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Halocarpus bidwillii
Conservation status
Least Concern  (IUCN 3.1)
Not Threatened (NZ TCS)
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Gymnospermae
Division:	Pinophyta
Class:	Pinopsida
Order:	Araucariales
Family:	Podocarpaceae
Genus:	Halocarpus
Species:	H. bidwillii
Binomial name
Halocarpus bidwillii (Hook. f. ex T. Kirk) Quinn
Synonyms
Dacrydium bidwillii Kirk Dacrydium bidwillii var. erecta Kirk Dacrydium bidwillii var. reclinata Kirk

Halocarpus bidwillii, commonly known as the mountain pine or bog pine, is a species of conifer in the family Podocarpaceae. It is endemic to New Zealand and can be found throughout the North and South Islands.

It is an evergreen shrub favouring both bogs and dry stony ground, seldom growing to more than 3.5 m (11 ft) high. The leaves are scale-like on adult plants, 1–2 mm (0.039–0.079 in) long, arranged spirally on the shoots; young seedlings and occasional shoots on older plants have soft strap-like leaves 5–10 mm (0.20–0.39 in) and 1–1.5 mm (0.039–0.059 in) broad. The seed cones are highly modified, berry-like, with a white aril surrounding the single 2–3 mm (0.079–0.118 in) long seed.

Description

H. bidiwillii grows as a shrub. It grows up to 4.8 m (15.7 ft) tall and has a short trunk that Kirk noted "rarely exceeds" 1 foot in diameter, and more commonly has a thickness between 30–40 cm (12–16 in) at breast height. Its bark is red to brown and trunks have multiple branches, though will occasionally have just one. In some rare cases, as the horizontal branches grow, their roots will form a "bush" around the parent shrub. This creates a vast mini-forest that looks like a huge low tree or shrub. The parent tree may die, leaving its outliers intact which are thin and red.

Depending on the maturity of a mountain pine, the shrubs take on rather drastic differences in leaf appearance. In the juvenile state, leaves are linear, flat, and spreading, much like a pine tree, while in the mature state, its leathery leaves, 1–2 mm long, take on an overlapping scaled appearance, much like the scales of a fish. The leaves are green when fresh, but can become brown to red when they are dried out. During the flowering months of October to December, small male cones, 3–5 mm in length, are brown to red at the end of the pine's scale-like leaves. Stomata can be seen by the naked eye and seen as white spots. Pollen particles are solitary, terminal, ca. 3–5 mm long. Appendage is adnate to base of carpel, cortex, inverted, with a drooping ovule. The fruit of mountain pine consists of a dark brown, black-brown to purple-brown seed in a fleshy, waxy white cup. Seeds are 2–3 mm long, subglobose, compressed, with a white to yellow aril. The aril is V-shaped under the seed. Seeds are hairless, smooth, 3–4.5 mm long (including arils), and take on a dark brown or dark brown to dark purple brown appearance; seeds are also typically shiny, oval oblong, and compressed.

Bog pines are easily recognized when fruiting by the waxy white (very slightly yellowish) arils subtending the seed. Vegetatively compared with other species of Halocarpus, mountain pines have growth habits of smaller multibranched shrubs to small trees, weak keel-shaped leaves, and more slender, initially quadrangular branchlets. The seeds of the mountain pine are distinguished from H. biformis (with which it often confused with) by the ventral and dorsal surfaces which are usually significant longitudinally grooved (sometimes only on the ventral surface).

Taxonomy

Halocarpus bidwillii was first described by the British botanist Thomas Kirk in 1887, in an article in the Transactions and Proceedings of the New Zealand Institute, as Dacrydium bidwillii. He identified two variants that he differentiated mostly on the basis of branch and inflorescence (flower spike) shape. The alpha (α) or erecta variety had flat and ribbed leaves with slender branches, while the beta (β) or reclinata variety had distinct mid-rib leaves and stout branches. Harry Allan disputed the status of these varieties in his 1961 Flora of New Zealand (Vol 1), suggesting instead they were the result of hybridisation. It wasn't until 1982 when C.J. Quinn proposed an alternative taxonomy for the species based on ovule morphology and orientation, that the species obtained the current scientific name of Halocarpus bidwillii.

Etymology

The specific epithet bidwillii is in honor of John Carne Bidwill (1815-1853) who was an Australian botanist born in England and became the first director of the Royal Botanic Gardens, Sydney.

Phylogeny

Three separate studies using DNA sequencing, one in the year 2000, and two in 2002, have confirmed that the genus Halocarpus is monophyletic, as they all descend from a common ancestor, though the wider clade it is part of was found to be unresolved. A study in 2002 from the journal of Plant Systematics and Evolution found a relationship in which H. kirkii and H. biformis form a clade, to which H. bidwillii is sister. This was replicated in a previous study from 2000 in the Australian Journal of Botany.

Subsequent studies from 2011 and 2012 however, have found that H. bidwillii instead forms a clade with H. biformis, to which H. kirkii is sister. These studies, in the Journal of Botany and Smithsonian Contributions to Botany, used data from the GenBank as well as their own de novo sequencing. One study analysed MatK, trnL–trnF and ITS2 DNA, while the other used plastid and mitochondrial loci, 18S rDNA, 26S rDNA, and ITS2 DNA as well.

Distribution and habitat

Halocarpus bidwillii is endemic to New Zealand and grow from Coromandel to the extreme south; as the latitude increases, they are found at lower altitudes. In the North Island, it can be found in Taupo county near Rotoaira and in the central volcanic plateau and Kaingaroa plains. In the South Island, as the name implies, mountain pine are common in mountainous regions in Nelson, Canterbury, and Otago, with some plants found as high as 4,500 ft (1,400 m) above sea level in the Canterbury alps. Mountain pine can also be found on Stewart Island directly at sea level.

The mountain pine has a wide range of habitats, but mostly prefers montane to subalpine habitats from 39º latitude southward. Within its range, the annual average temperature is 8.5°C, the coldest month average minimum temperature is −0.8°C, and the annual average precipitation is 2,458 mm (2.458 m). In the North Island, mountain pine are found exclusively in montane to alpine habitats and usually between 600 and 1500 m elevation. However, mountain pine can also thrive in lowland conditions, and its presence on Stewart Island at sea level is an example of this. Mountain pine are also hardy plants growing in a wide range of ground conditions. Mountain pine can grow in both bog environments and in dry stony ground, with mountain pine growing extremely well in the Te Anau stony ground environment and just as effectively in wetland margins, frost flats, and riverbeds.

Mountain pine are one of the three most frost-resistant types of New Zealand conifers, and can typically resist frosts beyond −7 °C. Similarly resilient, mountain pine are often found in poor soils. True of many conifers, mountain pine actually prefer leached, low nutrient, and poorly drained soils, with many pollen diagrams showing that mountain pines thrive in infertile bogs. Although tolerant of frosts past −7 °C, mountain pines are typically found in environments with a mean annual temperature of 8.5 °C and an average minimum temperature of −0.8 °C. Mountain pine also live in environments that average 2,458 mm (2.458 m) of precipitation a year.

Ecology

Thriving without true fruits, the mountain pine has few predators which are mostly herbivorous insects. Briefly, the 4 main categories of insects that prey on mountain pine are: beetles, sucking bugs, caterpillars, and mites. Weevils, a specific type of beetle, feed on all Podocarpaceae (mountain pine's taxonomic family), and larvae thrive in any kind of decaying wood, including mountain pine. More specific, scale insects, Eriococcus dacrydii, live on the stems and leaf scales of the Halocarpus species, and even more specific, (Dugdale, 1996) found a species of conifer associated moth that uses the mountain pine as its host plant, appropriately named Chrysorthenches halocarpi. The caterpillars of Chrysorthenches halocarpi feed on the mountain pine shoots and when too many are present, the mountain pine appears bronze and growth can be stunted. Finally, Tuckerella flabellifera, red mites with white scales from Tasmania, live on young mountain pine plants and presumably feed on the young leaves and wood.

Phenology

Like all conifers, the mountain pine life cycle is dependent on cones. Male and female flowers are found on separate trees – male cones 3-5mm long are at the tips of branches and female flowers grow solo or in pairs and form just below the tips of the branches. From the time of seeding, male conifers will take about 2–3 years to reach maturity. When they have matured, male cones appear during the flowering season which runs from October to December, but most often occurs during October and November. Depending on the exact location, cone development can vary with North Island mountain pine producing cones more toward the October end of the range. By the end of November, the once juvenile reddish cones take on more brown character and begin to shed pollen. Around this same time, ovules grow at the tips of the branches and once fertilized by the pollen they develop a white aril at the base. Seeds begin to develop in the following months up until the fruiting season, which occurs from February to June. By February, green fruits mature, but do not ripen until mid to early March. Once they begin to ripen, fruits ripen quickly and take on a purple to black colour similar to the shade of an eggplant.

The seeds themselves are only 3-4mm long and have regular grooves stretching the length of the seed. Mountain pine can often be confused with closely related H. biformis, but a key difference between these 2 species' seeds is that mountain pine seeds are typically smaller and squatter than those of H. biformis.

Uses

When Kirk first described the mountain pine, he declared it to be of "little economic value" except perhaps for firewood. Perhaps he was unaware at the time, but Kirk should’ve specified that mountain pine could only be used for firewood without its bark. Mountain pine is one of the few New Zealand conifers that is able to resist fire, mostly because of its thick bark, but also because of its ability to recover through basal resprouting after a fire event. Other uses of the raw wood include timber production for use in buildings and railway sleepers.

Another potential use for mountain pine could be for decoration. Kirk commented on the "attractive character" of mountain pine, citing its symmetrical growth, and suggested that it could become an ornamental plant. Aside from decoration and perhaps firewood, no other uses of mountain pine or its products have been described to date.

Insecticidal activity

One trait of the mountain pine that is recently receiving academic attention, but has not yet been realized by the commercial sector is the use of mountain pine plant extract as an insecticide. Extracts of mountain pine foliage have shown the presence of organic compounds like diterpenes, phyllocladane and isophyllocladene and extracts of mountain pine leaves were shown to have been toxic to the codling moth, and partially toxic to the housefly. In these experiments milled leaf powders of several conifers (including the mountain pine) were incorporated into the diet of several insects and the mountain pine powder had over 75% mortality rate on the codling moths tested, and 55–75% mortality on the houseflies tested. Potentially toxic effects of mountain pine extract have also been studied in the germination of lettuce seeds. Foliage extracts from mountain pine significantly (p < 0.01) reduced germination when the extract came from both juvenile and adult pines, which did not differ from each other. Aside from germination, both juvenile and adult pines inhibited root hair growth. (Perry, 1995) hypothesized that these inhibitory effects of mountain pine might be due to allelopathic potential, since mountain pine often grow without any other vegetation below their shrubs. Further research is needed before mountain pine extract becomes of any commercial value.

References

Notes

1. This journal is now called the "Transactions and Proceedings of the Royal Society of New Zealand."

Citations

1. Farjon, A. (2013). "Halocarpus bidwillii". IUCN Red List of Threatened Species. 2013: e.T42478A2981942. doi:10.2305/IUCN.UK.2013-1.RLTS.T42478A2981942.en. Retrieved 12 November 2021.
2. "Assessment details for Halocarpus bidwillii (Kirk) Quinn". New Zealand Threat Classification System (NZTCS). Department of Conservation (New Zealand). 2017. Retrieved 15 September 2021.
3. "Flora of New Zealand – Taxon Profile – Halocarpus bidwillii". Flora of New Zealand. Landcare Research New Zealand. Retrieved 15 January 2016.
4. ^ Thomas, Kirk (1889). The forest flora of New Zealand. Govt. Printer. OCLC 223639237 – via the Internet Archive.
5. ^ de Lange, Peter (2014). "Halocarpus bidwillii". New Zealand Plant Conservation Network.
6. ^ Hayman, Alan R.; Weavers, Rex T. (January 1990). "Terpenes of foliage oils from Halocarpus bidwillii". Phytochemistry. 29 (10): 3157–3162. Bibcode:1990PChem..29.3157H. doi:10.1016/0031-9422(90)80178-j. ISSN 0031-9422.
7. ^ Webb, C. J. (Colin James) (2001). Seeds of New Zealand gymnosperms and dicotyledons. Manuka Press. ISBN 0958329931. OCLC 50704696.
8. Kirk, Thomas (1887). "A revised Arrangement of the New Zealand Species of Dacrydium, with Descriptions of new Species". Transactions and Proceedings of the New Zealand Institute. 10: 383–391 – via Papers Past.
9. Allan, H. H. (1961). Flora of New Zealand. Vol. 1. Lucy B. Moore, Elizabeth Edgar, A. J. Healy, C. J. Webb, W. R. Sykes. Wellington, N.Z.: Government Printer. p. 110. ISBN 0-477-01056-3. OCLC 80820075.
10. Quinn, Cj (1982). "Taxonomy of Dacrydium Sol. Ex Lamb. Emend. De Laub. (Podocarpaceae)". Australian Journal of Botany. 30 (3): 311. doi:10.1071/BT9820311. ISSN 0067-1924 – via CSIRO.
11. ^ Sinclair, W.T.; Mill, R.R.; Gardner, M.F.; Woltz, P.; Jaffré, T.; Preston, J.; Hollingsworth, M.L.; Ponge, A.; Möller, M. (1 September 2002). "Evolutionary relationships of the New Caledonian heterotrophic conifer, Parasitaxus usta (Podocarpaceae), inferred from chloroplast trn L-F intron/spacer and nuclear rDNA ITS2 sequences". Plant Systematics and Evolution. 233 (1–2): 79–104. Bibcode:2002PSyEv.233...79S. doi:10.1007/s00606-002-0199-8. ISSN 0378-2697. S2CID 25692189.
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13. ^ Quinn, C. J.; Price, R. A.; Gadek, P. A. (2002). "Familial Concepts and Relationships in the Conifer Based on rbcL and matK Sequence Comparisons". Kew Bulletin. 57 (3): 513. Bibcode:2002KewBu..57..513Q. doi:10.2307/4110984. JSTOR 4110984.
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15. ^ Biffin, Edward; Conran, John G.; Lowe, Andrew J. (2011). "Podocarp Evolution: A Molecular Phylogenetic Perspective". Smithsonian Contributions to Botany (95): 1–20. doi:10.5479/si.0081024X.95.1 (inactive 1 November 2024). hdl:10088/17172.{{cite journal}}: CS1 maint: DOI inactive as of November 2024 (link)
16. ^ Flora of New Zealand. Allan, H. H. (Harry Howard), 1882–1957., Moore, Lucy B., Edgar, Elizabeth., Healy, A. J. (Arthur John), 1917–2011., Webb, C. J. (Colin James), Sykes, W. R. (William Russell), 1927–. Wellington, N.Z.: Government Printer. 1961–2000. ISBN 0477010563. OCLC 80820075.{{cite book}}: CS1 maint: others (link)
17. ^ Biffin, E.; Brodribb, T. J.; Hill, R. S.; Thomas, P.; Lowe, A. J. (22 January 2012). "Leaf evolution in Southern Hemisphere conifers tracks the angiosperm ecological radiation". Proceedings of the Royal Society B: Biological Sciences. 279 (1727): 341–348. doi:10.1098/rspb.2011.0559. ISSN 0962-8452. PMC 3223667. PMID 21653584.
18. ^ Salmon, John T. (1996). The native trees of New Zealand (Rev. ed.). Auckland : Reed. ISBN 0790005034. OCLC 39106847.
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20. ^ Earle, Christopher J., ed. (2019). "Halocarpus bidwillii". The Gymnosperm Database.
21. Kuschel, G. (2003). Nemonychidae, Belidae, Brentidae (Insecta:Coleoptera:Curculionoidea). Manaaki Whenua-Landcare Research New Zealand Ltd. Lincoln, N.Z.: Manaaki Whenua Press, Landcare Research. ISBN 0478093489. OCLC 52819011.
22. Hoy, J.M. (1962). Eriococcidae (Homoptera: Coccoidea) of New Zealand. New Zealand: Department of Scientific and Industrial Research.
23. ^ Dugdale, J. S. (January 1996). "Chrysorthenchesnew genus, conifer-associated plutellid moths (Yponomeutoidea, Lepidoptera) in New Zealand and Australia". New Zealand Journal of Zoology. 23 (1): 33–59. doi:10.1080/03014223.1996.9518064. ISSN 0301-4223.
24. "Host Report With Reasons for Halocarpus bidwillii". Plant SyNZ. 2009.
25. Collyer, E (1969). "Two species of Tuckerella (Acarina: Tuckerellidae) from New Zealand". New Zealand Journal of Science. 12: 811–814.
26. Mabberley, D. J. (22 June 2017). Mabberley's plant-book : a portable dictionary of plants, their classification and uses. Cambridge University Press. ISBN 9781107115026. OCLC 982092200.
27. ^ Singh, Pritam; Fenemore, Peter G.; Dugdale, John S.; Russell, Graeme B. (June 1978). "The insecticidal activity of foliage from New Zealand conifers". Biochemical Systematics and Ecology. 6 (2): 103–106. Bibcode:1978BioSE...6..103S. doi:10.1016/0305-1978(78)90033-9.
28. ^ Perry, N. B.; Foster, L. M.; Jameson, P. E. (December 1995). "Effects of podocarp extracts on lettuce seed germination and seedling growth". New Zealand Journal of Botany. 33 (4): 565–568. Bibcode:1995NZJB...33..565P. doi:10.1080/0028825X.1995.10410629. ISSN 0028-825X.

External links

• Gymnosperm Database: Halocarpus bidwillii

• IUCN Red List least concern species
• Trees of New Zealand
• Least concern plants
• Podocarpaceae
• Endemic flora of New Zealand