Kunzea robusta de Lange et Toelken, 2014

de Lange, Peter J., 2014, A revision of the New Zealand Kunzea ericoides (Myrtaceae) complex, PhytoKeys 40, pp. 1-185 : 85-96

10. Kunzea robusta de Lange et Toelken sp. nov.

A K. ericoides (A. Rich.) Joy Thomps. habitu heterophyllo, indumento in ramulis adultis persistenti sericeo abundanti plerumque antrorso-appresso raro interdum pilis divergentibus, fructibus late obconicis vel turbinatis raro cupulatis plerumque pubescentibus differt. Etiam propriis chromosomatibus recedit.

Holotype

(Fig. 52). New Zealand, North Island, Raukumara Ecological Region, Motu Ecological District, above Papatea Bay, 37°40'S, 177°50'E, 60 m a.s.l. 'On road side cliff face growing on heavily eroded clay overlying fractured greywacke’. P. J. de Lange 4647, 22 Oct 2004, AK 288521! Isotype AD! CHR!

Etymology.

The specific epithet robusta alludes to the stature of mature trees of this species which can, under stable conditions, attain 30 m tall and trunks of up to 1 m d.b.h.

Description

(Figs 53, 54, 55, 56, 57, 58). Growth habit trees (8-)20-25(-30) m tall, rarely decumbent shrubs up to 1 × 3 m; trees, depending on local conditions, mostly forming broad spreading canopies; in exposed situations branching at or close to the trunk base, while those growing in dense stands or sheltered sites usually with the lower 50-75% of the trunk devoid of branches. Trunk 1(-6) erect, 0.10-0.65(-1.0) m d.b.h.; mature trees usually devoid of branches for at least the first 1-3 m, basal portion of trunks covered with firm to semi-detached, stringy to coarsely tessellated, corky-coriaceous bark. Bark early bark subcoriaceous, grey-brown, cinnamon brown or dark brown, elongate, usually bearing deep transverse cracks (especially on branch flanges and decurrent leaf bases) otherwise firmly attached, margins elongate, sinuous, ± entire with scarcely any flaking; old bark either stringy, or coarsely tessellated, mostly corky-coriaceous, though in dense forest stands tending toward subcoriaceous or chartaceous, firmly attached above, detaching basally, often hanging semidetached; peeling upwards along trunk in narrow to broad, tabular strips up to 4 m long, margins ± entire to weakly irregular, usually straight; upper surface either ± smooth with coarsely tessellated but firm upper surface, or deeply and longitudinally corrugated and cracked (rarely peeling); early bark flakes usually crumbling in hand, old bark strips firm and not crumbling, snapping with a ± entire margin. Branches initially arising from or close to trunk base; these initial branches progressively dying, such that branches are increasingly confined to the upper 50-75% of trunk. Branches weakly flexuose or not, initially erect, soon arching outwards and spreading with distal ends mostly erect, rarely with whole branch or distal portion completely pendulous; branchlets numerous, slender, clustered toward branch ends, ± quadrangular to subterete, with leaves ± evenly spaced along length or in exposed situations, crowded toward apices; branchlets sericeous, indumentum copious, hairs hyaline to translucent (appearing white when young, maturing grey); mostly either long or short antrorse-appressed; if long, then usually weakly flexuose hairs 0.15-0.20(-0.38) mm long; if short, not flexuose, 0.09-0.15 mm long. In eastern Coromandel Peninsula and coastal East Cape to near Mahia Peninsula, branchlet indumentum in mixtures of mainly short (0.03-)0.05(-0.08) mm long divergent hairs, and sparse, 0.1-0.2 mm long, antrorse-appressed hairs (see Fig. 57A-D). In the Rangitikei region, seedling and juvenile plants up to 2 m tall have branchlet hairs mostly divergent, short (0.04-)0.08(-0.10) μm long. Vegetative buds conspicuous; at resting stage 0.3-2.8 mm diam., ovoid to broadly ellipsoid; scales scarious, deciduous or persistent, 0.6-0.8(-1.4) mm long, amber, red-brown to wine-red, basally broadly ovate, grading through ovate-deltoid to broadly lanceolate, cuspidate; midrib prominent, strongly keeled, prolonged to short cuspidate tip, lateral veins absent, colliculate, with oil glands, scattered, colourless, drying the same colour as the scale body, apical scale margins, keel, and keel apex copiously covered in long, white, sericeous hairs. Leaves with distinct juvenile and adult forms, sessile to shortly petiolate, well spaced to crowded along branchlets, spreading, suberect to patent, flat to weakly recurved in apical 30-50%, light green or dark green above, paler beneath; oblanceolate, broadly oblanceolate, broadly lanceolate, lanceolate to linear-lanceolate, rarely elliptic to obovate; apex subacute to acute, rarely obtuse, rostrate or shortly apiculate, base attenuate to narrowly attenuate; adaxial surface flat, weakly convex to slightly v-shaped; oil glands up to 600, evident when fresh, becoming more conspicuous when dry, midrib very slightly raised near base, otherwise not evident for rest of length, leaf base finely covered in antrorse-appressed, silky hairs, glabrate; abaxial surface slightly concave to flat or v-shaped in apical recurved portion otherwise weakly concave, finely glandular punctate, oil glands abundant up to 500, more evident when dry; midrib slightly raised for entire length, prolonged slightly at apex, hairs as for adaxial surface; lamina margin initially finely covered with a thin often interrupted band of 0.2-0.8 mm long, flexuose, spreading to antrorse-appressed hairs not or rarely meeting at apex; hairs mostly shedding with age, usually with only the basal portion ± retained. Lamina of juvenile plants from mainly coastal areas and northern North Island (14.6-)19.0(-28.4) × (1.6-)2.2(-2.5) mm; from inland areas, especially the Rangitikei, central and northern Wairarapa and Mt Egmont, (3.2-)4.6(-6.3) × (0.7-)1.2(-1.5) mm; adult lamina of plants from mainly coastal areas and northern North Island (4.9-)14.2(-20.1) × (0.9-)1.7(-3.0) mm; from inland areas, especially from the central North Island, Rangitikei, Wairarapa, and Central Otago (5.8-)9.3(-12.3) × (1.2-)1.8(-2.2). Perules usually very conspicuous, rarely obscured by surrounding leaves; at resting stage 1.9-3.0 mm diam., broad ovoid, ovoid, narrow-ovoid to broadly ellipsoid, squamiform; scales scarious, persistent, 0.6-1.0(-1.6) mm long, red-brown to red, basally broadly ovate, grading through ovate-deltoid to broadly lanceolate, cuspidate; midrib prominent, becoming even more on old or dried specimens, strongly keeled, prolonged to a short cuspidate tip (this becoming more obvious on drying), lateral veins absent, colliculate, with oil glands, scattered, colourless, drying the same colour as the scale body, upper scale margins, keel, and keel apex copiously covered in long, white, silky hairs. Inflorescence mostly a compact corymbiform to shortly elongate (1-)12(-30)-flowered botryum up to 60 mm long; usually on brachyblasts with the terminal shoot corymbiform or extending toward the end of the flowering season as a slightly longer (up to 80 mm long) 4-12-flowered, elongate botryum; flowers usually crowded, terminal portion usually bearing undeveloped flowers and dormant vegetative bud or active vegetative growth. Inflorescence axis densely invested with short, spreading to antrorse-appressed silky hairs. Pherophylls deciduous or more or less persistent; squamiform grading into foliose; squamiform pherophylls tightly clasping pedicels, 0.4-1.2 × 0.3-0.6 mm, red-brown to brown, broadly to narrowly deltoid or lanceolate, apex acute, subacute to obtuse, weakly keeled, upper keel and margins finely ciliate; foliose pherophylls spreading, flat or weakly recurved, (6.0-)9.0(-17.9) × (1.1-)1.2(-1.8) mm, green, elliptic, oblanceolate, broadly lanceolate to lanceolate, apex obtuse, cuspidate, base attenuate; adaxial surface usually convex to weakly v-shaped, oil glands 10-30(-50), midrib slightly raised near base, evident for rest of length, basally covered in sparse to dense, antrorse-appressed, silky hairs; abaxial surface flat or weakly convex, glandular punctate, oil glands 20-40; midrib raised for most of length, densely covered in antrorse-appressed, silky hairs to apex, lamina margin obscured by dense covering of antrorse-appressed hairs. Pedicels (1.2-)3.8(-5.2) mm long at anthesis, usually elongating slightly after anthesis, terete, sparsely to densely invested in antrorse-appressed, weakly flexuose, silky hairs. Flower buds pyriform to obconic, apex flat or weakly domed prior to bud burst; calyx valves not meeting. Fresh flowers when fully expanded (4.3-)7.7(-12.0) mm diam., usually reducing in size toward end of flowering season. Hypanthium (2.1-)3.1(-4.1) × (3.0-)3.9(-5.2) mm, with free portion 0.4-0.9 mm long, dark green or red-green, drying green-brown or red-brown; mostly broadly obconic to turbinate, sometimes cupular, terminating in dark-green to red-green coriaceous rim bearing five persistent calyx lobes. Hypanthium surface when fresh faintly ribbed and sparingly dotted with pink or colourless oil glands, these drying dull yellow-brown or brown; either finely pubescent with the ribs and veins conspicuously covered in longer silky, antrorse-appressed hairs, or glabrous; hypanthium similar when dry though with the ribs more strongly defined and clearly leading up to calyx lobes. Calyx lobes 5, persistent, mostly spreading, coriaceous, (0.52-)0.83(-1.1) × (0.60-)0.90(-1.4) mm, pale green to red-green, broadly ovate, ovate-truncate to broadly obtuse, weakly keeled, external face of keel usually obscured by a broad band of antrorse-appressed, silky, white hairs, otherwise glabrous; margins white or pale green often flushed pink, surface somewhat sparsely glandular punctate, oil glands ± colourless when fresh drying dark yellow to yellow-brown, otherwise glabrate. Receptacle green or pink at anthesis, consistently darkening to crimson after fertilisation. Petals 5(-6), (1.5-)2.6(-3.8) × (1.3-)2.6(-3.6) mm, white, rarely pink (sometimes drying pale yellow or cream), spreading, orbicular, suborbicular to ovate, apex rounded to obtuse, margins ± finely and irregularly denticulate or crimped 1-6 or more times, rarely entire, oil glands colourless, drying opaque or grey. Stamens (15-)33(-58) in 2 weakly defined whorls, arising from receptacular rim, filaments white. Antipetalous stamens 3-5(-6) sometimes petaloid, antisepalous stamens (3-)5(-8). Outermost antipetalous stamens usually outcurved, sometimes weakly incurved or in mixtures of both on filaments 1.5-4.6(-5) mm long, inner stamens usually at the base of the outermost antipetalous pair (0.8-)2.3-3.1 mm, weakly incurved. Antisepalous stamens mostly shorter than outermost antipetalous stamens, sometimes of comparable length, generally 0.6-1.2 mm, weakly to strongly incurved, very rarely a few outcurved. Anthers dorsifixed, 0.38-0.63 × 0.18-0.32 mm, ellipsoid to ovoid-ellipsoid or deltoid, latrorse. Pollen white (9.1-)14.7(-15.1) μm. Anther connective gland prominent, light pink, salmon pink, yellow to orange when fresh, drying dark orange, orange-brown or dark brown, spheroidal, finely rugulose or papillate. Ovary 5(-6) locular, each with 15-26(-36) ovules in two rows on each placental lobe. Style 2.0-2.5(-3.5) mm long at anthesis, elongating slightly after anthesis, white or pinkish-white; stigma broadly capitate, at least 1.5 × style diam., flat, greenish-white or pale pink, flushing red after anthesis, surface finely granular-papillate. Fruits mostly all falling within 1-2 months of seed dehiscence, but a few long persistent, (2.2-)3.8(-4.6) × (3.2-)4.0(-5.3) mm, initially dark green to chesnut-brown fading with age to greyish white, obconic, broadly obconic to ± turbinate, rarely cupular; veins and ribs ± conspicuous on drying; external surface distinctly hairy, very rarely glabrescent or glabrous; hairs short to long antrorse-appressed; calyx valves incurved, splits concealed by dried, erect, free portion of hypanthium. Seeds 0.9-1.0(-1.1) × 0.35-0.40(-0.48) mm, oblong, oblong-obovate, oblong-elliptic, curved near apex, laterally compressed, 2-3-angled with convex to flattened faces, apex rounded to subacute, base oblique, ± flattened; testa semi-glossy, orange-brown to dark brown, surface coarsely reticulate. FL: (Aug-)Nov-Jan-Feb(-Jun). FT: (Jul-)Feb-Apr(-May). Chromosome Number n = 11II, 2 n = 22, 23 (see de Lange and Murray 2004).

Representative specimens

(620 sheets seen). New Zealand (North Island). Mangamuka Gorge Scenic Reserve, P. J. de Lange 4138, 17 Jan 2000, (AK 287965); Maropiu, Omamari Road, Te Kawa Stream, P. J. de Lange 4202 & L. J. Forester, 21 Jan 2000, (AK 288034, Duplicate: AD); Pakiri, Rahuikiri Beach Road, P. J. de Lange 5532 & G. M. Crowcroft, 5 Oct 2002, (AK 283235); Ponui Island, unnamed stream draining south to Motunau Bay, P. J. de Lange 6688 & E. K. Cameron, 16 Oct 2005, (AK 297493), Auckland City, Western Springs, P. J. de Lange 4619 & M. A. Crowcroft, 30 Oct 2000, (AK 288078, Duplicate: AD); Mauku, Bald Hills, Manukau, H. Carse s.n., 15 Nov 1901, (CHR 296314); Coromandel Peninsula, Moehau Range, Little Moehau, P. J. de Lange 4742, 2 Dec 2000, (AK 287038, Duplicate: AD); Whangamarino, Falls Road, P. J. de Lange 4015, 23 Nov 1999, (AK 242673); Hamilton City, Waikato River, Delamere Street, P. J. de Lange 1195, 6 Jan 1992, (AK 207191, Duplicates: AD, BISH, CHR, HO); Te Kauri Scenic Reserve, Waikuku Valley, Devlin Track, P. J. de Lange 4265 & P. de Lange, 29 Jan 2000, (AK 286134, Duplicates: AD, NSW); Kohioawa Beach, Ohinekoao Cliffs, P. J. de Lange 5325, 25 Oct 2001, AK 287041 (Duplicates: AD, HO); Whirinaki Forest, Arohaki Lagoon, southern end, P. J. de Lange 6690 & P. B. Cashmore, 15 Mar 2006, (AK 297496); Taupo, Rotongaio, R. H. Steele s.n., 7 Feb 1964, (WELTU 3048); 3 km east of Matiere, P. J. de Lange 4337, 31 Jul 2000, (AK 286126, Duplicates: AD, MEL); Mt Egmont National Park, Mt Taranaki/Egmont, Dawson Falls (Manaia Road End), J. Clarkson s.n. & S. Caldwell, 26 Jan 2007, (AK 298312, Duplicate: AD, CHR, MEL, NSW, WELT); Lottin Point Road, Otanga, P. J. de Lange 4649, 8 Nov 2000, (AK 288520, Duplicates: AD, MSC, P, WAIK); Gisborne Plains, Mangaoporo River, P. J. de Lange 4653, 8 Nov 2000, (AK 286067, Duplicate: AD, WELT); Mahia Peninsula, Whangawehi Stream, P. J. de Lange 4660, 9 Nov 2000, (AK 286161, Duplicate: AD); Hawke’s Bay, Tangoio, Te Ngaru Stream, P. J. de Lange 4670, 9 Nov 2000, (AK 286251, Duplicate: AD, CHR); 4 km southwest of Horopito, above Makotuku River, P. J. de Lange 4245 & N. J. D. Singers, 27 Jan 2000, (AK 288038, Duplicate: AD); Kawhatau River, Kawhatau Valley Road, P. J. de Lange 4379, 10 Aug 2000, (AK 288076, Duplicate: AD); Whangaehu River Mouth, Whitiau Scientific Reserve, C. C. Ogle 4887 & A. Dijkgraaf, 15 Dec 2004, (AK 297361); east of Puketoi Range, Waihoke, A. P. Druce s.n., Dec 1973, (CHR 273332); eastern Wairarapa, 3 km west of Whakataki, P. J. de Lange 649 & G. M. Crowcroft, 9 Jan 1991, (AK 202104, Duplicate; AD); Upper Hutt, Trentham, W. M. Fleming s.n., 6 Jan 1965, (WELTU 17697). Poor Knights Islands. Tawhiti Rahi, near Puketuaho, G. R. Parrish s.n., 18 Sep 2006, (AK 297487, Duplicate: AD). Mokohinau Islands. Motukino (Fanal Island), E. K. Cameron 7717 & P. J. de Lange, 15 Sep 1994, (AK 226069); Hauturu (Little Barrier Island). Te Maraeroa, J. P. Burrell s.n., Dec 1962, (OTA 7350). Aotea (Great Barrier Island). Whangaparapara Road, near Stamping Battery Remains, P. J. de Lange 4546 & G. M. Crowcroft, 8 Oct 2000, (AK 251367, Duplicate: AD). New Zealand (South Island). Wangapeka Valley, R. Mason s.n., 22 Dec 1946, (CHR 58115); Fairdown, P. J. de Lange 4783 & P. I. Knightbridge, 4 Dec 2000, (AK 288488, Duplicate: CHR); D'Urville Island, Catherine Cove, Kiangawari, Pylon Track, P. J. de Lange 5057 & G. M. Crowcroft, 19 Jan 2001, (AK 288511, Duplicate: AD); Queen Charlotte Sound, Green Bay, P. B. Heenan s.n., 8 Jan 2004, (CHR 569892); Rarangi - Golf Links Road, P. J. de Lange 5115, 23 Jan 2001, (AK 288571, Duplicate: AD); Waima (Ure) River, Ure Road, P. J. de Lange 5448 & G. M. Crowcroft, 4 Nov 2001, (AK 286221); Motunau Settlement Road, Water Supply Creek, QE II Covenant, P. J. de Lange 5104, 21 Jan 2001, (AK 288517) (Duplicate: AD); Port Levy, Banks Peninsula, B. H. Macmillan 66/4, 1 Jan 1966, (CHR 166497); Grey River, Atarau Road, P. J. de Lange 4809 & P. I. Knightbridge, 8 Dec 2000, (AK 288289, Duplicates: AD); Old Christchurch Road, nr Okuku Reservoir, Kawhaka Road, P. J. de Lange 4811 & P. I. Knightbridge, 8 Dec 2000, (AK 288288, Duplicates: AD, CHR, HO); Lake Wanaka, T. Kirk 957, 6 Jan 1877, (WELT SP029439); Trotters Gorge, P. B. Heenan s.n., 9 Jan 2003, (CHR 567749); Otago Peninsula, Pikikaretu Beach, J. P. Burrell K25, 21 Mar 1962, (OTA 7376); Taieri River Mouth, J. P. Burrell K23, 6 Feb 1962, (OTA 7370); Dunstan Mountains, Bendigo, J. P. Burrell s.n., 26 Dec 1961, (OTA 7362); Roxburgh Dam, near Chasm, L. B. Moore s.n., 17 Dec 1969, (CHR 132250); Queensberry, A. P. Druce APD1388, Jan 1992, (CHR 471980); Clutha River, South of Balclutha, J. P. Burrell K15, 14 Feb 1962, (OTA 7367).

Distribution

(Fig. 59). Endemic. New Zealand, North and South Islands (sea level - 1000 m a.s.l.). In the North Island widespread with the exception of Te Paki and the sand tombolo of Te Aupouri. Scarce in Taranaki, from where de Lange (2006) (treated there as Kunzea aff. ericoides (B)) had erroneously stated that the species was absent from Mt Taranaki/Egmont because at that time the populations of Kunzea on that mountain were believed to represent another allied, but potentially distinct, species, Kunzea aff. ericoides (f) (see de Lange and Murray 2004; de Lange et al. 2005). In the southern one-third of the North Island, it appears to be absent from Kapiti Island from where only Kunzea amathicola has thus far been collected. In the South Island, Kunzea robusta , although wide ranging, is often absent over large parts of seemingly suitable habit. It is also naturally absent from most of north and south-west Nelson where it is replaced by Kunzea ericoides and, in the extreme north-west, Kunzea amathicola . However, occasional trees and stands grow near Wangapeka and in places along the Buller River. It was also planted around Totaranui, Abel Tasman National Park from where it began to naturalise.Those plantings have now been eradicated. On the West Coast, in an area centred on Fairdown, Westport, and Cape Foulwind and also within the lower Grey River catchment, Kunzea robusta is locally abundant. It also grows to the west of the main divide along the upper Ahaura River, below Mt Ranunculus, and on the foothills of the Alexandra Range. South of here, Kunzea robusta is scarce with only isolated, mainly roadside stands present near Kumara and Hokitika. The close association of these stands to roadsides suggests that the stands may not be natural, or that the species has benefited from the frequent disturbance caused by road construction and ongoing maintenance. Occasional trees of this species have also been collected from Okarito (e.g., B. H. Macmillian 97/22 & E. H. Woods (CHR 512939)) where they occur as planted specimens and from which source it is now naturalising. In the eastern South Island this species is more widespread, though initially strictly as a coastal and lowland tree of the Marlborough Sounds south to about North Canterbury. In North Canterbury, Kunzea robusta occasionally extends well inland up the river valleys where it is sympatric with and eventually replaced by Kunzea serotina . South of there, on Banks Peninsula, Kunzea robusta seems to be the only species present, while on the adjacent Canterbury Plains it is completely replaced by Kunzea serotina until, on the slightly more elevated foothills of south Canterbury, Kunzea robusta reappears as a local dominant. In north-eastern Otago, Kunzea robusta is common around Trotters Gorge and the Horse Range but south of here it has an otherwise mainly coastal distribution, reaching its greatest abundance around Dunedin and on the adjacent Otago Peninsula. A few inland locations are known, especially around Lakes Hawea and Wanaka, where the species is sympatric with Kunzea serotina . Kunzea robusta is also common along the northern and eastern foothills of the Dunstan Range south of which it occurs only very locally, in isolated patches along the Clutha River as far south as Kaitangata and Balclutha. These southerly outliers are not only the southern limit for the species but also for the genus worldwide.

Recognition.

The potential distinctiveness of Kunzea robusta was first recognised in New Zealand by William Colenso (1811-1899) who collected specimens of it from the Pahawa [Pahaoa] River, eastern Wairarapa (W. Colenso 2011, (WELT SP022862, Duplicate: K). Obviously impressed by its sturdy habit, Colenso regarded it as a new species for which he proposed the name "Leptospermum pahawaense" to J. D. Hooker. However, Hooker never took up the name ( Hooker 1867). In hindsight it is intriguing that New Zealand botanists have failed to recognise that Kunzea robusta is distinct from Kunzea ericoides . It would seem that this has come about for two main reasons. Firstly, because the type of Leptospermum ericoides (≡ Kunzea ericoides ) was lodged in an overseas herbarium (P), where it was not easily accessible to New Zealand-based botanists, and so until now had not been critically examined. Secondly, Kunzea robusta is the most common of the Kunzea ericoides complex, and, in the absence of a critical evaluation of the type, it is understandable that New Zealand botanists have come to assume that this common tree was the one described by Richard (1832). Even so, recourse to Richard’s protologue does provide a very clear description of Kunzea ericoides sens. str., which should have enabled the recognition of Kunzea robusta long before now. For example, Richard clearly stated that Leptospermum ericoides (≡ Kunzea ericoides ) had glabrous stems, and leaves (except for the leaf margins), glabrous pedicels, glabrescent calyces and capsules. Even allowing for the fact that Kunzea ericoides does have minute hairs on its branches, they are so small and sparingly distributed that they are easily missed, so Richard’s use of ‘glabrous’ in that context makes sense. Irrespective, any Kunzea with conspicuously hairy stems, leaves, pedicels and fruits could not fit Richard’s species. Despite this, and probably because it was so widespread and common, Kunzea robusta remained unrecognised, ironically ended up serving as the 'type species’ from which Thomas Kirk and George Simpson segregated their Leptospermum ericoides var. lineare (≡ Kunzea linearis ), Leptospermum sinclairii (≡ Kunzea sinclairii ) and Leptospermum ericoides var. microflora (≡ Kunzea tenuicaulis ).

As circumscribed here, Kunzea robusta remains a very variable species. It is primarily a coastal to lowland, rarely montane, arborescent species (Fig. 58A-G), which normally reaches heights of between 20-25 m tall, and 0.65 m d.b.h. (Fig. 58B, C). Occasional trees attaining heights of up to 30 m, and trunks up to 1 m d.b.h. are known from the North Island (Northland, Aotea (Great Barrier Island) and the eastern Wairarapa), making this species the largest and tallest in the genus (Fig. 58B-D). The bark of Kunzea robusta is typically extremely coriaceous, and is characteristically shed in long tabular strips up to 4 m long (Fig. 58H-M) that often hang in a loose skirt around the trunk. The upper surface of these strips is usually intact, with little secondary peeling (Fig. 58M), though trees growing in heavy shade, or wetter than usual conditions may have thinner, subcoriaceous bark, and some secondary peeling. The adult branchlet indumentum of Kunzea robusta , for most of its range, consists of antrorse-appressed, silky hairs (Fig. 55A-C), though hair length can be extremely variable. As a rule, Kunzea robusta gathered from montane situations, and from the drier eastern side of both islands, tend to have shorter hairs, which may require a hand lens of at least 10 × magnification to see, while those from the northern half of the North Island, Marlborough Sounds, Banks Peninsula and Dunedin, particularly specimens growing in coastal to lowland sites, tend to have visibly longer antrorse-appressed branchlet hairs (Fig. 55A-C). Nevertheless, despite these geographic generalisations, it is not uncommon for two trees growing side by side to have either short or long hairs. The mature leaves of this species, though variable in size and shape (Fig. 54L, M, P-Q), are unified in being consistently glabrate with the lamina margin and abaxial midrib sparsely to conspicuously silky hairy (Fig. 54N-O), with the hairs only very rarely meeting at the leaf apex (Fig. 54O). The adaxial and abaxial leaf surfaces of Kunzea robusta are conspicuously glandular punctate (Fig. 54L-M), with the adaxial surface characteristically dull rather than glossy green. Kunzea robusta has extremely variable pherophylls both within and between populations. These range from squamiform to foliose, with either one or both types found on any particular individual. Irrespective of type, they are almost always shed during flowering. However, in some populations the foliose pherophylls are retained below some (but not all) flowers, and in these cases the pherophylls of any particular individual can range from elliptic, through oblanceolate, to broadly lanceolate or lanceolate. The inflorescence of Kunzea robusta is initially corymbiform, and in most places (see below for exceptions) this changes toward the end of the initial flowering through activation of the terminal vegetative bud (Fig. 53A). The subsequent vegetative growth partially elongates the initial inflorescence, and so in this species (more than any other of the species possessing an initially corymbiform botryum) the vegetative growth usually progresses into a further late season flowering as a distinctively elongated botryum. However, in the eastern Coromandel Peninsula and in coastal sites from East Cape south to the sand tombolo connecting Mahia Peninsula to the mainland, the late season elongated botrya of Kunzea robusta do not appear to be developed. Inflorescences of plants in these areas (called here the "eastern North Island variant") remain corymbiform (Fig. 53C), the apical vegetative bud of each inflorescence appearing to abort, and so each flowering episode is marked by a further series of brachyblasts bearing inflorescences, with vegetative growth restricted to the primary axis of the main terminal branchlet of each branch system. The fruits of Kunzea robusta are mostly obconic to broadly obconic (Fig. 53I) and are on average the longest (up to 4.6 mm long), and, next to Kunzea amathicola , the widest of the New Zealand species (up to 5.3 mm wide). Further, they are usually uniformly hairy, a character shared among usually obconic-fruited species only by the decumbent shrub, Kunzea sinclairii .

Kunzea robusta has a consistent chromosome karyotype comprising four large (2.0-2.5 μm), six intermediate (1.5-1.8 μm) and one small (0.6 μm) set of chromosomes ( de Lange and Murray 2004). With the exception of Mt Egmont samples, the combined sequence data obtained from the ITS and ETS marker regions showed that Kunzea robusta had the same sequence as Kunzea sinclairii ( de Lange 2007). The only variable character in the ETS sequence of Kunzea robusta , a guanine, was shared with Kunzea amathicola and Kunzea sinclairii (Table 2 ). Three samples of Kunzea robusta from Mt Egmont National Park provided the only departure from this pattern, possessing a guanine/cytosine mix (Table 2 ). The same mix is shared with Kunzea ericoides , Kunzea linearis , Kunzea salterae , Kunzea serotina and Kunzea toelkenii (Table 2 ; see also de Lange 2007). Previously, de Lange and Murray (2004) and de Lange et al. (2004) had regarded the Mt Egmont Kunzea populations as comprising another, potentially unnamed species, Kunzea aff. ericoides (f). This decision was based in part on the presence of this guanine/cytosine mix but also because of the behaviour of cultivated Mt Egmont plants, which retained their glaucescent, juvenile foliage despite flowering. However, this juvenile form is not retained in the wild, and adult trees are otherwise indistinguishable from the more usual form of Kunzea robusta . It was concluded that the neotonic form and flowering of the cultivated plants was probably induced through these plants (in effect 2 m tall individuals) becoming root-bound and stressed rather than having a genetic basis. To confirm this two of the Egmont Kunzea were planted and these ceased flowering and developed ‘adult’ foliage (i.e., foliage typical of Kunzea robusta elsewhere) within one year of planting. Finally, the chromosome complements of the Egmont plants, which were not reported on by de Lange and Murray (2004), are consistent with those of all other Kunzea robusta populations. Therefore, Mt Egmont plants, despite the apparently anomalous, persistent juvenile form exhibited by cultivated specimens grown at the University of Auckland, is treated here as Kunzea robusta .

Nevertheless, some regional variants within Kunzea robusta can be distinguished. However, as these tend to intergrade across wide parts of their range with other forms of Kunzea robusta and I can find no clear zones of sympatry or ecological partitioning, I feel that little purpose is served by further formal taxonomic division of this species. That said, one notable variant may repay further study. This variant, called here the "Rangitikei variant" is mostly found within the Rangitikei River catchment in the calcareous siltstone ( ‘papa’) country from about Hunterville and Umutoi north to near Moawhango. This variant differs markedly from other Kunzea robusta with respect to the branchlet indumentum (Fig. 56) and leaf size of the seedlings and juveniles. While Kunzea robusta is markedly heteroblastic, the usual condition (with the exception of some eastern North Island populations that may have smaller linear to linear-lanceolate leaves) is for the juvenile to have much larger, laxer, oblanceolate leaves than the adult. Even so, the juveniles consistently still have the long, antrorse-appressed branchlet indumentum typical of the species throughout most of its range. In the Rangitikei this is not the case. There, juveniles have short, divergent hairs (Fig. 56A, B) of the form seen also in Kunzea serotina (see Fig. 10A-E). Further, as with Kunzea serotina , they typically have an erect, more or less pyramidal growth habit, though with more broadly spreading branches than is the case in Kunzea serotina . The juvenile leaves of these Kunzea robusta populations are generally smaller than the adult (up to 6.3 × 1.5 mm in the juvenile cf. up to 28.4 × 2.5 mm in the adult). Although particularly distinctive I have retained this variant within Kunzea robusta because this juvenile condition is lost in the adult which develops the more usually antrorse-appressed branchlet hairs typical of the species elsewhere (Fig. 56C-H), and because the rDNA ITS and ETS sequences, and chromosome complements are typical of Kunzea robusta from elsewhere ( de Lange 2007; de Lange and Murray 2004). Another variation on branchlet indumentum is seen in the "eastern North Island variant" which occurs mainly in the East Cape area of the North Island. Here, in a narrow band of mainly coastal or near coastal lowland locations from about Oweka south to the northern portion of the sand tombolo of Mahia Peninsula, Kunzea robusta populations have mixtures of long antrorse-appressed and short divergent hairs (Fig. 57). These populations also tend to have linear to linear-lanceolate, spreading leaves and corymbiform inflorescences (Fig. 53C). Similar plants also occur along the eastern side of the Coromandel Peninsula and on Tuhua (Mayor Island) but these have only the long, antrorse-appressed indumentum typical of most Kunzea robusta populations and corymbiform to shortly elongate inflorescences. Again the DNA sequences and chromosome karyotypes of "eastern North Island variant" conform to the rest of the range exhibited by Kunzea robusta (Egmont plants excluded) ( de Lange 2007, de Lange and Murray 2004) which precludes, at this stage at least, any further taxonomic subdivision.

Throughout its range Kunzea robusta is sympatric with all but the allopatric Three Kings endemic, Kunzea triregensis . Branchlet indumentum alone readily distinguishes Kunzea robusta from species with divergent and or divergent curled hairs, e.g., Kunzea ericoides , Kunzea salterae , Kunzea serotina , Kunzea tenuicaulis . Further detailed distinctions between Kunzea robusta and these species are provided under their treatments and in Table 1 . Although Kunzea toelkenii mostly has divergent hairs, these are characteristically short, curled and/or spiralled and often occur in mixtures with long, appressed-antrorse hairs, so indumentum is not helpful in distinguishing it from Kunzea robusta . In Kunzea toelkenii it is the multi-trunked growth habit, sinuous, twisted, pendulous branches, and trailing epicormic growth that distinguish it from Kunzea robusta in the field. The spiciform inflorescences and sessile to subsessile flowers of Kunzea linearis immediately distinguish it from Kunzea robusta (see Kunzea linearis and Table 1 for further differences). Kunzea amathicola differs from Kunzea robusta by having consistently elongate inflorescences, and flowers which are subtended by a persistent oblong, oblong-obovate, broadly obovate to elliptic, dark glossy green pherophyll. Other distinctions are offered under Kunzea robusta and in Table 1 .

Ecology.

Kunzea robusta is the species that has most usually been described in ecological treatments of " Kunzea ericoides " ( Burrows 1973; Wardle 1991) because it is the most widespread member of the genus in New Zealand. It is mostly found in coastal and low lying areas and adjacent hill country. It does not usually grow in upper montane situations though it has occasionally been collected in places up to 1000 m a.s.l. Favouring disturbance, this is the species that is most frequently seen colonising marginal hill country, particularly in areas with slip-prone, poorly draining clay soils, or in the clay soils of the drier, drought-prone eastern parts of both islands. It is sometimes regarded as a serious weed in these habitats because of its ability to rapidly reclaim rough pasture land.

Kunzea robusta is, as a rule, not common within relatively intact indigenous forest systems, being mostly seen colonising slip scars, and other areas of damage resulting from flooding and/or storm damage. Nevertheless, in some forest types such as that dominated by kauri (Fig. 58A), occasional stands or scattered mature canopy trees can be found with ages of between 200 and 280 years ( de Lange 2007). On occasion, such as within the calcareous siltstone-dominated landscapes of the northern Hawke's Bay and Rangitikei, it can form a distinct, forest type. This is probably because the siltstones are naturally prone to frequent slipping, thus maintaining sufficient disturbance to ensure the persistence of this species. Kunzea robusta is usually found in association with Sophora tetraptera J.S.Mill. (Hawke's Bay) and Sophora godleyi Heenan et de Lange (Rangitikei) in these forest types. Sometimes it may be found growing with black beech ( Fuscospora solandri ) in these areas.

As a species, Kunzea robusta provides a key habitat for a host of fungi ( McKenzie et al. 2006), and the deep leaf litter it produces is also favoured by terrestrial orchids, especially of the genera Acianthus , Caladenia , Corybas , Gastrodia , and Pterostylis . The branchlets are often heavily parasitised by the dwarf mistletoe Korthalsella salicornioides , and in some locations by the green mistletoe ( Ileostylus micranthus ). In many areas, Kunzea robusta is the favoured habitat of geckos of the genera Dactylocnemis , Hoplodactylus , Mokopirirakau , Naultinus , Toropuku and Woodworthia (R. Hitchmough pers. comm.).

As a rule the bark of Kunzea robusta supports little other vegetation. However, in some sites it can be heavily colonised by lichens, usually of the genera Coccocarpia Pers., Crocodia Link, Heterodermia , Pannaria , Parmeliella Müll.Arg., Parmotrema , Physcia (Schreb.) Michx., Pseudocyphellaria , Punctelia Krog, Usnea J.Hill, Ramalina , and Chrysothrix Mont. Kunzea robusta is also host to a range of hornworts, liverworts and mosses. Of these, mosses are typically scarce, though occasionally, such as near the branch bases and forks, growths of Leptostomum macrocarpa (Hedw.) Pyl. may be common. Sparse patches of Hypnum cupressiforme Hedw., and Macromitrium spp., especially Macromitrium brevicaule (Besch.) Broth., Macromitrium gracile (Hook.) Schwägr., Macromitrium longipes (Hook.) Schwägr, and less frequently Macromitrium submucronifolium C.Muell. et Hampe may also be found on the mid trunk and branches. The liverwort flora of Kunzea robusta is more diverse with 40 species having been recorded from its bark (J. E. Braggins pers. comm.). The most commonly encountered of the liverworts seem to be species of Acrolejeunea (Spruce) Schiffn., Austrolejeunea (Schuster) Schuster, Frullania , Lejeunea and Metzgeria , followed by Harpalejeunea latitans (Hook.f. et Taylor) Grolle, Drepanolejeunea aff. aucklandica , Metalejeunea cucullata (Reinw., Blume et Nees) Grolle and Siphonolejeunea nudipes (Hook.f. et Taylor) Herzog. In contrast only one species of hornwort, Dendroceros granulatus Mitt., is commonly associated with Kunzea robusta bark.

Hybridism.

Kunzea robusta is sympatric with all the other New Zealand Kunzea species except the allopatric Three Kings endemic Kunzea triregensis . With the exception of that species, and also Kunzea salterae and Kunzea toelkenii , putative field evidence for hybrids involving the other six species is common, and these hybrid combinations ( Kunzea amathicola × Kunzea robusta , Kunzea ericoides × Kunzea robusta , Kunzea linearis × Kunzea robusta , Kunzea serotina × Kunzea robusta , Kunzea sinclairii × Kunzea robusta , Kunzea robusta × Kunzea tenuicaulis ) are discussed in detail under the preceeding species and in de Lange (2007). Significantly, these putative hybrid observations are all supported by experimental evidence which showed that hybrids using Kunzea robusta (see de Lange et al. 2005, as Kunzea aff. ericoides (b)) as either pistillate or staminate parent were readily produced between all species, except Kunzea salterae which was unavailable during that study. All hybrid combinations were successfully raised and flowered, and none showed any reduction in pollen fertility or seed set when selfed.

Vernacular name.

It is Kunzea robusta which is the species now most frequently meant when people use the name ‘kanuka’. The meaning and origin of the name ‘kanuka’ is however, uncertain ( de Lange 2013). The name seems to have first appeared in the East Cape area about 1871 ( Orsman 1997). Despite this, the majority of herbarium specimens collected between the 1860 and the 1930s refer to this species (and indeed the Kunzea species recognised here collectively) as ‘manuka’ and this is the name by which it is still most commonly referred to by elders of, especially, northern North Island Maori. Interestingly, according to Kirk (1889), Colenso asserted that Kunzea ericoides (and in this case he almost certainly meant Kunzea robusta ) was universally known as ‘manuka-rauriki’ (see also Laing 1907), a name that I have not heard spoken, seen written down on any herbarium specimen, or mentioned in any other literature. Despite the supposed origin of ‘kanuka’ in the East Cape area ( Orsman 1997), Kirk (1889) records that, aside from the universal name manuka, in the East Cape area Kunzea (and in this case definitely the Kunzea robusta described in this paper) was also known as ‘maru’ ( Kirk 1889) a name I heard used by Tuhoe elders in Te Urewera National Park in the 1980s. In the South Island, based on early herbarium records (1830s, 1840s) the French also recorded the name ‘titira’ and ‘atitire’ for both Kunzea robusta (Akaroa specimens) and Kunzea ericoides (Abel Tasman coastline), although these names may simply be a transliteration of 'ti tree’ as in 'tea tree’ because even by that time, the fresh and dried leaves of Leptospermum and Kunzea were routinely being brewed as a tonic by many Maori who had adopted the 'tea drinking’ practice through observation of and/or intermarriage with European whalers/settlers whose women used these genera as a tea ( Camellia sinensis (L.) Kuntze) substitute. In the far north of the North Island, aside from ‘manuka’ Kunzea robusta is still also occasionally referred to by Ngati Kuri, Te Rarawa, and Nga Puhi iwi as ‘rawirinui’, to distinguish it from the smaller and more slender ‘rawiri’ ( Kunzea linearis ) and ‘rawiritoa’ ( Kunzea amathicola ) (L. Foley pers. comm.).

Conservation status.

Kunzea robusta , as the most widespread and abundant of the New Zealand Kunzea , is here regarded as 'Not Threatened’ using the criteria of Townsend et al. (2008).