From a distance as you approach the islands from the west they appear to be covered almost entirely with Pohutukawa, Metrosideros excelsa. As you move closer you can see the caves and pitted cliffs where in any crevice wide enough to hold the smallest amount of soil plants will take hold, coastal tussock (Chinochloa brommoides), ice plant (Disphyma), flax (Phormium tenax), renga renga lily (Arthropodium cirratum), Coprosma repens and higher up poor Knights Lilies (Xeronema callistemon) perching on outcrops.
On the eastern side of Aorangi is the only shore line of any substance, known as “the beach” by weeding parties. Inland is lush subtropical broadleaf forest. According to the published papers of de Lange and Cameron in the New Zealand Journal of Botany 1999, the number of vascular flora of the island group at 276 species, with possibly only one plant endemic to the islands. However they also conclude that many are near endemics. Their close proximity to the coast prevailing westerly winds and being within reach of foraging birds effectively prevents the genetic isolation of the Poor Knights flora.
It would be fair to say that the islands broadleaf plants have larger, glossier leaves than their mainland counterparts a phenomenon commonly known as “Island giantism”, possibly caused be highly fertile soils continuously enriched by millions of seabirds which nest there, but a more accepted theory is the fact that the islands escaped the cold of the last ice age assisted by the warm waters of the east Auckland current which just graze the islands before heading back out to sea.
The first botanist to publish an account was Cockayne in 1905. He landed briefly on Aorangi for two to three hours. Although he missed the Poor Knights Lily he did discover a large population of Carmichaelia williamsii (giant flowering broom). Pigs were still running wild during Cockaynes visit. What he described as grasslands is now covered in thick growth up to six meters high.
Poor Knights Lily or Taranga raupo still a comparatively rare plant in cultivation would have to be one of New Zealand’s finest horticultural plants.
(Muriel Fishers book Gardening with New Zealand Plants). In 1924 another NZ botanist Oliver along with Fraser a Whangarei Harbor Engineer collected material of Xeronema (Poor Knights Lily) Mr. Fraser knew of this plant from Maori tradition. Xeronema had been known only by Xeronema moorei growing at about 5000 feet up in the inland mountains of New Caledonia. In spite of the great difference in their environment the two plants bear many similarities. I know of only one place on the islands were the Poor Knights Lily comes close to the sea they are found growing mostly near or at the top of the islands perhaps a link to a higher attitude past and the reason Cockcayne did not notice them in 1905.
This is a slow growing plant; our first attempts at growing this plant were dismal. In fact, we probably killed more plants than we grew. It wasn’t until after several visits to the islands that we had success. It seems that although large plants can be found growing perched on rocks on cliff edges basking in full sun and wind. In cultivation they respond much better to semi shade areas. In fact the largest plants with their sword-like leaves, up to 1.8 meters high, are under the canopy of large Pohutukawa. Sometimes growing in the forks of branches where the native parakeet hollows out nests at the base of the plants. They need good air movement and perfect drainage and after a number of years 8-10 maybe you can expect some spectacular flowers.
Perhaps the most successful Poor Knights plant in cultivation is the Arthropodium or renga renga lily. This plant was introduced into cultivation by Malcolm Woolmore of Lyndale liners. Although named Matapouri Bay I am no doubt that its origins lie at the Poor Knights. Malcolm spotted it in our neighbor’s garden. These people being passionate gardeners and great sailors often brought plant material back from the islands. They would pull up to the islands scramble ashore pull or push large bits of vegetation off throwing them on to the deck of the boat. A nephew told me that as kids they would have a great time catching the lizards and strange insects that crawled out of the vegetation as it hit the deck.
The Poor Knights renga renga has an unusually robust habitat, larger leaves and larger than usual showy flowers.
There are a number of other Poor Knights plants appearing in cultivation Mrysine Poor Knights makes an excellent alternative to buxes. Coprosma repens, a very prostrate form is fantastic for covering bare clay banks. Auckland zoo has used this plant extensively through out the zoo’s new enclosures along with Poor Knights Muehlenbeckia complexa.
Noticeable is the almost complete lack of podocarp trees or any of the large conifer forest trees. During our weeding surveys one small Totara tree was discovered and a number of young Kauri trees. One tree was large enough to wrap your arms around. While it is easy to understand how a bird could deposit seeds from a Totara tree it is harder to understand how a number of Kauri seeds could blow from the mainland. Perhaps the islands greatest contribution to the New Zealand’s flora is the preservation of some of our rarest and endangered plant species, provided that the islands remain weed and rodent free there is no reason for this to change.
Guy & Sandra Bowden are owners of Tawapou Coastal Natives Plant Nursery on the Tutukaka Coast. Guy grew up on the Tutukaka Coast and has been passionate about NZ native plants all his life. His interest was kindled by his conservationist parents who began protecting sections of native bush and pohutukaka on the cliffs of the property over forty years ago. Below Guy talks about The Poor Knights Islands in relation to location & geology; history; plants and birds on the islands; reptiles, insects and snails on the islands; marine life and the 1996 weed eradication programme.