AMONG the plants that really impressed me in the tropical green house known as the Princess of Wales Conservatory at the Kew Gardens in London were the giant Amazonian water lilies, peppers, bananas and pineapples. However, it was carnivorous plants such as the Titan arum, with its foul stench and rare flowering, that caught my attention.
TALL VARIETY: Utricularia macrorhiza can grow up to eight inches in height.
I was particularly pleased to find the as bladderworts, which are also grown in Malaysia. Bladderworts can be divided according to their habitats – floating aquatic, semi-aquatic, terrestrial and lithophytes or low epiphytes.
At first, these look like just tiny weeds on the water that are not very interesting. However, like pitcher plants, bladderworts are carnivorous and have the ability to get nutrients for food by trapping prey.
They belong to a genus called Utricularia and the family Lentibulariaceae. There are more than 220 species capable of trapping insect larvae, aquatic worms, water fleas, and other small water creatures including tadpoles and fish fry!
Early understanding
Wort is an old English word for plant. The bladderwort got its name from the tiny bladder-like structure of its leaf-branches.
Early in 1875, British botanist Alfred Russell Wallace – author of ‘Sarawak Law 1855’ – wrote to Charles Darwin on bladderworts. The latter was amazed to find that the plant was perfectly designed to trap prey.
Even today, these little plants still fascinate me and all nature lovers alike.
Sophisticated engineering
The bladderwort’s trap door is recognised as one of the most sophisticated structures and mechanisms in the plant kingdom.
Internal water pressure is less than it is outside so water can pass through. The action of just flattening or curving the trap walls catches minute creatures. This physiological process enables the sudden release of the trap door when prey touch the bristle lines on the outside of the doorway. A sudden inflow of water can suck in the prey for digestion.
Researchers have found that such a door can close within a split second! Within 15 to 30 minutes after the meal, the trap is reset by passing internal water out to await the next victim.
UTRICULARIA SANDERSONII: This is a terrestrial variety of bladderwort.
Aquatic bladderworts live in wet ground or in the water. The main part of bladderwort plants always lie beneath the surface of the substrate. Among all flowering plants, bladderworts have a unique structure – no true roots but filaments called rhizoids with microscopic bladders on the stolons (extended rhizoids). As they are actually rootless, they do not survive by absorbing nutrients from the medium.
Bladderworts can form dense leaf carpet mosses that bear minute complex and spurred flowers. The flowers are as stunning as orchids, and the petals come in shades of yellow, pink, purple, blue and white. Some even have a highly contrasting coloured throat. They have long stalks that emerge several inches above the water level and can seem clear to the naked eye.
Utricularia macrorhiza is a fairly big underwater bladderwort. It can reach up to eight inches in height with yellow flowers that are almost one inch in size.
At the Putrajaya Botanical Gardens, we can find several species with small red flower stalks and white petals including the Melaka bladderwort (Utricularia minutissima). A total of 14 species have been recorded in Peninsular Malaysia, which can be found naturally in different habitats.
Key points to remember
The terrestrial species require acidic and waterlogged soils as well as adequate sun to thrive but aquatic species need open ponds with ogliotrophic water. They will flower and bear fruits.
Bladderworts are sensitive to pollutants and environmental changes due to chemicals and organic matter. They are affected by fertiliser run-off and urbanisation.
There is no need to add any fertiliser as the plants have the means to trap prey for food.
Cultivation tips
These plants are sun lovers. Sunny outdoor spots or where there is direct sunlight are suitable.
Water with no mineral content is best, so if you are using tap water, ensure that it does not have a lot of minerals. Try reverse osmosis bottled water.
For terrestrial types of bladderwort, the medium can be a mixture of peat and sand or perlite (light cork-like particles). Shredded sphagnum moss mixed with perlite is also good.
Flooding of the medium is needed so top up the water level regularly. These plants will float on their own in the water.
To provide food or live prey for nutrients, you can add water fleas, microorganisms such as daphnia or brine shrimp larvae or crustaceans, which are used for feeding prawns and crabs.
Bladderworts are indeed an interesting addition to your collection of plants. Perhaps you can consider growing some soon.
Happy gardening. For details do send me an email.