Manoao colensoi (Hook.) Molloy

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Credits

Tom Christian (2022)

Recommended citation
Christian, T. (2022), 'Manoao colensoi' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/manoao/manoao-colensoi/). Accessed 2022-06-29.

Genus

Common Names

  • Manoao
  • Silver Pine
  • Westland Pine

Synonyms

  • Dacrydium colensoi Hook.
  • Dacrydium westlandicum Kirk
  • Lagarostrobos colensoi (Hook.) Quinn
  • Lepidothamnus colensoi (Hook.) de Laub.

Other taxa in genus

    Glossary

    dbh
    Diameter (of trunk) at breast height. Breast height is defined as 4.5 feet (1.37 m) above the ground.
    endemic
    (of a plant or an animal) Found in a native state only within a defined region or country.
    indigenous
    Native to an area; not introduced.
    pioneer species
    Early colonists of disturbed areas.

    Credits

    Tom Christian (2022)

    Recommended citation
    Christian, T. (2022), 'Manoao colensoi' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/manoao/manoao-colensoi/). Accessed 2022-06-29.

    Evergreen, dioecious (rarely monoecious) trees to 15(–20) m × 1 m dbh. Crown of young trees dense, pyramidal, rounded in old trees, first order branches strongly assurgent; trunk often strongly tapered. Suckering shoots from underground stems often prolific in wild populations. Bark grey or grey-brown (yellowish brown when first exposed); on mature trees exfoliating in large plates leaving distinct ‘wave and hammer’ marks. Foliage of two types, juvenile and adult: juvenile leaves acicular, 6–13 mm long, flattened with an obvious midrib on both sides, stomata in two distinct bands usually most prominent on the upper surface, apex acute; adult leaves scale-like, spirally arranged, adpressed, imbricate, rhomboid in appearance, c. 1.5–2.5 × 1 mm, lower surface keeled, stomata scattered in dots on both surfaces. Branchlets with juvenile leaves may occasionally appear on adult trees; foliage intermediate between juvenile and adult foliage types is common on suckering shoots. Pollen cones terminal, sessile, 4–6 × 2–2.5 mm, microsporophylls 6–8(–12), rhombic to triangular with two red basal pollen sacs. Seed cones terminal, solitary or in pairs on short curved branchlets, 3–4(–8) mm long with 2–5(–6) spirally arranged fertile bracts. Seeds 1–5 per cone, erect, 3–4 × 2–3 mm, rounded in cross section with a notched apex, dark purple to black, base enclosed in a swollen, fleshy, yellowish-green epimatium (scale) remaining pruinose-green at maturity. (Farjon 2017Debreczy & Rácz 2011Molloy 1995).

    Distribution  New Zealand North Island, from Mangonui to Ruapehu; South Island, along the west coast; Stewart Island (?)

    Habitat Lakeshores and bogs in high-rainfall areas from sea level to 1000 m asl, often associating with Leptospermum scoparium, Dacrycarpus dacrydioides, and in mixed broadleaf-coniferous forest with associates including Dacrydium cupressinum, Nothofagus spp., Prumnopitys ferruginea and P. taxifolia.

    USDA Hardiness Zone 8b-9

    RHS Hardiness Rating H3

    Conservation status Least concern (LC)

    Taxonomic note The generic name Manoao is derived from an indigenous Maori name for M. colensoi, which continues to be used as a common name for this tree in New Zealand and elsewhere. Rather confusingly, the same vernacular name is also applied to another New Zealand conifer, Halocarpus kirkii, endemic to the North Island.

    A pioneer species of infertile bogs native to high-rainfall areas of the North and South Islands of New Zealand, Manoao is absent from the drier east of the country and the far north (Dawson & Lucas 2016). The same authors note that Manoao is absent from Stewart Island (off the southern tip of the south island) and the New Zealand Plant Conservation Network species account (de Lange 2022) appears to agree. Farjon (2001), however, suggests it does occurs on Stewart Island, as do many other recent works on conifers (several of which no doubt adopt Farjon’s view on such details as a matter of course). A curious trait of Manoao, particularly for any student of conifers, is this species’ peculiar ability to spread via underground stems which then ‘sucker’, ultimately giving rise to new trees. This behaviour is extremely rare among conifers, but is also reported to occur occasionally in another New Zealand genus, Phyllocladus (Molloy 1995). Manoao’s timber is durable and strong, but not heavy, and can be very beautiful – it has long been prized in New Zealand for many uses including carpentry and furniture making, but native trees are now protected (Farjon 2017).

    Manoao has a meagre presence in cultivation; it was reported from only ten gardens in a global survey of ex-situ conifer collections (Shaw & Herd 2014) and is barely utilised as an ornamental in its native New Zealand, and then only in gardens that fall within its preferred climatic zone. It has apparently been cultivated in the UK and Ireland for some time but it has never been more than a collector’s item here and appears to have only ever been represented by a handful of plants at any one time. Alan Mitchell knew of two: ‘one at Castlewellan 3 feet [c. 1 m] high, had juvenile foliage mixed with the adult. The other is 7 feet tall at Borde Hill’ (Mitchell 1972). Mitchell does not date these observations, but a plant – perhaps the same, perhaps not – at Castlewellan was c. 2 m in 1966 (Hanan 72). The largest on record is a tree that grew at Rowallane, also Northern Ireland, 9 m × 27 cm dbh in 2004 but since lost (Tree Register 2022). By 2022 the only extant specimens noted by the Tree Register are two young trees at Tregrehan, Cornwall. Planted in 1998 they were 3 m × 4 cm dbh and 3.5 m × 4 cm in 2014 (Tree Register 2022); in early 2022 they were c. 5 and 5.5 m respectively (T. Hudson pers. comm.). Manoao is represented at the Royal Botanic Garden Edinburgh, where it is kept under glass, by plants descended from collections made in New Zealand in 1984 (Royal Botanic Garden Edinburgh 2022), but in a warming climate it is likely that Manoao has a better prospect now than ever before; nevertheless, it remains a subject for very wet, mild localities, and even here is likely to remain of interest and value only to (ardent) collectors. It can easily be propagated from seed, otherwise hardwood cuttings are suggested (de Lange 2022).