(Fig. 29A). T. Kirk, The Forest Flora of New Zealand (1889), Plate LXIX (t.69), f.2.

(here designated) (Fig. 29B). Ahatawapa, Waitemata T. K[irk] 953, Feb 6 1866, WELT SP29435! Labelled by Kirk as Leptospermum ericoides A. Rich. Fl. N. Z. 357 var. lineatus [sic].

Kirk (1889; p. 125) published Leptospermum ericoides var. linearis with a brief description which is given here in full: ‘var. β, linearis. Young shoots, leaves, and calyces silky; branchlets densely crowded; leaves linear and pungent, ¹/₄₀ in. wide, margins slightly recurved; calyx with more acute teeth; petals very small, crumpled. Calyx-teeth erect in fruit. This is probably a distinct species.’ This description was accompanied by a small, somewhat stylised illustration (‘f.2’) of a fruiting sprig (Fig. 29A). No locations were given or other specimens cited. Therefore, as the sole element accompanying the protologue I regard this illustration as the holotype (see Article 9.1, Note 1, especially the statement: ‘if the author used only one element, it must be accepted as the holotype’). This is because, despite the wealth of collections in the Kirk herbarium at WELT and additional gatherings at K, all labelled in Kirk’s hand with his new name (though often spelled var. lineatus, and/or or var. lineatum (see also Kirk 1899)), Kirk (1899) did not cite any of these in his protologue, leaving the illustration, which accompanies the description and its direct citation by the naming author (e.g., ‘f.2’), as the only possible choice. However, as the holotype is stylised it is inadequate to allow a precise application of the name Leptospermum ericoides var. linearis, therefore in accordance with Article 9.8 of the International Code of Nomenclature (McNeill et al. 2012) I designate WELT SP029435 as epitype (Fig. 29B). This sheet comprises two fruiting specimens which clearly show the densely crowded branchlets, linear leaves, and fruits bearing persistent, erect calyx lobes. These are some of the distinguishing characters mentioned in Kirk’s protologue for his new variety (Kirk 1889; p. 125). Further, the specimens were clearly collected by and labelled in Kirk’s hand as ‘Leptospermum ericoides var. lineatus’.

The specific epithet linearis refers to the linear leaves of this species, a condition much remarked upon by Thomas Kirk on his herbarium specimens, and to a lesser extent in his descriptions (Kirk 1889, 1899).

(Figs 30, 31, 32). Growth habit erect shrubs or small trees up to 12 m forming dark green to silvery-grey, erect but more or less rounded, plumose, densely branched canopies up to 2 m diam., sometimes (usually on ultramafic rocks) decumbent and/or trailing. Trunk 1(–4 or more), mostly erect but in trailing specimens distinctly serpentine, 0.10–0.46(-0.60) m d.b.h.; basal portion of trunks initially covered with rather thick, firm, stringy, brown to brownish grey coriaceous bark. Bark early bark firmly coriaceous, dark brown to brown, ± elongate, usually bearing a few transverse cracks (especially on branch flanges and decurrent leaf bases) otherwise remaining firmly attached, margins elongate sinuous, ± entire with scarcely any flaking; old bark similar though more distinctly corky-coriaceous, coarsely tessellated and remaining firmly attached, if detaching then usually doing so along transverse cracks, and peeling inwards to leave distinct layers of chartaceous, lunate, flakes that are centrally attached; flakes usually with highly irregular, frayed and shattered apices, otherwise margins ± entire; upper surface of bark flakes tessellated; upper trunk bark crumbling readily in hand, shattering if pulled hard into numerous, small, tabular flakes. Branches numerous, usually present from close to or at trunk base, but becoming progressively confined with age to the upper half of trunk; ascending to upright, very rarely spreading (usually in decumbent plants), usually distinctly plumose and often bearing old fruits; branchlets numerous, plumose, rather slender, ± quadrangular to subterete, leaves crowded along stems; branchlets sericeous, indumentum copious, hairs antrorse-appressed, weakly flexuose, up to 0.68 mm long, hyaline to translucent (appearing silvery when young, maturing silver-grey). Vegetative buds inconspicuous, usually obscured from view by surrounding leaves; at resting stage 0.2–0.8 mm diam. narrowly ovoid; scales deciduous; (0.2–)1.2 mm long, stramineous to pale brown, broadly ovate-lanceolate grading through lanceolate to narrowly lanceolate; midrib strongly keeled, prolonged to apiculate tip, often with one prominent row of 2–6 oil glands on either side of midrib; scales initially completely obscured by long silky silvery-white hairs, becoming glabrate, with hairs progressively confined to scale margins, midrib, and keel prolongation. Leaves not heterophyllous, sessile, usually hairy, very rarely glabrous, densely crowded along branchlets, particularly toward apices, initially obliquely ascending, subappressed to suberect, basally often spreading to weakly recurved in distal one-third; lamina (9.3–)12.7(–19.5) × (0.3–)0.7(–1.2) mm, initially silvery-grey (due to dense hair covering), maturing dark green to glaucous green above (as hairs are shed) with a dull not glossy surface, paler beneath; lamina linear, distal one-third sometimes weakly recurved, apex sharply acute, cuspidate, base attenuate (with adaxial surface often glabrous, abaxial densely hairy); adaxial lamina surface flat to weakly concave, glandular punctate, with oil glands evident when fresh or dry (though more conspicuous when dry), up to c.300, midrib very slightly raised near base, otherwise only evident for c. one-third of length as a conspicuous line of silvery-grey antrorse-appressed, silky hairs up to 0.8 mm long; abaxial surface flat to weakly convex, glandular punctate, oil glands up to 300; midrib raised for entire length, densely sericeous to just short of leaf apex, hairs as for adaxial midrib and lamina margins; lamina margins copiously covered in silvery-grey hairs, these forming a thick band and fusing with the abaxial midrib hairs just short of lamina apex, and along decurrent leaf bases. Perules deciduous, (0.3–)1.8(–2.3) mm long, straminaceous to pale brown, narrowly ovate, ovate-lanceolate grading through to narrowly lanceolate; midrib strongly keeled, cuspidate, with an obscure row of 2–8 oil glands on either side of midrib; lamina initially obscured by long silky silvery-white hairs, becoming glabrate, with hairs progressively confined to scale margins, midrib, and keel prolongation. Inflorescence mostly compact, spiciform (3–)8(–12)-flowered botrya 20–80 mm long; usually on brachyblasts with the terminal shoot either bearing a slightly longer (up to 180 mm) compact 6–15-flowered, spiciform botryum, or a greatly elongated, spiciform, 10–40-flowered botryum up to 180 mm long. Flowers of smaller botrya crowded, those of elongated botrya regularly spaced up to 20 mm apart; terminal portion of both short and elongated spiciform botrya inflorescence types often bearing undeveloped flowers and active vegetative growth. Inflorescence axis densely invested in antrorse-appressed, weakly flexuose, silky hairs. Pherophylls persistent, leaf-like, 1–2 per flower, closely clasping hypanthium base, usually hairy, very rarely glabrous; lamina (6.0–)9.8(–12.8) × (0.9–)1.8(–2.2) mm, dark silvery-green, silvery-grey or glaucous (depending one extent of hair covering), linear to linear-falcate; linear-falcate pherophylls with basal portion sharply bent almost at right angles to inflorescence axis, otherwise obliquely ascending to suberect, or spreading; apex acute, base attenuate; adaxial surface usually deeply concave to weakly so, glandular punctate, oil glands up to c.100 (usually fewer); midrib slightly raised near base, otherwise indistinct, bearing antrorse-appressed, silky, hairs for whole length or glabrous; abaxial surface deeply convex, glandular punctate, oil glands up to 100 (usually fewer); midrib scarcely evident especially if glabrous, otherwise mostly evident as a dense line of antrorse-appressed, silky hairs continuing to the apex, lamina margin usually densely covered by antrorse-appressed, sericeous hairs, sometimes glabrous. Pedicels sessile to subsessile, up to 1.2 mm long at anthesis, scarcely elongating after anthesis, terete, copiously invested with silky, antrorse-appressed, weakly flexuose, hairs. Flower buds ovoid, double conic to pyriform, apex sharply erect; calyx lobes pinched at apex inwards, and touching prior to bud burst. Fresh flowers when fully expanded (1.9–)3.9(–5.7) mm diam. Hypanthium (2.0–)2.8(–4.0) × (2.5–)3.4(–4.1) mm, with free portion 0.6–0.9 mm long, silvery-white to silvery-grey due to copious covering of hairs or dark red-green if glabrous; barrel-shaped, cupular or narrowly campanulate, terminating in scarcely defined chartaceous rim bearing 5 persistent sharply erect calyx lobes; hypanthium surface smooth, usually completely covered in a dense covering of long, silky, antrorse-appressed silvery hairs; ribs scarcely evident. Calyx lobes 5, erect, subcoriaceous, (1.0–)1.3(–1.6) × (0.2–)0.4(–0.6) mm, persistent, narrowly deltoid to deltoid with acute tips, red-green, weakly keeled or not, lobes densely covered in long, silky, silvery, antrorse-appressed, hairs or glabrous; margins green flushed pink or red, oil glands evident only in glabrous forms, rather inconspicuous, ± colourless. Receptacle green or pink at anthesis, usually darkening to crimson after fertilisation. Petals 5(–6), (0.9–)1.4(–2.0) × (0.7–)1.4(–1.9) mm, cream, pale pink or cream basally flushed pink, narrowly ovate to suborbicular, suberect, upper one-third sometimes weakly recurved, apex rounded, margins ± finely and irregularly crumpled, sometimes denticulate, oil glands colourless. Stamens 32–46(–60) in 1–2 weakly defined whorls, arising from receptacular rim, filaments cream. Antipetalous stamens (2–)3(–6) sometimes petaloid, antisepalous (3–)4(–7). Outermost antipetalous stamens initially erect with the upper portion often incurved, more rarely outcurved, on filaments 1.2–1.8 mm long, inner stamen if present, 0.9–1.6 mm, erect or incurved, often a further 1–3 stamens, of similar length to inner stamens may be present at the base of the outermost antipetalous pair. Antisepalous stamens shorter than outermost antipetalous stamens, 0.8–1.0 mm, erect or weakly to strongly incurved, rarely outcurved, usually in mixtures of both. Anthers dorsifixed, 0.04–0.06 × 0.02–0.04 mm, testiculate, latrorse. Pollen white (13.2–)16.2(–21.0) μm. Anther connective gland prominent, pale pink or golden-yellow when fresh, drying yellow to pale orange, spheroidal, finely to coarsely papillate. Ovary (3–)4(–5) locular, each with 18–26(–30) ovules in two rows on each placental lobe. Style 0.8–2.0 mm long at anthesis, elongating after anthesis, cream or pale pink; stigma narrowly capitate, as wide as, or slightly wider than style, ± flat, greenish-white or pink, flushing red after anthesis, surface finely granular-papillate. Fruits long persistent, (1.6–)2.3(–2.9) × (2.3–)3.0(–4.1) mm, initially silvery-white or silvery-grey due to dense hair covering, maturing grey-brown to grey-black depending on degree of hair loss, sometimes completely glabrous in which case dark brown; in all types fading with age to pale grey in exposed situations or grey-black in shade, barrel-shaped to narrowly obconic, rarely campanulate to cupular, calyx valves prominently erect, splits concealed by dried, erect, free portion of hypanthium. Seeds 0.50–1.00(–1.10) × 0.48–0.63(–0.70) mm, obovoid, oblong, oblong-ellipsoid, or cylindrical and ± curved; usually 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: (Jul–)Nov–Jan(–May). FT: Jun–May. Chromosome Number 2n = 22 (see de Lange and Murray 2004).

(148 sheets seen): New Zealand (North Island). Te Paki, North Cape Scientific Reserve, Surville Cliffs, P. J. de Lange 1250 & G. M. Crowcroft, 30 Jan 1992, (AK 207192, Duplicates: AD, CHR); Te Paki, Tom Bowlings Bay, H. Carse s.n., Dec 1926, (CHR 296369); Te Paki, Spirits Bay/Kerr Point Road junction, R. Cooper s.n., 30 Oct 1969, (AK 121371, Duplicate: CHR); Te Aupouri, Te Kao (near school/Te Ahu road junction), P. J. de Lange 4164, 18 Jan 2000, (AK 287887; Duplicate: AD, NSW); Te Aupouri, Mt Camel, near Perpendicular Point, P. J. de Lange 1865, 15 Nov 1992, (AK 211064, Duplicates: AD, CHR); Rangaunu Harbour, Kaimaumau, R. Cooper s.n., 7 Nov 1966, (AK 117773); Waipapakauri, H. Carse s.n., 7 Jan 1902, (WELT SP077488); Kaitaia, H. B. Matthews s.n. & H. Carse, Dec 1918, (CHR 296350); Ahipara Gumfields, Waitaha Stream, P. J. de Lange 4146, 17 Jan 2000, (AK 287957); Mangonui, Rangiawhia School, R. Cooper s.n., 25 Aug 1965, (AK 123157); Mangamuka, Raetea Forest, L. J. Forester s.n., 5 Mar 1992, AK 206336; Whangaroa Harbour, Wainui Road, Waitapu Bay, P. J. de Lange 5987 & P. B. Heenan, 1 Apr 2004, (AK 286197, Duplicate: AD); Russell, Bay of Islands, D. Petrie s.n., May 1897, (WELT SP029463); Between Waimate and the Bay of Islands, W. Colenso 182, 30 Jul 1844, (WELT SP022866, Duplicate: K); Kai Iwi Lake, R. Cooper s.n., 13 Nov 1968, (AK 120232); Whangarei, near Marsden Point, R. O. Gardner 10178, 24 May 2000, (AK 251630); Pouto Peninsula, Sail Point, above Clarkes Bay, P. J. de Lange 6288 & R. O. Gardner, 10 Aug 1995, (AK 288776); Mangawhai, Molesworth Drive, P. J. de Lange 5537 & G. M. Crowcroft, 4 Oct 2002, (AK 283238); Te Arai Point Road, Te Arai, P. J. de Lange 5534 & G. M. Crowcroft, 3 Oct 2002, (AK 283237, Duplicate: CHR); Takatu Peninsula, Million Bay, Campbells Beach, P. J. de Lange 6330, 12 Jan 2005, (AK 289208); Northcote, Waitemata Harbour, North Block, ‘Aha Tawa Pa’ (Tennyson Road), P. J. de Lange 6284, 15 Nov 2004, (AK 288766, Duplicates: AD, CHR, K, MEL, NSW, NZFRI, WAIK, WELT); Birkdale, H. B. Matthews s.n., 1919, (AK 102429); Auckland, near Cox’s Creek, T. Kirk s.n., n.d., (K); Maramarua – Matamata Road (State Highway 27), 800 m north of Waikumete Stream, P. J. de Lange 4625, 7 Nov 2000, (AK 286054, Duplicates: AD, CHR, WAIK); Hapuakohe Range, Wai Iti Road, above Ohinekaua Stream, P. J. de Lange 4707, 16 Nov 2000, (AK 288490, Duplicates: AD, CHR); North Wairarapa, 1 mile west of Kupukore, A. P. Druce s.n., May 1965, (CHR 132842). Poor Knights Islands: Aorangi, western ridge of Tatua Peak, P. J. de Lange 6875, 14 Jan 2007, (AK 298368, Duplicate: CHR).

(Fig. 33). Endemic. New Zealand, North Island (sea level – 310 m a.s.l.). Recorded from Te Paki south to the Ahipara Gumlands and the Karikari Peninsula. South of there it is sporadic and mainly coastal to the Waitemata Harbour. Also present on the western side of Aotea (Great Barrier Island), the eastern side of the Coromandel Peninsula (near Tairua), on the western margin of the Hauraki Plains just north of Kaihere, and within the foothills of the Hapuakohe Range. South of there Kunzea linearis is known only from a single, highly disjunct collection made by A. P. Druce (CHR 132842) from near Mt Kupukore, in the northern Wairarapa. Although I have seen no other specimens from the southern half of the North Island, I accept this record, because the collector A.P. [Tony] Druce, was a well known, cautious botanical explorer not prone to making labelling errors, and with a critical eye for the unusual (Atkinson 1999). Also, at the time of that specimen’s collection in May 1965, Druce was unfamiliar with Kunzea linearis (he had labelled his specimen ‘Leptospermum ericoides’). In fact it was not until May 1987, 22 years later that he made his next herbarium collection of Kunzea linearis from Ahipara (CHR 469707), and that gathering Druce labelled as an ‘unnamed’ species (Kunzea “Ahipara” (Druce 1993)), apparently not realising that it already had a formal name within the genus. Although subsequent searches of Mt Kupukore made at my request in 2007 by Mr Pat Enright (in litt.) failed to find Kunzea linearis there, hybrids between it and Kunzea robusta were present, suggesting its past, or continuing presence in the area.

Kunzea linearis is the most distinctive of the New Zealand Kunzea species (see Table 1). Its discovery by Thomas Kirk at Ahatawapa and Cox’s Creek, Auckland was remarked upon by Hooker (1867; p. 728) who noted it’s distinctiveness in his treatment of Leptospermum ericoides but elected not to name it because ‘the species of this genus are, however, so variable that I do not venture to make a new one of this’. Perhaps swayed by Hooker’s views, Kirk (1899) did not name it at species rank. Nevertheless in his protologue he remarked (p. 125) that ‘this is probably a distinct species’. No other species has the same combination of densely crowded erect, plumose, dark green to silvery grey branches and branchlets (Fig. 32F), covered in masses of hairy linear leaves, sessile to subsessile small flowers with suberect, crumpled petals that are borne on mainly spiciform, condensed botrya, with long linear to linear-falcate pherophylls (Figs 30A–B, 32K–L). Herbarium specimens of Kunzea linearis are particularly distinctive because they usually turn silvery-grey on drying, a colour caused by the abundance of light-reflecting silky hairs on the branchlets and leaves. In addition to these differences, Kunzea linearis is further distinguished by its unique chromosome complement comprising eight ‘large’ (1.2–1.5 μm), and three small (0.8–0.9 μm) chromosome pairs. Of the sequence regions investigated (see de Lange 2007; de Lange et al. 2010), ETS was the only site showing variation (Table 2), with Kunzea linearis differing from all other Kunzea Subgen. Niviferae at alignment positions 41 and 259 where a unique guanine nucleotide and guanine/adenine mix are present (de Lange 2007). Otherwise, Kunzea linearis shares with Kunzea ericoides a cytosine nucleotide at alignment position 269 (Table 2), and with Mt Egmont samples of Kunzea robusta, and multiple samples of Kunzea ericoides, Kunzea salterae, Kunzea serotina and Kunzea toelkenii a guanine/cytosine mix at position 232 (Table 2).

Kunzea linearis is frequently sympatric with Kunzea amathicola and Kunzea robusta, and less commonly with Kunzea sinclairii on Aotea (Great Barrier Island). It is easily distinguished from all three species in the field and the herbarium by the linear leaves, inflorescence type, pherophylls and floral features (Figs 30A–B, 32K–L; Table 1). Kunzea linearis has a superficial resemblance to Kunzea ericoides, because both species have somewhat similar long narrow leaves, such that they have been confused in past literature e.g., de Lange et al. (1997). Kunzea linearis differs from the allopatric South Island endemic Kunzea ericoides by its long, silky, antrorse-appressed, weakly flexuose branchlet hairs (Figs 30C, 31A–E), consistently dark green to almost glaucous linear leaves densely crowded toward the branchlet apices, usually condensed spiciform botrya (Figs 30A–B, 32K–L), sessile to subsessile flowers with the calyx lobes of the mature bud erect, apically pinched inwards and touching just prior to bud burst (Figs 30A, I–K, 32K–L), suberect petals, and by the usually hairy hypanthia and fruits (Fig. 30J, N).

Kunzea linearis has some similarity to the allopatric Three Kings Island group endemic Kunzea triregensis, especially as the latter sometimes has flower buds with suberect touching calyx lobes. Although the two species never meet in the wild, they have been confused in herbaria. Differences between both species are discussed in more detail under Kunzea triregensis.

Kunzea linearis is primarily a species of coastal to lowland shrubland habitats overlying impoverished soils (Fig. 32B) and peat bogs. It is only very rarely found at any distance inland. The sole exception appears to be Te Paki where it is virtually the only Kunzea species present and so seems to occupy a much greater range of habitats than it would usually (e.g., Fig. 32A). Elsewhere within its range, even in apparently suitable inland gumland scrub habitats overlying leached soils, and on the clay podzols of the Northland Peninsula, it is usually replaced by Kunzea robusta. Kunzea linearis seems to reach its greatest abundance on sand podzols overlying older usually Pleistocene-aged sand dunes, especially in places where these grade into peat. Because it is tolerant of seasonal flooding, waterlogged soils and extreme drought Kunzea linearis is usually the dominant species on the sand country of the Te Aupouri Peninsula, as well as the acidic leached clays and older sand soils of Te Paki. It is also the dominant woody shrub on the margins of the oligotrophic peat bogs and lakes of the Taumatatotara Flats (Te Paki), the Motutangi-Kaimaumau Peat Bog, Lake Ohia, Karikari Peninsula lakes and in parts of the Ahipara Gumlands. Outside these habitats Kunzea linearis has been found growing within shell banks and low-lying clay banks subject to saline inundation within the mangrove (Avicennia marina subsp. australasica (Walp.) J.Everett) swamps of the upper Whangaroa Harbour. In western Northland it may occasionally colonise mobile sand where it is then usually sympatric with and often out-competed by Kunzea amathicola. In parts of Te Paki and also on the Poor Knights Islands, Kunzea linearis can sometimes be found in abundance within mixed indigenous forests, though mostly then on skeletal soils developed on outcrops of hard volcanic rock or on deeply leached clay podzols (usually in association with kauri (Agathis australis (D.Don) Lindl.)). These situations are exceptional and, as a rule, Kunzea linearis is not found in mature forests. South of the Pouto Peninsula and Te Arai, Kunzea linearis has a very patchy. In these areas it is usually found on cliff faces growing amongst pohutukawa (Metrosideros excelsa Sol. ex Gaertn.). In places where the cliffs abut land that has been frequently fired, Kunzea linearis may be a local component of the fire-induced gumland vegetation. The peculiar disjunct distribution of Kunzea linearis south of its main Northland occurrences, and in particular the close association of the Waitemata Harbour populations with sites of former Maori habitation and fortifications, e.g., Ahatawapa and Kendal’s Bay (Fig. 32B), and some of the original sites of European settlement e.g., Devonport, Cox’s Creek, led de Lange (2006) to suggest that these Kunzea linearis populations were not natural and may have resulted from the accidental spread of seed from firewood bought by Maori to the Waitemata Harbour from the eastern part of coastal Northland during the musket wars that raged between 1810 and the close of the 1830s. While this requires further study, the majority of these southerly occurrences are in habitats not usually occupied by the species in the main part of its range, and that also invariably occur on or close to cultural sites. Alternatively it could be natural to these areas, and may have temporarily expanded its range during the initial settlement phase of Auckland to occupy freshly cleared land. However, this explanation does not address the peculiar patchy distribution of the species on Aotea (Great Barrier Island), the Coromandel Peninsula, western Hauraki Plains and the foothills of the Hapuakohe Range, where successional habitats are still common, nor its peculiar disjunction to Mt Kupukore in the eastern Wairarapa (see Fig. 33).

Kunzea linearis is sometimes heavily parasitised by the hemiparasitic dwarf mistletoe Korthalsella salicornioides. In the northern part of its range it is often festooned in dense tangles of the lauraceous hemiparasitic taihoa (Cassytha paniculata R.Br. and Cassytha pubescens R.Br.). Around Te Paki Kunzea linearis provides an important habitat for an unnamed green gecko (Naultinus “Te Paki”), and elsewhere in Te Aupouri the Northland green gecko (Naultinus grayi Bell, 1843) (R. Hitchmough pers. comm.) whilst around Auckland it is a favoured habitat for another gecko, Naultinus elegans (Gray, 1842). Two geckos of the genus Dactylocnemis Fitzinger, 1861 (Dactylocnemis pacificus (Gray, 1842) and Dactylocnemis “North Cape”) and one of Mokopirirakau (Mokopirirakau granulatus (Gray, 1845)) are also commonly found sheltering under the bark of this species (R. Hitchmough pers. comm.).

Kunzea linearis is a widespread species of northern New Zealand, and it is frequently sympatric with Kunzea amathicola in the western part of its range and with Kunzea robusta in the east. Throughout this range, but especially in places of prolonged human disturbance, the putative hybrids Kunzea amathicola × Kunzea linearis and Kunzea linearis × Kunzea robusta can be abundant. This observation is borne out by artificial hybridisation which showed that, whether used as a staminate or pistillate parent, Kunzea linearis readily formed hybrids with five of the seven other New Zealand Kunzea used in that study (de Lange et al. 2005).

Because Kunzea linearis hybrids are fully fertile there is a tendency for introgressed populations to develop, especially where local habitat conditions are prone to regular disturbance. Thus, complex introgressive hybrid swarms may occur in places that are frequently burned, subject to plantation forestry, coastal subdivision or urban development. Where conditions are extreme, such as the heavily developed northern shores of the Waitemata Harbour, Auckland, it is now difficult to find ‘pure’ examples of Kunzea linearis, as introgressed hybrid plants are dominant over much of that area.

The most commonly encountered hybrid is Kunzea linearis × Kunzea robusta. This is recognised by its foliage, which tends to be ascending rather than spreading, dark green, linear-oblanceolate rather than linear, and which has obtuse rather than acute apices. Foliar hair distribution is also markedly more variable on hybrid specimens, ranging from glabrate to distinctly sericeous hairy but with the hairs generally more restricted to the leaf margins and abaxial midribs. All putative hybrids, when fresh, have glossy leaves rather than the more usual dull dark green to silvery-grey leaf surfaces typical of Kunzea linearis. Flowering material is especially diagnostic, with the inflorescences on single individuals varying from elongate spiciform to compact corymbiform. The flowers tend to be shortly pedicellate, never sessile to subsessile, and the hypanthia broadly obconic to broadly barrel-shaped rather than barrel-shaped to sharply obconic. The hypanthia and fruit surfaces usually show a mixture of the short, antrorse-appressed hairs typical of Kunzea robusta and the long, sericeous, weakly flexuose, antrorse-appressed hairs of Kunzea linearis. In some examples the hypanthium surface may even be glabrate. An important distinction is the shape of the calyx lobes in mature buds. In Kunzea linearis these are consistently narrowly deltoid with distinctly acute apices, and in Kunzea robusta, broadly obtuse to rounded. In the hybrid they tend to be broadly deltoid with subacute to rounded apices. As with Kunzea robusta, the calyx lobes of the mature flower buds in hybrids tend to lie flat, though a few may be suberect, and, unlike Kunzea linearis, the lobes are rarely touching at bud burst. The petals of the hybrids tend to be larger than the range seen in Kunzea linearis and spreading rather than suberect, but, as with Kunzea linearis, they are often flushed pink or off-white with the margins finely crumpled. Depending on the degree of introgression, most hybrids can be readily identified by these characters.

The hybrid Kunzea amathicola × Kunzea linearis is common only in a small area between Waipapakauri, Ahipara and the adjacent, heavily modified Ahipara Plateau. Although this hybrid is fully described under Kunzea amathicola, some of the key diagnostic features are noted here to assist with distinguishing it from Kunzea linearis. Kunzea amathicola × Kunzea linearis is best recognised vegetatively by its leaves which are narrow to broadly lanceolate rather than linear to oblong, oblong-obovate to elliptic. Also they tend to be less evenly spaced than is usual for Kunzea amathicola, and, as in Kunzea linearis, are more crowded toward the branchlet apices. The shape of the pherophylls is diagnostic. Unlike Kunzea linearis which has linear to linear-falcate, ascending to spreading pherophylls, or Kunzea amathicola which has oblong, oblong-obovate, to elliptic, recurved ones, those of the hybrid are linear-oblong and spreading to weakly falcate. The flowers of Kunzea linearis are sessile to subsessile, and those of Kunzea amathicola are distinctly long pedicellate; hybrid flowers show a gradation from subsessile to shortly pedicellate (often on the same plant), and the hypanthium, calyx lobes and petals are also intermediate (see under Kunzea amathicola). The most critical difference is the shape and position of the calyx lobes, which are narrowly deltoid and erect in Kunzea linearis, broadly obtuse to rounded and suberect or spreading in Kunzea amathicola, and narrowly obtuse and suberect to erect in the hybrid. Further, as with Kunzea amathicola, the calyx lobes of fruiting hybrids are incurved from the base.

The hybrid Kunzea linearis × Kunzea sinclairii is very uncommon. Four specimens have been found on the western side of Aotea (Great Barrier Island), two flowering examples collected at “Fitzroy” (W. R. B. Oliver s.n. (WELT SP029478), W. R. B. Oliver s.n. (WELT SP029494)), and two sterile gatherings, one each from near Mt Young and Maungapiko. Oliver’s gatherings are the only wild flowering specimens of this hybrid known. The other examples are sterile but their hybrid status is evident by their distinctive foliage, and, in the one wild example I found, weakly erect, spreading, small tree habit. The foliage of all four specimens is distinctly narrow-lanceolate to almost linear, reddish silvery-grey, and copiously covered in long silky hairs. The leaf apices are sharply acute, and the margins have distinctly longer hairs than the rest of the lamina. Artificially raised hybrids of this combination were fully fertile (e.g., P. J. de Lange 5776 (AK 284581)), and produced shortly pedicellate flowers on somewhat spiciform inflorescences. The pherophylls ranged from broadly elliptic to lanceolate, and, as in Kunzea sinclairii, they are quickly shed, being present only in the early stages of floral bud development. The flowers of wild and experimental Kunzea linearis × Kunzea sinclairii hybrids are smaller than is usual in Kunzea sinclairii with hypanthia that are more narrowly obconic to campanulate, red-pigmented and copiously covered in long, antrorse-appressed hairs. The calyx lobes are suberect to erect, broadly deltoid with acute apices and very hairy margins. The lobes are very hairy along the centre, either side of which is a glabrous pale pink band. Often there is a small, deciduous apiculus.

Until recently northern Maori (specifically Te Rarawa of Te Aupouri and Ngati Kuri of Te Paki), did not recognise the name ‘kanuka’ for any species of Kunzea. All species of Kunzea from that region were universally known there as ‘manuka’, while Leptospermum scoparium (usually known outside this area now as ‘manuka’) is known there as ‘kahikatoa’ (G. Neho pers. comm.). While Ngati Kuri usually refer to Kunzea linearis as ‘manuka’ it is also known there by the name ‘rawiri’ (W. Murray pers. comm.). Rawiri was also a Nga Puhi name recorded on specimens of this species collected by the Cunningham’s from either the Bay of Islands or the Hokianga (Cunningham 1839; p. 111).

Kunzea linearis is appropriately listed as ‘At Risk/Declining’ by de Lange et al. (2013b).