Tree of the moment: Pinus radiata

Yes, the most common – at least in New Zealand – of pine trees, but every tree has a story and a sign at the Wellington Botanic Gardens got me thinking about how little I know of Pinus radiata, the tree we grow in massive forest blocks for timber, the wood and cones we burn on our fires, the scent we love at Christmas time.

The government asked Sir James Hector, the garden’s first manager, to source conifers with the best economic potential. By 1884 he had imported (no biosecurity restrictions) and trialled 127 species. The most successful then, and now, were Pinus radiata (Monterey pine) and Cupressus macrocarpa (Monterey cypress or macrocarpa). Both  are native to coastal California and – despite growing like Topsy here – both are endangered in their native habitat.

Wellington Botanic Garden is home to some of the oldest Pinus radiata in the country – a stand planted in 1871. Photo: Sandra Simpson

Albert Kellogg, a San Francisco doctor and botanist, alone sent more than 25kg of wild-collected Pinus radiata seed to Wellington, meaning the genetic diversity of the garden’s trees was high – and from stock long gone in its native area.

Seed and seedlings from the garden were sent all over New Zealand, half a million between 1870 and 1875, and DNA tests show that some of the ancestors of our forestry industry came from Wellington Botanic Garden. The oldest tree in the country is believed to have been planted in 1859 at Mt Peel Station in South Canterbury.

Pinus radiata makes up 90% of our forestry plantings but Te Ara Encyclopaedia of New Zealand says foresters had to learn how to manage the tree as it wasn’t used for forestry in California and, in fact, wasn’t widely grown there. Read the rest of the entry here.

Read a NZ Geographic profile of Pinus radiata by Chris Hegan.

Swan plant sagas

Seen at work in my garden this week …

Ladybirds attack a patch of oleander aphids. Photo: Sandra Simpson

Here’s what you need to know about these yellow aphids and yes, that is a swan plant they’re on. I had been using digital control until I saw a ladybird or two about and reckoned I needed to back off to let my spotty helpers take charge.

This article has some ideas about how to control aphids on milkweeds (which a swan plant is) and not upset eggs or caterpillars.

Unfortunately, ladybirds will also eat butterfly eggs and young caterpillars … aargh. The poor butterflies can’t win, although in better news last evening I saw two FAT caterpillars munching away on the swan plant so some eggs are surviving.

Here’s a great few photos of a monarch’s life cycle by George Novak, a Bay of Plenty Times/freelance photographer who loves photographing the natural world. George was responsible for some of the brilliant native orchid photos in NZ Geographic (November-December 2013).

I’ve also found yellow aphids on the growing tips of two hoya plants, but they are easily controlled by squashing.