There are over 160 species of Drosera, or sundews as they are commonly called, found throughout the world; the greater percentage of them are found in Australia. New Zealand only has 7 Drosera species, most of which also grow in Australia. Sundews principally inhabit areas that are wet or boggy for at least part of the year.

Trapping Mechanism -

All species employ sticky gland tipped hairs (tentacles) to capture and devour their insect prey. These hairs usually occur around the periphery of the leaf lamina and on its upper surface. They are sensitive to both touch and taste. An insect struggling to escape the sticky mucilage stimulates the tentacles to inflex, carrying the hapless victim to the centre of the lamina where more glands await. The insect is quickly subdued while the secreted digestive enzymes begin breaking down its body. The resulting digested products are reabsorbed by the lamina and the whole process is complete within a few days leaving behind only a husk. The tentacles resume their original positions, ready for their next meal.

Sundews come in many different shapes and sizes. Below are listed the types which occur in New Zealand.

Rosetted Sundews -

As the name suggests these species form a rosette of leaves at ground level. The leaves themselves may be held flat on the ground or at any angle to almost vertical, depending upon the particular species. Most species measure more than 2cm in diameter. They often grow in habitats that are constantly wet and some may even revert to a resting bud (hibernaculum) to survive harsh winters.

Pygmy Sundews -

These are the smallest of the sundews with most species measuring less than 2cm across and have tiny leaves which catch comparatively tiny insects. At the centre of the rosette is a stiff cone of stipules, which they use to protect the growing point from harsh summer temperatures. They are notable for producing asexual vegetative buds (gemmae) as a means of propagation during autumn and in some species their flower may be larger than the diameter of the plant itself. The greatest proportion of them occur in Western Australia.

Cormous Sundews -

These species grow in winter-wet / summer-dry habitats and grow from underground corms. They come in basically 2 forms - those that form rosettes and those that form climbing stems that can grow up to 2m tall (depending upon the particular species). They appear on the surface in late autumn/early winter shortly after the first heavy rains. They quickly grow to full size and usually flower in early-late spring. After flowering they quickly die off and survive the dry summer soil as a small pea-sized corm several centimetres below the surface. The greatest proportion of these too occur in Western Australia.

Descriptions and photographs of our native sundews can be found by following the links below.

There are over 200 species of Utricularia, or bladderworts as they are commonly called, in the world; the greater percentage of them are found in South America with Australia coming a close second. New Zealand only has 5 species, most of which also grow in Australia. Bladderworts principally inhabit terrestrial areas that are wet or boggy for at least part of the year and also occur in fully aquatic environments.

Trapping Mechanism -

The traps of Utricularia resemble tiny ovoid bladder-like sacs that usually arise from the stolons and other underground parts. In most species they are less than 2mm long. When the trap is set the sides are concave and a vacuum is formed within. A passing tiny insect triggers a trap-door which springs open within an instant sucking the prey inside the bladder along with water and sometimes other debris. The door snaps shut and the hapless insect is imprisoned. Digestive enzymes are now secreted and the prey is consumed over several days. After a trap has been triggered its sides are now convex and it has to pump out the excess water in order to reset; ready for its next meal.

Bladderworts come in many different shapes and sizes. Below are listed the types which occur in New Zealand.

Terrestrial Bladderworts -

As the name suggests these species (the commonest type) live on land and inhabit places that are wet for at least part of the year. They have slender underground stolons that give rise to tiny grass-like leaves and may eventually form extensive mats if conditions are suitable. They generally flower in summer and the small centimetre-sized flowers can be quite pretty. Most are also self-fertile and produce copious quantities of seed making some very weedy in cultivation. Those species growing in cold habitats may loose their leaves in winter and survive beneath the surface as stolons.

Aquatic Bladderworts -

As the name suggests these species are almost wholly aquatic and are found living in the still waters of lakes and ponds. They normally float near the surface growing as long leafy strands and some may attain several metres in length; still others can form extensive filamentous mats. Their habitats can sometimes temporarily dry out in summer which can trigger mass flowering of some species or cause others to revert to buds (turions) in order to survive desiccation. Those species growing in cold climates have adapted to winter conditions by reverting to turions as growing conditions become less favourable. Portions of plants are easily transported to new habitats by waterfowl (sometimes over considerable distances) and often a particular species may occur at many locations along the flight paths of migratory wading birds.

Descriptions and photographs of our native bladderworts can be found by following the links below.