#lancewood

AKA fierce lancewood or horoeka.

And similar to the more common Pseudopanax crassifolius, that I covered for @purrdence's last visit, but with more prominently tooth-edged leaves. The juvenile leaves are narrow, a very dark grey-brown to grey-green colour, stiff and up to 40 cm long, and prominently toothed along the margins. This may have evolved to make them visibly and texturally unpalatable to Moa. After 10 to 15 years they transition to a much more normal-looking tree, now their foliage is out of reach to even the tallest giant flightless birds.

A mature toothed lancewood can be 6 metres tall with a trunk of 25 cm in diameter. The mature trunk has longitudinal grooves which sometimes twist slightly.

Increasingly popular as a small garden tree.

Other species of Pseudapanax are very different, as you'll see over coming weeks.

Plant of the Day

Friday 20 December 2019

The long, bronze evergreen leaves of Pseudopanax ferox (toothed lancewood) have a jagged edge which evolved to protect the plant from grazing animals. The narrow leaves radiate from a thin trunk in the juvenile phase while mature plants produce shorter, spreading, dark green leaves. This amazing New Zealand plant in the mature phase produces umbels of green-white, star-shaped flowers with black berries on the female plants. 

Here’s an odd one

After getting across Cook Strait without being shipwrecked (the weather was actually quite pleasant compared to some of the unholy gales that come through the gap, with the wind merely howling), we started our explorations of Te Waipounamu, the Island of Greenstone Waters. Pounamu is such a beautiful and useful stone that the Māori named the entire island after it.

Europeans called it South Island, or archaically New Munster. It covers 150,437 square kilometres, making it the world's 12th-largest island. We stopped at the Omaka Aviation Museum, which was worth it, but our first night was spent at St. Arnaud, formerly Rotoiti, a tiny alpine village.

It's certainly surrounded by mountains, and shows some really nice alpine geomorphology - hanging valleys left where subsiduary glaciers got cut off by the larger glaciers in the main valley, scree slopes where the greywacke of the mountains is disintigrating, and alpine lakes like Lake Rotoiti itself, formed when the glaciers retreated at the end of the last Ice Age and left behind huge piles of pebbles, gravel, and boulders to dam the meltwater.

On the other hand St. Arnaud has also been built right on top of a considerably larger geological feature - the Alpine Fault. This tectonic boundary between the Australian and Pacific Plates runs for over 600km, and is one of the fastest moving faultlines in the world, moving, on average, almost 40mm a year. Geological formations that originally straddled the fault are now 480km apart. Unfortunately most of that movement happens during huge earthquakes every few hundred years - the last big one on the Alpine Fault happens around 1717, rupturing 400km of the fault at once.

Over the last 12 million years a significant upwards element to the fault movement has been added, creating the Southern Alps. Most of what is now the South Island got pushed 20 kilometers up, whereupon New Zealand's weather promptly ground it 16 kilometers back down again. The assorted rubble forms the plains on the east and southern coast, or got swept north by prevailing currents on the west coast. Exposed basement rock on the South Island is mostly greywacke, or heavily metamorphised rocks such as schist from even deeper. That's where the greenstone originally formed.

Anyway, the next big quake will probably trash St. Arnaud completely, and cut every road across the mountains for months. Happily that didn't happen on this trip - @purrdence had enough problems with a cyclone cutting roads and trainlines last time.

The original forest around St. Arnaud is mostly Antarctic Beech (Nothofagus sp.) and forms the basis of a unique and seriously threatened ecosystem. I'll tell you all about that over the upcoming posts.

Here's some species I've covered before.

After Pohokura we spent a couple of days on the west coast of North Island - specifically, in the vicinity of Taranaki/Mt. Egmont, a young stratovolcano that is the most recent volcano in a long sequence of slowly migrating volcanism in the area. The hills to the northwest, and the plugs at the coast at New Plymouth, are all that remain of its predecessors. In fact, the entire ring of flattish and highly fertile land in Taranaki is the result of the repeated catastrophic collapse of the volcanoes over the last 1.75 million years.

The photo below was taken from Cape Egmont 30 kilometers from the volcano. Even out here there are layers of fridge-sized boulders deposited by the giant volcanic landslides.

The plugs at New Plymouth, 1.75 myo.

Historically, the area consisted of a narrow coastal plain covered by bracken, tutu, rewarewa and karaka trees, with anywhere not close to the coast covered in dense forest.

From about 1823 the Māori began having contact with European whalers and flax traders. English settlers were first dropped here in 1841, and within a year were trying to deal with plagues of the rats they brought with them.

The stuff we saw on the volcano itself I'll cover seperately, but there was no shortage of species in New Plymouth, along the coast, at Lake Mangamahoe, and where we were staying.

Photo by @purrdence​, at Rotorua in NZ

AKA horoeka. The binomial means ‘thick-leaved false ginseng’, and the common name presumably refers to one traditional use for the long straight juvenile trunk.

A New Zealand native tree in the family Araliaceae, where it grows from the coast up to about 750m with a few relatives around the islands.

Most noteworthy for the drastic change in form from juvenile to mature tree - this one is a juvenile. When these plants were first described, the juvenile form and the adult form were thought to be different species. The leaves are brown, serrated, up to a meter long, and look pretty much dead. 20 years later the trunk begins to branch, producing a bushy top, and the leaves become wider and shorter losing their teeth, and more closely resembles a normal tree, up to 25m tall. 

One theory is that the young plant had to protect itself against browsing by the giant flightless Moa birds, wiped out by the first humans to settle New Zealand. Once above Moa height, it was out of danger and turns into a "regular" tree. The closely related Chatham Island species does not display these changes, but the Chathams didn’t have Moa.

Grown as an unusual ornamental in cooler parts of the world, although you might get questions about why you haven’t removed a dead plant. Their best known relative is English Ivy, and the flowers are very similar. In fact, lancewoods frequently grow as epiphytes themselves.