Kunzea tenuicaulis de Lange

Kunzea ericoides var. microflora (G.Simpson) W.Harris

geothermal kānuka, prostrate kānuka

New Zealand endemic.

Apart from specimens in major botanical gardens, not widely cultivated and only rarely sold in gardens centres.

North Island of New Zealand, endemic to the Taupo Volcanic Zone occupying active geothermal fields from the eastern Bay of Plenty south through the Central North Island to Tokaanu, on the southern shore of Lake Taupo.

• Branches prostrate and spreading.
• Branchlets with persistent short, erect hairs.
• Leaf surfaces hairless.
• Leaf margins hairy.
• Abaxial midrib hairy.
• Leaves usually recurved from about ½ of total length.
• Fruit long persistent.

Trailing prostrate or low-growing spreading shrubs, or multi-trunked trees up to 8 m tall. Branches slender, prostrate, spreading or arching, or pendulous in larger plants.

Bark corky to papery, coarsely fragmented into small squares. Branchlets with copious persistent hairs.

Leaves, alternate, oblanceolate to obovate, (1–)2–6(–10) mm long, 1–2(–3) mm wide, leaf surfaces hairless, glossy dark green or red-green, usually recurved from about ½ of total length, surfaces not puckered; margins entire, hairy; tips acute; leaf stalks absent or short.

Flowers borne in compact clusters to 25 mm long, axis densely hairy; flowers ± 3.5–9 mm in diam., stalks present, petals 5, mostly white, sometimes pink, oil glands usually not evident when fresh (sometimes pink), drying colourless; sepals 5, tips free, erect, persistent, thickened towards the base; stamens 10–32, white, longer than petals. Main flowering period: spring, but some flowers may be present from late winter to autumn.

Fruit dry, persistent, (3–)4(–5)-locular, ± 2–3 mm wide, flat-topped when valves closed.

Readily distinguished from all the other species of Kunzea by its prostrate to decumbent habit, slender, often pendulous branchlets combined with hairless leaf surfaces and sepals thickened towards the base. Within its geothermal habitats K. tenuicaulis grows with K. serotina and K. robusta. Kunzea serotina has an erect, columnar to pyramidal growth habit with upswept branches and the flower petals have yellow oil glands. Kunzea robusta has a much larger tree habit, with stouter branches bearing much larger linear-lanceolate, lanceolate to oblanceolate leaves, and the branchlet hairs are appressed rather than erect.

Kunzea tenuicaulis has a 2018 conservation status of Threatened – Nationally Endangered.

The genus Kunzea also occurs in Australia, where it is represented by more than 50 species of which three (K. ambigua, K. baxteri, K. parvifolia) are cultivated occasionally in gardens in New Zealand; another nine species are recorded as having been included in research trials or as rare garden occurrences.

• CitSciHub
• Flora of New Zealand Online
• GBIF
• iNaturalist NZ
• NZPCN