucellia viscosa* Rhabdothamnus solandri C. virgata Peperomia urvilleana Solanum sodomeum* Collospermum hastatum Phytolacca octandra* Ulex europaeus* Cyperus ustulatus Plantago hi net la* ? Yucca sp. * Juncus bufonius* P. lanceolata* LIANES J. gregiflorus P. major* Calystegia sepium J. planifolius C. tugoriorum Leptocarpus similis Polycarpon tetraphyllum * Muehlenbeckia complexa Scirpus cernuus Prunella vulgaris* Parsonsia heterophylla S. chlorostachyus Ranunculus parviflorus* GRASSES S. nodosus Rubus fruticosus agg.* Agropyron kirkii Thelymitra longifolia Rumex acetosella* Agrostis tenuis* DICOT HERBS R. brownii* Aira caryophyllea* Anagallis arvensis* R. conglomeratus* A. multiculmis* Apium australe R. crispus* Anthoxanthum odoratum* A triplex hastata* Sagina apetala* Avena fatua* Cakile maritima* Salicornia australis Bothriochloa macra* Callitriche stagnalis Salsola kali* Briza minor* Calystegia soldanella Samolus repens Bromus mollis* Carduus pycnocephalus* Senecio bipinnatisectus * B. unioloides* Centaurium erythraea* S. lautus Chionochloa bromoides Centella uniflora Silene gallica * Cortaderia splendens Cerastium glomeratum* Silybum marianum* Cynodon dactylon* Chenopodium ambrosioides* Sisymbrium officinale* Dactylis glomerata* Cirsium vulgare* Solanum nigrum* Deyeuxia billardieri Coronopus didymus * Sonchus oleraceus * Dichelachne crinita Stellaria media*

82 S. parviflora T. glomeratum* Veronica arvensis* Tetragonia trigyna T. repens* Wahlenbergia gracilis Trifolium dubium* Verbena lit oral is*

Motukeokeo No landing was made on this tall, steep dome lying close to Motumuka. The steeper slopes supported clumps of Chionochloa, N.Z. flax and wharawhara (Astelia banksii). Scattered shrubby pohutukawa, hange• hange, houpara and Hymenanthera occurred in a slight 'gully' below the largest pohutukawa tree. Taupata became common in lower crevices with Samolus, iceplant and tufts of Stipa teretifolia just above high water mark. A patch of shrubby coastal species had developed on the eastern side of the dome where slopes were slightly less severe.

Motumahanga Another of the small islands joined to Motukawanui at low tide, Motumahanga was mostly grassy with some good N.Z. flax groves develop• ing. A large pohutukawa grew on the south-eastern corner of the island and a few shrubs of hangehange and Coprosma macrocarpa were scattered amongst the grasses. A flora of 80 taxa, large for an island of this size, was recorded. The species numbers are boosted by two factors — the proximity of Motu• kawanui as a source for the many adventives; and the shelter provided by Motukawanui from wind and high seas.

FERNS Aira caryophyllea* Carex flagellifera Adiantum hispidulum A. multiculmis* Scirpus nodosus Asplenium flaccidum Anthoxanthum odoratum* Thelymitra longifolia subsp. haurakiense A vena fatua * DICOT HERBS A. lucidum Bothriochloa macra* Anagallis arvensis* Doodia media Briza minor* Centaurium erythraea* Phymatodes diversifolium Bromus mollis* Centella uniflora Pyrrosia serpens Chionochloa bromoides Cerastium glomeratum* TREES AND SHRUBS Dactylis glomerata * Cyathodes fraseri Cassinia retorta Deyeuxia billardieri Dichondra repens Coprosma macrocarpa Dichelachne crinita Disphyma australe C. repens D. micrantha Erigeron floribundus * Cyathodes fasciculata Holcus lanatus* Euphorbia peplus* Geniostoma ligustrifolium Lachnagrostis filiformis Geranium sp. (unnamed) Melicytus ramiflorus Microlaena stipoides G. retrorsum* Metrosideros excelsa Notodanthonia biannularis Gnaphalium gymnocephalum* Phormium tenax N. racemosa G. luteo-album Pimelea prostrata N. unarede Haloragis erecta Poly gala my r I (folia * Parapholis incurva * Hypochoeris radical a* Pseudopanax lessonii Paspalum dilatatum* Linum trigynum* Solanum sodomeum* Poa anceps Lotus angustissimus* LIANE Sporobolus africanus* L. subbiflorus* Muehlenbeckia complexa Vulpia bromoides* Orobanche minor* GRASSES MONOCOT HERBS Oxalis corniculata Agropyron kirkii Astelia banksii 83 Parentucellia viscosa* Salicornia australis Sonchus oleraceus* Peperomia urvilleana Samolus repens Tetragonia trigyna Polycarpon tetraphyllum* Senecio lautus Trifolium dubium* Rumex conglomerate* Solanum nodiflorum T. glomeratum* Sagina apetala*

Motumuka A major archaeological site made up of numerous pits and terraces (Hayward et at. 1979) ran along the summit ridge of this island, indicating early modification of the vegetation. As more time was spent on this island than any other the vegetation was studied in more detail. The island's topography was dominated by a more or less gentle slope rising from just above sea level on the south-west coast to the summit of the cliffs forming the north-eastern coast. Forest was developing in the shelter of a small cen• tral valley. I will describe the vegetation encountered while ascending from sea level through this valley to the summit of the northern cliffs. The following plants occupied extreme coastal rock crevices: glasswort, Samolus repens, Scirpus nodosus, Leptocarpus similis, shore groundsel and N.Z. flax. It is interesting to note that in this habitat of high stress all the plants are native to New Zealand. Immediately inland of this zone was a mixed community including the grasses Bromus mollis, cocksfoot (Dactylis glomerata), long-hair plume grass, paspalum and Poa anceps; the herbs broomrape (Orobanche minor), patotara and renga lily; the ferns bracken, Doodia and rosy maidenhair; and small shrubs of houpara, koromiko (Hebe stricta var. stricta), ngaio and N.Z. flax. In this zone, the earlier activities of man and the instability of the earth and weathered rock on the steep coastal slopes were reflected in the occurrence of adventive weeds and grasses. Moving further away from the sea, one entered the outer fringes of the coastal forest. A 2-3 metre high canopy was formed mainly by houpara, with smaller amounts of Coprosma macrocarpa, Hymenanthera and karaka (Corynocarpus laevigatus). Large numbers of karaka seedlings were present in well-lit areas, with a moderate groundcover of ferns, Carex flagellifera and rare terrestrial kahakaha (Astelia solandri). Occasional weak, straggling plants of rosy maidenhair appeared to be remnants from the earlier mixed community now seen seaward of this more mature vegeta• tion. Within the valley the vegetation was more mature again, with occasional 8-10m tall pohutukawas standing above wharangi forest. The majority of the wharangi were in the 5-10cm diameter at breast height size class, and were producing large quantities of seedlings. Both hangehange and mahoe were present as shrubs, with huge crowns of Polystichum richardii and Pteris comans common on the forest floor. Exposed rock faces near the top of the gully provided a substrate for colonies of Peperomia urvilleana. Above the coastal forest valley, the ground dried out and the vegetation became open and scrubby. The discontinuous canopy (3-4m high) was pro- 84 vided by houpara (approximately 90%), Coprosma macrocarpa (8%) and mahoe (2%). The drier conditions were reflected in a reduced groundcover of Gahnia lacera, Doodia and Phymatodes diversifolium. Occasional sene• scent manuka were found amongst the houpara together with dead and rot• ting manuka trunks. This community continued to within a few metres of the ridge/clifftop above the coastal valley. The summit ridge supported low scrub interspersed with grassy areas. Young pohutukawa trees were scattered amongst low manuka, dune tauhinu, N.Z. flax, mingimingi and tauhinu with numerous bronze col• oured young totara trees. Prickly hakea (Hakea sericea) was an important constituent of this scrub on a small plateau area at the eastern end of the summit ridge. 43 plants, ranging from small seedlings to lm tall densely interlaced shrubs were cut out and thrown over the cliffs into the sea. From dead remains lying around it was obvious that an earlier attempt had been made to eradicate this pest. Despite disposal of the plants in this instance, enough seeds will be present amongst the scrub for further re-establishment. Therefore, control work will be necessary on a regular basis for some time into the future. The extremely dry, exposed eroding clifftops supported the usual group of plants for this habitat, viz. danthonias, red leg grass, patotara, suckling clover (Trifolium dubium) and Scirpus nodosus. Three further stages in the development of climax vegetation on Motu- muka were seen at the eastern end of the island (not covered in the 'transect' from sea-level to summit already described). The ridge from the summit down to the south-eastern corner of the island appeared to have been burnt off within the last one or two years. The area immediately opposite the highest point of Motukeokeo was the most recently burnt, with abundant surface charcoal present and some shrubs showing fire damage. Low shrubs of koromiko, tauhinu, manuka, N.Z. flax and cabbage trees (Cordyline australis) were scattered amongst the grasses and Scirpus nodosus. Right at the eastern end of the island was an area of rough pasture growing amongst fine shattered surface rock. Danthonias, Agropyron kirkii and ratstail were the most common species with lesser amounts of sweet vernal, Yorkshire fog (Holcus lanatus), catsear, patotara, centaury and Scirpus nodosus. The last type of vegetation encountered was 2 metre tall manuka scrub, which covered most of the southern slopes east of the valley of coastal forest; it appeared that the tall houpara community had developed from this type of scrub. The presence of several large and spreading clumps of houpara in the manuka scrub provided evidence for this. A flora of 98 taxa was recorded.

FERNS Cyathea medullaris Pteridium aquilinum Adiantum hispidulum Doodia media var. esculentum Asplenium flaccidum Phymatodes diversifolium Pteris comans subsp. haurakiense Polystichum richardii TREES AND SHRUBS A. lucidum Cassinia retorta 85 Coprosma macrocarpa Briza minor* DICOT HERBS C. repens Bromus mollis* Anagallis arvensis * Cordyline australis Chionochloa bromoides Centaurium erythraea* Corynocarpus laevigatus Cortaderia splendens Centella uniflora Cyathodes fasciculata Dactylis glomerata* Crepis capillaris* Geniostoma ligustrifolium Deyeuxia billardieri Cyathodes fraseri Hakea sericea* Dichelachne crinita Dichondra repens Hebe stricta var. stricta D. micrantha Disphyma australe Hymenanthera novae- Holcus lanatus* Erigeron floribundus* zelandiae Lachnagrostis filiformis Euphorbia peplus* Leptospermum scoparium Microlaena stipoides Geranium retrorsum* Melicope ternata Notodanthonia biannularis Gnaphalium gymnocephalum * Melicytus ramiflorus N. racemosa G. involucratum Metrosideros excelsa N. una rede G. luteo-album Myoporum laetum Oplismenus imbecillis G. simplicicaule Myrsine australis Parapholis incurva* G. spicatum* Phormium tenax Paspalum dilatatum* Haloragis erecta Pimelea prostrata Poa anceps Hypochoeris radicata* Pittosporum crassifolium P. seticulmis Lobelia anceps Podocarpus totara Sporobolus africanus* Orobanche minor* Pomaderris phylicifolia Stipa teretifolia Oxalis corniculata var. ericifolia Vulpia bromoides* Peperomia urvilleana Pseudopanax lessonii MONOCOT HERBS Plantago lanceolata* LIANE Arthropodium cirratum Salicornia australis Astelia banksii Samolus repens Muehlenbeckia complexa A. solandri Senecio lautus GRASSES Carex breviculmis Silene gallica * Agropyron kirkii C. flagellifera Sonchus oleraceus* Aira caryophyllea * Gahnia lacera Tetragonia trigyna A. multiculmis* Leptocarpus similis Trifolium dubium* Anthoxanthum odoratum* Scirpus nodosus A vena fatua* Thelymitra longifolia Bothriochloa macro*

Moturahurahu Another of the islands lying close to Motukawanui on which an archae• ological site was recorded (Hayward el al. 1979). The steep, rocky northern slopes were mainly covered in grasses, with many annual weed species, clumps of wharawhara, occasional pohutukawa trees and patches of the ferns Pellaea, Cheilanthes, Pyrrosia, Phymatodes and Asplenium lucidum. The flattened summit was mainly grassy, with scattered young bushes of manuka, mingimingi, N.Z. flax and cabbage tree. The south side of the island supported developing coastal forest with common houpara, Coprosma macrocarpa, hangehange, wharangi and pohutukawa. A sharp, rocky ridge led down toward Motukawanui on which grew numerous sun orchids (Thelymitra longifolia) and several bushes of the adventive sweet pea shrub (Polygala myrtifolia). A flora of 67 taxa was recorded.

FERNS A. lucidum Phymatodes diversifolium Adiantum hispidulum Cheilanthes sieberi Pteridium aquilinum Asplenium flaccidum Doodia media var. esculentum subsp. haurakiense Pellaea falcata Pyrrosia serpens 86 TREES AND SHRUBS Anthoxanthum odoratum* Centaurium erythraea* Coprosma macrocarpa A vena fatua* Centella uniflora C. repens Bothriochloa macra* Crepis capillaris* Cordyline australis Briza minor* Cyathodes fraseri Cyathodes fasciculata Bromus mollis* Dichondra repens Geniostoma ligustrifolium Chionochloa bromoides Disphyma australe Leptospermum scoparium Dactylis glomerata * Erigeron floribundus* Melicope ternata Dichelachne crinita Hypochoeris radicata* Metrosideros excelsa Microlaena stipoides Lotus angustissimus* Phormium tenax Notodanthonia biannularis L. subbiflorus* Pittosporum crassifolium Paspalum dilatatum* Medicago polymorpha* Podocarpus totara Sporobolus africanus* Orobanche minor* Poly gala myrtifolia* Vulpia bromoides* Parentucellia viscosa* Pomaderris phylicifolia MONOCOT HERBS Polycarpon tetraphyllum* var. ericifolia Arthropodium cirratum Samolus repens Pseudopanax lessonii Astelia banksii Solanum nigrum* LIANE Carex breviculmis Sonchus oleraceus* Muehlenbeckia complexa C. flagellifera Trifolium dubium* GRASSES Scirpus nodosus T. glomeratum* Agropyron kirkii Thelymitra longifolia Wahlenbergia gracilis Aira caryophyllea* DICOT HERBS A. multiculmis* Anagallis arvensis*

Motutakupu The eastern outlier of the northern group of islands, Motutakupu (less than one hectare in area) supported a lush and almost entirely native vegeta• tion cover. The island was sheer-sided apart from a crevice on the north• west corner which could be climbed. This has probably helped ensure less burning off of the vegetation than on the other islands. Despite the steep sides, the island had a flat crown covered in a good depth of friable, humic soil. Scattered over the cliffs and forming larger areas at the clifftops were glasswort, N.Z. iceplant, shore groundsel and renga lily. Behind this zone were areas of low taupata scrub amongst which a small number of seabird burrows were seen. Further marginal areas supported groves of N.Z. flax, with numerous seedlings of N.Z. pellitory and small-flowered nightshade (Solanum nodiflorum) around them. The major part of the summit area was clothed in a 4-5m high canopy of houpara, mahoe and karo, with younger plants of N.Z. broom, totara and Coprosma macrocarpa appearing. Apart from occasional clumps of Asplenium flaccidum subsp. haurakiense, groundcover was non-existent due to the density of the canopy and resultant low interior light intensity. Adams (1969) noted that some attempt had been made at burning prior to his survey. This presumably corresponds with the present extensive flax groves. He noted that bird numbers could be expected to decline as plant succession progressed and this was borne out by a brief count of burrows. Numbers were well below those estimated by Adams. A flora of 22 taxa was recorded.

87 FERN Phormium tenax Scirpus nodosus Asplenium flaccidum Pittosporum crassifolium DICOT HERBS subsp. haurakiense Podocarpus totara Disphyma australe TREES AND SHRUBS Pseudopanax lessonii Parietaria debilis Carmichaelia aligera LIANE Rhagodia triandra Coprosma macrocarpa Muehlenbeckia complexa Salicornia australis C. repens GRASS Senecio lautus Hymenanthera novae- Bromus unioloides* Solanum nodiflorum zelandiae MONOCOT HERBS Sonchus oleraceus * Melicytus ramiflorus Arthropodium cirratum Tetragonia trigyna

Motutapere Another roughly circular island, which rose more or less gently from the eastern shores to the summit of the steep slopes and cliffs forming the western side of the island. Adams (1969) noted that the island had been burned over within 12 months of his visit, with only one small patch of mahoe and Coprosma macrocarpa remaining. Regeneration had only advanced to the grasses/rush stage, with scattered N.Z. flax and Chionochloa (Adams 1969). By contrast, the dominant vegetation 10 years later during the present survey was a 0.5-lm high scrub of N.Z. flax, bracken, N.Z. broom and manuka. Scattered amongst the scrub were numerous clumps of coastal toetoe — more than on any other island in the group. A patch of coastal forest existed in a small gully on the south side of the island, below a group of pohutukawas. This was almost certainly Adam's "small patch of mahoe/Coprosma macrocarpa" which survived the 1968 burning. Several houpara and karo had established in the intervening years, along with a groundcover of Doodia, ponga (Cyathea dealbata), Asplenium flaccidum subsp. haurakiense, A. lucidum and Carex flagellifera. A flora of 77 taxa was recorded. Adams (1969) noted that some Hibiscus trionum was present. Despite searching in grassy habitats similar to those supporting Hibiscus on Haraweka, none was found during the present survey.

FERNS Leptospermum scoparium Briza minor* Asplenium flaccidum Melicytus ramiflorus Bromus mollis* subsp. haurakiense Metrosideros excelsa Chionochloa bromoides A. lucidum Myrsine australis Cortaderia splendens Cheilanthes sieberi Phormium tenax Dactylis glomerata * Cyathea dealbata Pimelea prostrata Deyeuxia billardieri Doodia media Pittosporum crassifolium Dichelachne crinita Pteridium aquilinum LIANES Lachnagrostis filiformis var. esculentum Calystegia tugoriorum Notodanthonia biannularis TREES AND SHRUBS Muehlenbeckia complexa N. racemosa Carmichaelia aligera GRASSES N. unarede Cassinia retorta Aira caryophyllea * Parapholis incurva* Coprosma macrocarpa A. multiculmis* Paspalum dilatatum* C. repens Anthoxanthum odoratum* P. scrobiculatum Geniostoma ligustrifolium A vena fatua* Poa anceps 88 P. seticulmis Crepis capillar is * Lobelia anceps Sporobolus africanus * Cyathodes fraseri Lotus angustissimus* MONOCOT HERBS Dichondra repens Orobanche minor* Arthropodium cirratum Disphyma australe Oxalis corniculata Carex breviculmis Erigeron floribundus * Polycarpon tetraphyllum * C. flagellifera Eupatorium adenophorum * Sagina apetala* Gahnia lacera Geranium sp. (unnamed) Salicornia australis Scirpus nodosus Gnaphalium audax Samolus repens Thelymitra longifolia G. gymnocephalum* Senecio lautus DICOT HERBS G. luteo-album Silene gallica* Anagallis arvensis* G. spicatum Sonchus oleraceus * Centaurium erythraea * Haloragis erecta Spergularia marginata Centella uniflora Hypochoeris radicata * Trifolium dubium* Wahlenbergia gracilis

Nukutanga (Fig. 4) This large, cliff-bound island rises to 108m above sea level, where an automatic light station is situated. Access was difficult, although the elevated upper slopes were gentle and easily explored. These upper slopes were drained by two shallow watersheds, draining over the western and southern cliffs. Goats were present on the island in 1969. Adams (1969) stated that "much of the slopes are in short cropped pasture, with a small stand of Myrsine australis, mahoe, with some wharangi and milk tree". He con• tinued "Little regeneration occurs. The unpalatable ngaio is rapidly col• onising eastern slopes and can be expected to cover most of the island within a few years." Goats had been eradicated some time before the present survey, allowing an exceptional burst of regeneration. Most of the southern watershed was clothed in coastal forest (Fig. 4). Marginal areas had a canopy up to 5m tall composed of cabbage trees and sparse, spindly ngaio trees. Beneath this canopy was a dense layer of mahoe to 1.5m tall. Beneath this again were abundant mapou (Myrsine australis) seedlings from 30-40cm tall, and an almost continuous groundcover of Hydrocotyle elongata. Moving away from the margins of the forest, tawapou seedlings to 20cm tall became locally abundant. The bulk of the forest canopy was composed of mapou, large-leaved milk tree and wharangi. Mahoe from 1-1.5m again provided the shrub layer, with densely packed large-leaved milk tree seed• lings (4-5cm high) and Hydrocotyle providing groundcover. A clear exam• ple of the state of regeneration was provided by one 6m high large-leaved milk tree (20cm D.B.H.) below whose canopy spread of some 9m2 were an estimated 1375 3cm seedlings per m2. The second watershed was largely grassed, although some spread of shrubs and trees from the forested catchment was occurring. In particular, cabbage trees and low, spreading ngaio bushes were pushing out towards the light station. The grassland was dominated by paspalum and prairie grass (Bromus unioloides), with dense tangles of wire vine along the course 89 Fie 4. View of Nukutaunga Island looking northeast from Haraweka Island. The small, steep island to the left of Nukutaunga is Tuturuowai. Photograph: B.W. Hayward. of the dried up stream. Large, many-branched plants of Hibiscus trionum were found amongst the tall grasses on the north-facing side of the water• shed just above the stream course. It appeared that the grasses and wire vine would completely overtake the Hibiscus within a year or two. Small pockets of coastal forest occurred in several sheltered places around the cliffs and were providing the nuclei for areas of strong regenera• tion. One such area just above the south-west cliffs had a canopy 5-6m tall of mahoe, wharangi, ngaio, Coprosma macrocarpa and cabbage tree. Although no adults were seen, large-leaved milk tree seedlings were com• mon. A small number of flowering shrubs of waiuatua had established, and a good groundcover was provided by wire vine, Oplismenus, N.Z. spinach, Hydrocotyle, Carex flagellifera and Polystichum richardii. A flora of 100 taxa was recorded.

FERNS Pyrrosia serpens Hymenanthera novae- Adiantum hispidulum TREES AND SHRUBS zelandiae Asplenium lucidum Carmichaelia aligera Leptospermum scoparium Doodia media Cassinia retorta Macropiper excelsum Phymatodes diversifolium Coprosma macrocarpa Me I i cope tenia ta Polystichum richardii C. repens Melicytus ramiflorus Pteridium aquilinum Cordyline australis Metrosideros excelsa var. esculentum Corynocarpus laevigatus Myoporum laetum Pteris comans Myrsine australis 90 Paratrophis banksii N. unarede Eupatorium adenophorum * Pimelea prostrata Oplismenus imbecillis Geranium sp. (unnamed) Planchonella novo- Parapholis incurva Gnaphalium luteo-album zelandica Paspalum dilatatum Haloragis erecta Rhabdothamnus solandri P. scrobiculatum H. incana DANES Poa anceps Hibiscus trionum Calystegia tugoriorum Sporobolus africanus Hydrocotyle elongata Muehlenbeckia complexa Vulpia bromoides Hypochoeris radicata* Parsonsia heterophylla MONOCOT HERBS lobelia anceps GRASSES Arthropodium cirratum Lotus angustissimus* Agropyron kirkii Astelia bunk si i I. . subbiflorus * Aira caryophyllea A. solandri Modiola caroliniana* A. multiculmis Carex breviculmis Orobanche minor* Anthoxanthum odoratum C. flagellifera Oxalis corniculata A vena fatua C'. lambertiana Parietaria debilis Briza minor C. spinirostris Physalis peruviana * Bromus diandrus Cyperus ustulatus Phytolacca octandra* B. mollis Juncus gregiflorus Polycarpon tetraphyllum * B. unioloides Scirpus nodosus Salicornia australis ( Catapodium rigidum DICOT HERBS Samolus repens Chionochloa bromoides Anagallis arvensis* Senecio lautus Dactylis glomerata Centaurium erythraea* Siegsbeckia orientalis Silene gallica* Deyeuxia billardieri Centella uniflora Solanum nigrum* Dichelachne crinita Crepis capillaris * Sonchus oleraceus* Holcus lunulas Cyathodes fraseri Tetragonia trigyna Microlaena stipoides Dichondra repens Trifolium dubium* Notodanthonia biannularis Disphyma australe N. racemosa Erigeron floribundus*

Panaki A relatively long, narrow island, Panaki was divided into a number of watersheds falling from steep northern cliffs and slopes to lower cliffs or a sandy beach on the south coast. Landings were made on the sandy beach in Vegetable Bay. Just back from the beach in a small valley bottom was an area of coastal forest that had escaped burning for several decades at least. It was dominated by the offshore island kawakawa (Macropiper excelsum var. ma/us), with lesser amounts of karaka, mahoe, hangehange and Hymenanthera. N.Z. flax and cabbage trees formed a dense sward right around the forest, and mawhai (Sicyos angulata) was found scrambling through the N.Z. flax immediately behind the beach. The whole of the area to the west of this area of forest had been burned off within a few months of our visit. Blackened stems were common, and evidence of birding in the form of large numbers of collapsed burrows were seen. Apart from some plants of N.Z. flax putting out their first green leaves, vegetation in this area was confined to annual weeds, the most strik• ing of which was the native kopata (Pelargonium inodorum). Cliffs and steep coastal slopes provided a refuge for native species, par• ticularly pohutukawa. Almost the whole length of the northern clifftops

91 had a low mat of patotara, Strathmore weed, dune tauhinu, centella and danthonia (Notodanthonia racemosa). The eastern slopes of the valley behind the beach had also been disturbed relatively recently and dense stands of wild radish were present. Almost the whole of the remainder of the island appeared to have been burned off at some time or other over the last ten years. Vegetation varied from almost pure groves of N.Z. flax (the youngest) to a denser N.Z. flax/Scirpus nodosus community with various amounts of N.Z. broom, cabbage tree, mahoe, Coprosma macrocarpa and tutu. A flora of 115 taxa was recorded.

FERNS B. unioloides* Dichondra repens Adiantum hispidulum Chionochloa bromoides Disphyma australe Asplenium flaccidum Cortaderia splendens Epilobium rotundifolium subsp. haurakiense Cynodon dactylon * Erigeron floribundus * A. lucidum Dactylis glomerata * Geranium sp. (unnamed) Doodia media Deyeuxia billardieri Gnaphalium gymnocephalum * Phymatodes diversifolium Dichelachne crinita G. luteoalbum Pteridium aquilinum Lagurus ovatus* G. sphaericum* var. esculentum Microlaena stipoides G. spicatum* Pyrrosia serpens Notodanthonia biannularis Haloragis erecta TREES AND SHRUBS N. racemosa Hypochoeris radicata * Carmichaelia aligera N. unarede Linum Trigynum* Cassinia retorta Oplismenus imbecillis Lotus angustissimus* Coprosma macrocarpa Parapholis incurva* L. subbiflorus* C. repens Paspalum dilatatum* Medicago polymorpha* Cordyline australis P. paspalodes* Melilotus indica * Coriaria arborea P. scrobiculatum Modiola caroliniana* Corynocarpus laevigatas Pennisetum clandestinum * Orobanche minor* Geniostoma liqustrifolium Phalaris minor* Oxalis corniculata Hymenanthera novae- Poa anceps Parentucellia viscosa * zelandiae P. seticulmis Parietaria debilis Macropiper excelsum Sporobolus africanus* Pelargonium inodorum Melicope ternata Stenotaphrum secundatum * Peperomia urvilleana Melicytus ramiflorus Vulpia bromoides* Phytolacca octandra* Metrosideros excelsa MONOCOT HERBS Polycarpon tetraphyllum * Phormium tenax Arthropodium cirratum Raphanus raphanistrum* Pimelea prostrata Astelia banksii R. sativus* Pittosporum crassifolium Carex breviculmis Rhagodia triandra Rumex crispus* Poly gala myrtifolia* C. lambertiana Salicornia australis Pseudopanax lessonii Cyperus ustulatus Samolus repens LIANES Scirpus nodosus Senecio lautus Calystegia tugoriorum Thelymitra longifolia Silene gallica* Muehlenbeckia complexa DICOT HERBS Solanum nigrum* Sicyos angulata Anagallis arvensis* Sonchus oleraceus * GRASSES A triplex hastata* Stellar la media* Agropyron kirkii Brassica oleracea * Tetragonia trigyna Aira caryophyllea* Cakile maritima* Trifolium dubium* A. multiculmis* Centaurium erythraea* T. glomeratum* Anthoxanthum odoratum* Centella uniflora Wahlenbergia gracilis A vena fatua* Cirsium vulgare* Briza minor* Crepis capillar is* Bromus mollis* Cyathodes fraseri 92 Piraunui This very steep island appeared to have been greatly damaged by removal of the vegetation and possible occupation by the prehistoric Maori, with resultant slumping and loss of soils. Particularly bad infestations of gorse (U/ex europaeus) were found on the scree slope leading up from the eastern beach and throughout the summit scrub. Where gorse was absent on some of the steeper rocky slopes, wharawhara, N.Z. flax, pohutukawa and a variety of ferns were growing luxuriously. As on several of the southern islands in the group, numbers of young totara trees were found on the summit. The fern Pellaea falcata noted by Adams (1969) was not located during the present survey. A flora of 44 taxa was recorded.

FERNS LIANE Anagallis arvensis* Adiantum hispidulum Calystegia tugoriorum Dichondra repens Asplenium flaccidum GRASSES Disphyma australe subsp. haurakiense Briza minor* Haloragis erecta A. lucidum Bromus mollis* Hypochoeris radicata * Pellaea falcata Chionochloa bromoides Lobelia anceps Phymatodes diversifolium Deyeuxia billardieri Mel dolus indica* Pyrrosia serpens Oplismenus imbecillis Peperomia urvilleana TREES AND SHRUBS Parapholis incurva* Polycarpon tetraphyllum * Coprosma macrocarpa Paspalum dilatatum* Sagina apetala* C. repens Poa anceps Salicornia australis Cyathodes fasciculata Vulpia bromoides* Samolus repens Phormium tenax MONOCOT HERBS Senecio lautus Pittosporum crassifolium Arthropodium cirratum Silene gallica* Podocarpus totara Astelia banksii Sonchus oleraceus* Pseudopanax lessonii Scirpus nodosus Tetragonia trigyna Ulex europaeus* DICOT HERBS

Tarawera Although considerably larger in area than many of the small islets and rock stacks between Motukawanui and Motukawaiti, Tarawera exhibited a very much reduced plant cover due to its very low profile (Fig. 2) and its extreme exposure to heavy seas, particularly from the north-east. Conse• quently, its flora of five species was entirely made up of the most salt resis• tant native plants, and confined to rock crevices.

SHRUB Disphyma australe Spergularia marginata Coprosma repens Salicornia australis DICOT HERBS Senecio lautus

Te Anaputa This small island rose steeply from the water and appeared to have been little modified. Despite searching, no adventive plants were found. Coastal rockfaces on the south-west side of the island supported quantities of renga lily, glasswort, N.Z. iceplant and shore groundsel. Somewhat surprisingly, 93 numerous young sporelings of scented fern (Paesia scaberula) were found rather out of place in rock crevices barely above the high-tide splash zone. The most advanced vegetation was found on the upper western slopes and almost flat summit of the island. A fringe of taupata and Hymenanthera (with Rhagodia beneath) was followed by large pohutukawas, some houpara and a mature large-leaved milk tree. Both N.Z. pellitory and N.Z. spinach were found scrambling amongst the tree roots. A flora of 18 taxa was recorded.

FERNS Paratrophis banksii DICOT HERBS Asplenium flaccidum Pseudopanax lessonii Disphyma australe subsp. haurakiense LIANE Parietaria debilis Paesia scaberula Muehlenbeckia complexa Rhagodia triandra TREES AND SHRUBS GRASS Salicornia australis Coprosma repens Chionochloa bromoides Senecio lautus Hymenanthera novae- MONOCOT HERBS Spergularia marginata zelandiae Arthropodium cirratum Tetragonia trigyna Metrosideros excelsa Scirpus nodosus

Te Anaputaiti and Rocks Several barely vegetated rocks rising from 10-30m above sea level were scattered around Te Anaputa. The largest of these, Te Anaputaiti, sup• ported a very small area of low, mat-like taupata on its summit, with one plant of Hymenanthera. Lower crevices supported lush clumps of glasswort, with lesser amounts of shore groundsel, N.Z. iceplant and spurrey scattered amongst the higher crevices.

TREES AND SHRUBS DICOT HERBS Senecio lautus Coprosma repens Disphyma australe Spergularia marginata Hymenanthera novae- Salicornia australis zelandiae

Te Karo This tiny islet lay off the point separating Waiiti and Papatara Bays on the south-western coast of Motukawanui and could be reached by wading through thigh-deep water at low tide. As with many of the small islands lying close inshore to Motukawanui, Te Karo had been utilised by the prehistoric Maori and terraced. The summit platform and terraces were covered in sparse, low grass, with quantities of the fern Cheilanthes sieberi off the north-eastern side of the summit. A small area of pohutukawa, scrub and ferns had survived on the eastern slopes of the island. Despite the very small size of the island the proximity of Motukawanui as a seed source resulted in the recording of a flora of 45 taxa.

94 FERNS LIANE DICOT HERBS Adiantum hispidulum Muehlenbeckia complexa Centaurium erythraea* Asplenium flaccidum GRASSES Cyathodes fraseri subsp. haurakiense Aira caryophyllea* Dichondra repens Cheilanthes sieberi Anthoxanthum odoratum* Disphyma australe Phymatodes diversifolium A vena fatua* Erigeron floribundus Pteridium aquilinum Briza minor* Eupatorium adenophorum * var. esculentum Chionochloa bromoides Geranium retrorsum* Pyrrosia serpens Dichelachne crinita Gnaphalium gymnocephalum* TREES AND SHRUBS Notodanthonia biannularis Hypochoeris radicata * Carmichaelia aligera N. unarede Polycarpon tetraphyllum * Cassinia retorta Pou anceps Salicornia australis Coprosma repens Vulpia bromoides* Samolus repens Cyathodes fasciculata MONOCOT HERBS Senecio lautus Metrosideros excelsa Astelia banksii Silene gallica* Phormium tenax Carex flagellifera Solanum nigrum* Pimelea prostrata Microtis unifolia Tetragonia trigyna Pseudopanax lessonii Scirpus nodosus

Te Toi Another small island lying a few metres off Motukawanui. The summit was covered in low manuka/N.Z. flax/bracken scrub with the ferns Asplenium lucidum, A. flaccidum subsp. haurakiense and rosy maidenhair beneath. Right at the clifftops were small areas of patotara, Scirpus nodosus and grasses. A small area of hangehange, houpara, Coprosma macrocarpa and koromiko was found off the south side of the summit flat. The fern Asplenium obtusatum subsp. northlandicum was found in deep rock crevices on the steep northern side of the island. Despite apparently identical habitats on many of the islands surveyed, Te Toi was the only island in the Cavalli Group on which this fern was found. A flora of 53 taxa was recorded.

FERNS Phormium tenax Notodanthonia biannularis Adiantum hispidulum Pseudopanax lessonii N. unarede Asplenium flaccidum LIANE Parapholis incurva * subsp. haurakiense Muehlenbeckia complexa Paspalum dilatatum* A. lucidum GRASSES Poa seticulmis A. obtusatum subsp. Agropyron kirkii Sporobolus africanus* northlandicum Aira caryophyllea* Vulpia bromoides* Pteridium aquilinum Anthoxanthum odoratum* MONOCOT HERBS var. esculentum A vena fatua* Arthropodium cirratum TREES AND SHRUBS Bothriochloa macra* Astelia banksii Coprosma macrocarpa Briza minor* Scirpus nodosus C. repens Bromus mollis* DICOT HERBS Cyathodes fasciculata Catapodium rigidum * Anagallis arvensis* Geniostoma ligustrifolium Chionochloa bromoides Centaurium erythraea* Hebe stricta var. stricta Dichelachne crinita Cyathodes fraseri Leptospermum scoparium D. micrantha Dichondra repens Metrosideros excelsa Microlaena stipoides Disphyma australe 95 Geranium sp. (unnamed) Oxalis corniculata Senecio lautus Gnaphalium luteo-album Plantago lanceolata* Silene gallica* Hypochoeris radicata* Polycarpon tetraphyllum* Tetragonia trigyna Linum trigynum Samolus repens Trifolium dubium*

Tuturuowai A landing was made on the southern end of this very steep, small island. It was obvious that the island had at some stage been scaled as a rope hung over the most difficult part of the route. However, the rope broke when tested and so I did not reach the summit. Due to the difficulty of access and general steepness, the island did not appear to have been modified in any significant way. The summit appeared to be crowned in fairly dense pohutukawa and houpara forest, although other species were almost certainly present. Large tufts of Chionochloa were prominent on the steep spurs leading up to the summit. A flora of 29 taxa was recorded from the lower southern slopes.

FERNS Aira multiculmis* Apium australe Asplenium flaccidum A vena fatua* Dichondra repens subsp. haurakiense Bromus mollis * Disphyma australe A. lucidum Chionochloa bromoides Hypochoeris radicata* TREES AND SHRUBS Deyeuxia billardieri Lobelia anceps Coprosma repens Poa anceps Polycarpon tetraphyllum* Hymenanthera novae- Sporobolus africanus* Rhagodia triandra zelandiae MONOCOT HERBS Salicornia australis Metrosideros excelsa Arthropodium cirratum Samolus repens Pittosporum crassifolium Astelia bank si i Senecio lautus Pseudopanax lessonii Scirpus nodosus Stellaria media* GRASSES DICOT HERBS Tetragonia trigyna

Whatapuke (Fig. 2) This island had been grazed by cattle in the past and was still largely grassed. The slightly sloping summit plateau showed the most advanced regeneration with bracken taking over the grassland. The slopes down to the northern coast were clothed in meadow rice grass dominant grassland, with tangles of wire vine and Calystegia tugoriorum. Large clumps of N.Z. flax and Cyperus had established and small concentrations of paspalum, cocksfoot and wild oats occurred. Right on the coastline were dense areas of barley grass (Hordeum murinum). On the very steep grassy slopes forming the south side of the island, col• onies of N.Z. flax, Doodia, Adiantum cunninghamii and kiokio (Blechnum capense) were developing. A large but discrete patch of gorse existed on the south-west slopes. A flora of 81 taxa was recorded.

96 FERNS Bromus mollis* Cakile mart tima* Adiantum cunninghamii B. unioloides* Centaurium erythraea* Blechnum capense Catapodium rigidum* Centella uniflora Doodia media Chionochloa bromoides Cerastium glomeratum* Pteridium aquilinum Cynodon dactylon* Crepis capillaris* var. esculentum Dactylis glomerata* Cyathodes fraseri Pyrrosia serpens Deyeuxia billardieri Dichondra repens TREES AND SHRUBS Dichelachne crinita Disphyma australe Cassinia retorta Hordeum murinum* Erigeron floribundus* Coprosma repens Lagurus ovatus* Geranium sp. (unnamed) Cordyline australis Microlaena stipoides Hypochoeris radicata* Geniostoma ligustrifolium Notodanthonia biannularis Lobelia anceps Hymenanthera novae- Parapholis incurva* Medicago lupulina * zelandiae Paspalum dilatatum* M. polymorpha* Leptospermum scoparium Pou anceps Melilotus indica* Metrosideros excelsa Spinifex hirsutus Oxalis corniculata Phormium tenax Sporobolus africanus* Plantago lanceolata* Pimelea prostrata Vulpia bromoides* Polycarpon tetraphyllum * Ulex europaeus* MONOCOT HERBS Raphanus raphanistrum * LIANES Arthropodium cirratum Rumex crispus* Calystegia septum Astelia banksii Sagina procumbens* C. tugoriorum Carex pumila Salicornia australis Muehlenbeckia complexa C. flagellifera Salsola kali* GRASSES Cyperus ustulatus Samolus repens Agropyron kirkii Juncus gregiflorus Silene gallica* Solanum nigrum* Aira caryophyllea * Scirpus cernuus Sonchus oleraceus* A. multiculmis* Scirpus nodosus Trifolium dubium* Anthoxanthum odoratum* Thelymitra longifolia T. glomeratum* Arena fatua* DICOT HERBS Briza minor* Anagallis arvensis*

Whatapukeiti Rocks 5 or 6 lightly vegetated rocks lay between Whatapuke and Tarawera Islands (Fig. 2). Most were devoid of vegetation on their northern faces which were exposed to the heaviest seas. The largest had a good vegetation cover on its south side with a more or less continuous cover of N.Z. flax, Chionochloa and renga lily with occa• sional wharawhara. The summit ridge supported N.Z. broom, Scirpus nodosus, patotara and rare taupata. Most of the rocks supported a small flora of salt-tolerant plants such as glasswort, N.Z. iceplant and spurrey. A total flora of 36 taxa was recorded from all the rocks.

FERNS Phormium tenax Chionochloa bromoides Asplenium flaccidum Pseudopanax lessonii Deyeuxia billardieri subsp. haurakiense L1ANE Notodanthonia biannularis Pteridium aquilinum Muehlenbeckia complexa N. racemosa var. esculentum GRASSES Parapholis incurva* TREES AND SHRUBS Anthoxanthum odoratum* Poa anceps Carmichaelia aligera A vena fatua * Sporobolus africanus * Coprosma repens Bromus unioloides* Vulpia bromoides*

97 MONOCOT HERBS Anagallis arvensis* Salicornia australis Arthropodium cirratum Cyathodes fraseri Samolus repens Astelia banksii Disphyma australe Senecio lautus Carex breviculmis Erigeron floribundus * Solanum nigrum* Scirpus nodosus lobelia anceps Sonchus oleraceus* Thelymitra longifolia Polycarpon tetraphyllum * Spergularia marginata DICOT HERBS Sagina procumbens*

DISCUSSION

The small size and high degree of exposure of most of the islands and rocks has led to the widespread development of extremely salt-tolerant mat- plant communities. These are dominated by N.Z. iceplant and taupata. The visually dominant plant of coastal areas in the Cavalli Island Group is undoubtedly Chionochloa bromoides. Its prominence is attested by the fact that it is the only plant collected by all four of the visitors mentioned under the Previous Work section. It appears likely that totara will become an important element in the vegetation of the southern islands in particular. Young trees, presumably from bird-introduced seed, were found in substantial numbers on the sum• mits of six islands. The four main groups of islands all display some different characteristics. The eastern group are clearly the least disturbed, and the relatively small, dominantly indigenous floras reflect this. The southern group have for the most part undergone gross modification through grazing, and this is reflected in a depauperate native flora and a corresponding increase in adventives, particularly noxious weeds. The northern group of islands, although generally greatly modified in the past, have been allowed to regenerate for a longer period than the southern group, possibly due to less easy access. Thus small pockets of primarily native species have established, which will provide a suitable habitat for further native introductions (e.g. by birds) and serve as a seed source for the spread of native communities over the islands. The last of the four groups, the small islands lying close to Motukawanui, are most notable for their relatively large floras in relation to their size. This can be attributed to the shelter provided by Motukawanui.

Noxious weed control 5 species are considered a nuisance to visitors and/or a threat to indigenous vegetation. Prickly hakea is present on the summits of Haraweka and Motumuka Islands, and is still at an eradicable level. Gorse is fairly widespread on Kahangaro, Motukawaiti, Whatapuke and Piraunui Islands, and could be controlled by spraying on the three former islands with minimal impact on native vegetation as these islands are largely grassed. The particularly badly infested western slopes of Piraunui could be similarly treated. Blackberry on Kahangaro and Motukawaiti could be con- 98 trolled in a similar manner; however, more care would be needed on Haraweka with its Hibiscus population. Sodom's apple could be manually cut out on Kahangaro, Motukawaiti and Motumahanga Islands. The last threat lies in kikuyu grass. Fragments were found washed up on Panaki Island, and both the mainland and Motukawanui provide abundant sources of this troublesome grass. It has frequently been observed to have a deleterious effect on indigenous herblands and grasslands, eventually com• pletely obliterating them. Further, regeneration of any native vegetation through the dense kikuyu sward is virtually impossible. Regular checks for new introductions and immediate spot control are advocated.

Rare plant management The outstanding rare plant of the group is the native Hibiscus trionum. It was found only in small numbers on Motukawaiti and Nukutanga Islands and action is probably not warranted in these cases. However, the plant is abundant on the northern slopes of Haraweka Island in low herb- and grassland. Regeneration is obviously occurring quickly on this island and consideration should be given to maintaining cleared areas as a habitat for this species. Adams (1969) recorded Hibiscus from Motutapere and Whatapuke Islands, though plants could not be located during the present survey. If future investigations show Hibiscus to be present on these islands, maintenance of cleared areas may be required there also.

Reservation priorities The whole of the eastern group and Motutakupu would be top priority for reservation for scientific purposes from both floral and faunal points of view. Of the remaining islands, Nukutaunga (including the nearby Tuturuowai) exhibits the best regeneration of coastal forest cover. In addi• tion both these islands are relatively inaccessible, providing some security as a wildlife and plant refuge. Haraweka should be reserved on account of the large Hibiscus population. The eastern part of Hamaruru Island also exhibits some areas of good regeneration and is next priority for reserva• tion. All of the islands lying close to Motukawanui should be afforded reserve status as they are (particularly from an archaeological point of view) an integral part of this large island. In general, the depleted, grossly modified southern islands are most suitable for heavy visitor pressure (i.e. as recreation reserves) while the less accessible eastern and northern islands would provide better flora and fauna reserves.

ACKNOWLEDGEMENTS

I would like to thank all other members of the Group for their companionship; especially Roger Grace for patient and skilful landings on numerous islands and rocks, and Dave Court for additions to the lists from Hamaruru, Panaki and Motukaroro Islands. Dr E. Edgar kindly identified three species of Carex. 99 REFERENCES

Adams, CP. 1969: Cavalli Island Survey. Unpublished Report 12/5/14, Department of Inter• nal Affairs, Wellington. Allan, H.H. 1961: "Flora of New Zealand. Volume 1." Government Printer, Wellington, 1085p. Court, D.J. in prep: The spread of teatree (Leptospermum) scrub on Motukawanui Island, Cavalli Group, northern New Zealand. Dickson, E.M. 1973: Stephenson's Island, Whangaroa and Motukawanui, Cavalli Islands. Unpublished report to Lands and Survey Department, Auckland. Hayward, B.W. 1979: Cavalli Islands trip, New Year 1978-1979. Introduction and Acknow• ledgements. Tane 25: (this issue). Hayward, B.W. & Hayward, G.C. 1979: Lichens of the Cavalli Islands, northern New Zealand. Tane 25: (this issue). Hayward, B.W, Moore, P.R., Puch, G.F., Ramsay, E.G. & Wright, A.E. 1979: Archaeo• logical sites on the Cavalli Islands, northern New Zealand. Tane 25: (this issue). Moore, L.B. & Edgar, E. 1970: "Flora of New Zealand. Volume 2". Government Printer, Wellington. 354p. New Zealand Weed and Pest Control Society 1969: "Standard common names for weeds in New Zealand". Editorial Services, Wellington. 141 p. Olsen, K.P. 1976: Notes on the flora of Motukawanui Island (Cavalli Group). Unpublished report to Commissioner of Crown Lands, Auckland. Wright, A.E. 1977: Vegetation and Flora of the Moturoa Island Group, Northland, New Zealand. Tane 23: 11-29. Wright, A.E. 1979: Vascular flora of Motukawanui Island, Cavalli Group, northern New Zealand. Tane 25: (this issue).

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