Tropical wonderland

On up the Huatoki - it sounds like a chapter heading for an adventure story, shades of the Zambezi or the Orinoco. It might be true, for some of the tropical plants along the way would be quite at home on those two rivers.

Last week, we ended the walk at Redcoat Lane and we begin there this week, turning left after the bridge and heading inland.

Very soon we're among our own tropical natives trees - the puriri and karaka.

These two fine species are a good enticement to enter the walkway and they have a botanical link to the tropics.

Both puriri and karaka, as well as kohekohe and pukatea, are supposedly the remnants of a time when New Zealand was closer to the tropics and part of a primeval land mass.

They have the buttress trunks associated with tropical trees today. The close relatives of these trees live in steamy places like Malaysia.

There are tropical weeds too: South African plectranthus, Himalayan wild ginger and Peruvian tropaeolum or nasturtium growing on the banks, sometimes carpeting huge areas.

Look to the top of the nasturtium bank along on the right, where you will see a shrub with weird fluffy flowers like balls of cotton. This is a legume called Calliandra haematocephala and they come in pink and red versions too, which explains the name - the "haema" bit means blood-red.

We tend to think of tropical plants having huge leaves, but this is a hot-loving jungle plant with very dainty feathery foliage.

A bit further on, look left across the river and see how devastating the morning glory can be, growing right over the tops of big trees.

Most of us find the glowing, purple-blue flowers irresistible, but when you see it strangling trees like this, you realise it's not a plant to relish.

Down below, growing in the shade next to the river, is a giant hibiscus with upright vigorous stems and huge, hand-like leaves.

I'm still trying to work out what this is. My best guess is that it's Abelmoschus moschatus, from India, but I'm open to suggestions.

The walkway now reaches out into more open land on a river flat, with signs of quarrying and road-repair shingle.

Then out in the sunshine are a whole lot of gum trees on the right, part of the prison complex.

The track is like a highway now and all around are weeds, but somehow they look attractive.

There are self-sown native shrubs like coprosma, peppers and whiteywood, as well as exotics like fennel and purple castor-oil plants.

Even Oldham's bamboo is a weed, but it is handy for making pea sticks or tomato canes.

Despite being weeds, they look good and fill a niche. The ginger is the worst weed, because the birds eat and distribute the red seeds.

To a finicky gardener, the whole walkway is full of weeds, but apart from the ginger and morning glory, I don't have a problem with them, because they all look good in their way.

If we wanted to eliminate the weeds and replace them with acceptable plants, it would take a team of 10 gardeners, and I don't think ratepayers would be happy.

The walkway is a recreational facility, somewhere to stroll or jog, or a shortcut to town.

Our river walkways serve several other purposes: first, as somewhere to funnel stormwater and reduce the risk of flooding; then they are used as routes for sewerage pipes on public land, avoiding the need to dig up people's gardens or too much of our roadways.

Near the middle of the big open area is a group of Agapanthus 'Storm Cloud'. It's such a good name for this plant, because the flowers are purple black, just like a threatening sky.

You're now right out in the open in what used to be a quarry.

On the far side, almost into shade again, look across the stream to see a white hydrangea and a very odd tree with round, nuggety balls of fruit and thumb- sized evergreen leaves, a semitropical Aussie native known as turpentine tree or Syncarpia glomulifera. It is renowned for amazingly hard and durable timber, ideal for making wharves.

Now back into the shade and a white fence on the left. Across the stream is a tropical legume tree, the elegant Acacia elata. The lemon, fluffy flowers give the clue to what it is, but the foliage is the best feature. Apparently it's a good timber tree, but grown here as a handsome exotic.

Soon you'll find yourself in Harris St, named after an early city surveyor. Just on the left is a really old-fashioned hydrangea with waxy petals like cake decorations. The rounded heads are much smaller than usual and about the size of a clenched fist.

This ancient Japanese variety is called 'Ayesha' and it's one of the best for growing in hot sun, or in windy places, because it has very glossy leaves. As a general rule, the glossier a hydrangea's leaf is, the better it will cope with wind and sun.

The first 'Ayesha' bush you see here has rich, blue flowers, but a few metres up the track another one has pink blooms.

In general, it's hard to achieve pink or red-blooming hydrangeas in Taranaki, because the soil is acid and rich in aluminium, which turns them blue or purple.

The easiest way to achieve reds is to grow them in tubs or pots, where it's impossible for the roots to get any aluminium. Adding lime or phosphate will make them red, as both lock up the aluminium and make it unavailable to the plant.

Although hydrangeas are not quite tropical, they could fit a tropical theme in a garden, with their bold leaves and huge, everlasting flowerheads.

But many of the plants we've seen today are semi-tropical, and while it's not quite the Orinoco, we certainly saw plenty of lush, exotic plants, and no snakes.

My thanks to Alan Jellyman.

Taranaki Daily News