The Poor Knights Lily, or Raupo Taranga, Xeronema, is one of our finest flowering plants and ranks as one of our best horticultural subjects.
A genus of just two: Xeronema morrei, growing at about 5,000 feet up in the inland mountains of New Caledonia, and Xeronema callistemon, confined to the Poor Knights and Hen Islands off the Whangarei coast.
Although a colony of lilies is growing on an inland rock face on Taranga or Hen Island, the geology of the Poor Knights would suggest that group is its original home.
The Poor Knights have been isolated from mainland New Zealand for longer than any other island group apart from the Three Kings Islands 60 km northwest of Cape Reinga. What remains today of the Poor Knights are the heavily eroded rings of a large volcano that erupted some 10 million years ago. This volcano was possibly 1,000 metres high, measuring 15-25 kilometres in diameter.
The first botanist to publish an account of the island plants was Cockayne in 1905. He landed briefly for 2 to 3 hours on Aorangi, the smaller of the two main islands in the Poor Knights group. Although he missed finding the Poor Knights Lily he did discover other rare and unfamiliar plants.
I know of only one place on the islands where the Poor Knights Lily comes close to the sea. Most are found growing near the top of the islands, perhaps a link to a higher altitude past and no doubt the reason Cockayne did not notice them in 1905. It wasn't until 1924 that another NZ botanist, Oliver, collected material of the Xeronema.
From the 1924 expedition two Poor Knights Lily plants were brought back and given to the late Mrs A. R Pickmere of Whangarei and in 1932 these plants flowered, supposedly the first flowering of a Poor Knights Lily on the mainland. These two have been divided many times but I understand the original plants are still growing in the garden of the Pickmere Homestead in Hatea Drive.
Another very old plant is growing in the grounds of Pompallier House in Russell. This one was brought back to the mainland in 1929 by Captain Bollins of the government survey ship 'Tutanekai'.
Although large plants growing on the islands can be found perched on cliff edges basking in full sun and wind, in fact, the largest plants with their sword like leaves, up to 1.5 metres high, are under the canopy of large Pohutukawa. These plants also benefit from highly fertile soils continuously enriched by the millions of seabirds which nest there. They can also be found growing in the forks and branches of trees where the native parakeet, the kakariki, hollows out nests at the base of the plants.
They can also be found growing in the forks and branches of trees where the native parakeet, the kakariki, hollows out nests at the base of the plants.Guy Bowden
On the Poor Knights reptiles play a huge role in the ecology of the forests. There are as many lizards as there are forest birds and at night you can see geckos pollinating Xeronema flowers in the same way birds would do. It seems that in cultivation the plant prefers semi-shade.
Xeronema is more than just a collectors item. Its sword like leaves make it a handsome, structural plant at any time. When grown from seed in cultivation you would have to consider them very slow moving. After two years they are around 80mm high.
However, once four or five years old, growth is much faster although it can still take another five years before they send out an amazing flower stalk with a stunning bottlebrush red flower. Xeronema make wonderful pot plants but should never be put into a pot too large for the plant. It is much better to repot them over time to increase the plant size.
Plants need perfect drainage and will not tolerate boggy conditions. Being frost tender they need a warm situation where they get either the morning sun or the afternoon sun, not all day sun. Good air movement is also important. Regular feeding with an organic seaweed or fish fertilizer will produce good results and maintain a good healthy plant.
Found only on the offshore islands so close to our city is a plant that Whanagrei should have claimed as an icon for street plantings. A number of good examples of Xeronema plantings can be seen in the streets of Auckland and Devonport. New Plymouth also has planted hundreds of Xeronema throughout the city and outlying towns. Many of these plantings make a spectacular flowering display in spring.
Why do we have a meaningless mixture of subtropical foreign plants around Forum North, our cultural centre, Library and in our Mall instead of our own unique Northland treasure?
The trick to healthy Poor Knights Lilies
Poor Knights Lilies are very susceptible to root rot diseases and over the years that we have been growing them a number of our customers have been very disappointed to loose their treasured lilies to these root diseases.
There is a simple and effective cure called Phosphorous acid and potassium salts, which is a product that originally started its life as a fertiliser and was then found to be very effective in controlling Phytophthora in avocados. It is marketed under the trade name Phoschek or Folia fos.
First carefully remove any infected plant material and destroy it, whilst being careful not to contaminate any other part of the plant with this infected material.
Even if your plant does not show signs of rot it can also be used as a fertiliser.
Then apply Phosphorous acid to your lilies with a watering can at the recommended rate, drenching the whole plant, leaves and soil.Even if your plant does not show signs of rot it can also be used as a fertiliser.
There is no harm using this chemical at any time whether there is sign of disease or not. As the acid started its life as a fertiliser we have found it improves the general health of our lilies.