Early October and one of the complaints about native plants is put to the sword. Lots of people say that natives do not have very colourful flowers, but a quick look around at this time of the year quickly dispels that notion.
The Head Gardener and I were part of a tour to north Wairarapa last week and called into Pūkaha for a cup of tea on the way home. Sitting out on the deck and watching the takahe in the enclosure below, we were captivated by a nearby kōwhai tree whose flowers managed to attract a warbling tui, a couple of bumblebees and even a kahukura, a native red admiral butterfly. Not a kereru though!
There is no doubt that a kōwhai tree in full blossom is as attractive a tree as you are likely to see, the bright splash of yellow flowers bringing lots of colour to many gardens.
There are many different species of kōwhai in New Zealand, including a couple of overseas species that have been accidentally introduced to our environment. Some years ago, a collection of different kōwhai was made to assess the potential of various cultivars for introduction. Although not many New Zealanders know this, there are “kōwhai” found across the Pacific and in South America.
At one stage, one nice form was selected for introduction and distributed through the nursery trade as a cultivar of the native species Sophora microphylla. Although it is similar, this plant was in fact the Chilean species S. cassioides. It has since been recorded as jumping over the garden fence and establishing in the wild.
There are officially eight indigenous species of kōwhai, including one only found on coastal areas near Cook Strait – S. molloyi, a smaller growing species that flowers very early. We have one in our garden that usually flowers in June but it can have blossoms as early as April.
It is very hardy. I once pruned our plant back to ground level, thinking I would remove it, but within weeks it had sprouted anew and I did not have the heart to take it out. It grows to about head height but does spread out a little. It is a great plant to have in a sheltered spot.
If you like divaricating plants [the Head Gardener hates them and complains if I plant one] then the dwarf or prostrate kōwhai, S. prostrata, is the one to select. This is found wild on the east coast of the South Island, most plentifully around Banks Peninsular, and has tiny leaves carried on crisscrossing branches.
When grown from seed, most kōwhais start out with this divaricating growth, but they soon outgrow the habit. This species retains it making it unique among kōwhai. The flowers are quite small and are also very different in colour. The “yellow” flowers are much deeper than other species – in some cases they are almost orange.
As well as having small flowers, the overall growth of this species is usually quite constrained too. In some cases, the plants are, as the name suggests, prostrate, but more usually they are small shrubs, growing to about two metres.
Interestingly this species has another unusual trait – the seeds are very dark in colour, as opposed to the more usually golden yellow of the other species. They can be dark brown or even black. It is definitely one to look out for.
Most people who have a kōwhai in the garden will report that they end up with more than one, as some of the species are very good at producing masses of seed, and some of the seed usually germinates. If you are looking to do it in a more controlled manner. It is best to chit the seed [taking a small nick out of the hard shell] and soak it in hot water for a minute or two before sowing. You can also propagate from tip cuttings taken at this time of the year, a sure way to make sure the new plant you get is identical to the parent one.
You will sometimes read that all parts of the kōwhai are poisonous, especially the seeds. Apparently, you would need to eat a lot of any part of the kōwhai for it to have a bad effect, and there have been no reports of humans being badly affected by it. However, I did read about a case where a horse was given its hard feed on the ground underneath kōwhai tree, and apparently there were a lot of seeds eaten with the feed which caused the horse some discomfort. Fortunately, removal from the paddock soon had the horse returned to good health.
Having had a family member who was keen on eating anything she could find in the garden when she was young – she had a couple of trips to the hospital as a result – I think it probably pays to be a little bit careful about planting kōwhai if you have such a child.
