Carnivorous plant collector Cor Schipper
As a young boy in the Netherlands, Cor Schipper's class was shown a carnivorous sundew plant by his teacher – and it sparked a lifelong passion for the retired entomologist.
Cor, now 80, and wife Hetty left their homeland in 1963, living in Australia and Samoa before coming to New Zealand and, after a stint in Wellington, settling in Rotorua in 1971.
Cor has always been interested in the natural world, so it's perhaps not surprising that his hobbies and work – mass-breeding insects for research and working on biological controls – sometimes overlapped. For example, his collection of bromeliads, which began in Holland, was thanks to a gift of tropical frogs – it turned out they would lay eggs only in a bromeliad.
Although he had sundews in Holland, his interest in carnivorous plants was realised when he came to New Zealand. Listening to Cor describe the mechanisms used to trap prey – primarily scent, colour and nectar – it's easy to see why he finds them so fascinating.
But why have these plants evolved in such a striking fashion? Although they can be found in a wide variety of climates and elevations in many different countries, they all have one thing in common. Carnivorous plants grow in nutrient-poor soils or water-logged conditions – so they need to extract minerals and nutrients for growth from another source. A living source.
Another common feature is long-stemmed flowers, reaching well above the plant, to protect pollinators from falling victim to their deadly "charms".
Sarracenia (pitcher plants), which are found in boggy areas of the eastern United States, "dope" their nectar with coniine, a chemical found in hemlock. "If you put the nectar in a petri dish with ants, the ants go all wobbly," Cor says. "The hairs of the Sarracenia tube face downwards to guide the ants down, then there's a slippery patch on the tube wall so they fall into the liquid at the bottom. The liquid has a surface like soapy water, so instead of floating the ants fall straight through, and the chemicals in the liquid take care of the body."
A Venus flytrap (Dionaea muscipula) won't react if the hairs inside the hinged trap are touched only once. Touch them twice, however, and it snaps shut in a fraction of a second. "The plant wants nitrogen, phosphate and potassium so it removes the enzymes it needs from its prey but leaves the exoskeleton. When the process is finished the trap opens, ready for the body to wash out in rain." Don't be tempted to set the traps off yourself though – do it more than twice on the same trap and it will likely die.
Nepenthes lowii, a pitcher plant vine from Borneo, exudes a sweet, fatty substance in order to attract small mammals – but not to consume them. As the animals feed, they excrete into the pitcher and in doing so feed the plant.
"The variety of carnivorous plants is astonishing," Cor says. "In the Nepenthes family alone there are well over 100 species, with pitchers that range in size from 3cm long and specialise in catching insect-bearing compost falling from trees, to Nepenthes rajah, the largest carnivorous plant in the world, which has pitchers the size of a rugby ball."
Although most Nepenthes attract ants, there is one that attracts termites too and some can even digest small rats and shrews if they happen to fall in. "That generally happens during a dry period when animals come to drink from the pitchers but are a bit weak and fall in."
One of the most fascinating carnivorous plants, in Cor's view, is also one of the smallest. The rootless Genlisea family (corkscrew plants) set their traps underground. They're semi-aquatic and grow in moss or mud. Although it has leaves above, there are also modified leaves extending below the plant. Each "leaf" has forked, hollow spirals that exude a chemical to attract prey. The prey climbs up the spiral with the hairs growing upward to guide it.
"In Brazil in the past five years they've found Philcoxia minensis, a carnivorous plant that flowers above the soil but keeps all its sticky leaves underground, where it catches nematodes."
Over the years Cor has done some of his own breeding, particularly of Sarracenias. "I've been working on one for about 25 years, but when you work on your own it's not always done as scientifically as it should be in terms of record keeping. I lose patience sometimes."
Living on a hill above Rotorua, his home cops some decent frosts but the Sarracenias and Venus flytraps stay outside year-round. "They can both freeze but will come back in the spring, no problem," he says. "And most of the sundews have a winter dormancy, although Drosera auriculata, a New Zealand native, has a summer dormancy. There's a huge temperature-tolerance variation among all the families so it's worth researching – for instance, most Nepenthes are tropical and need to be kept inside but there's one from a mountain in New Guinea that can stand a bit of frost."
His rare Darlingtonia californica, still a tiny plant, requires special attention. Closely related to Sarracenias, it grows only in northern California and Oregon on the sides of streams fed by meltwater. "It's very difficult to grow because it likes warm leaves and cool roots, maybe a difference of 15°C. I have to feed it ice cubes every day."
Unfortunately, Cor says carnivorous plants aren't the answer to a garden's whitefly, ant or mosquito problem. "Research has shown they collect only about 5 per cent of what's around, so they're not a great biological control – instead, enjoy them as another example of nature's wonder."
Where to buy:
Cor Schipper (07 348 4362) has a couple of thousand Sarracenias plus multiples of other types.
Ross Taylor owns Carnivorous Plant Nurseries in Geraldine; call 027 547 0301 for more information.
Look for plants on Trade Me.
The NZ Carnivorous Plant Society is no longer active.
- NZ Gardener