Family: Bladderwort [Lentibulariaceae]



Both these genera of plants are  Carnivorous, obtaining either some or most of their nutrients from insects and other creatures.

Butterworts grow in damp places (not in lakes like the Bladderworts which grow in the UK) and they do have green basal leaves (which can photosynthesize) and roots which go into the soil, so are not totally dependent on insects for nutrition.

There are two types of glands on the leaves. Those on raised stalks are secretory cells and exude a sticky mucilage which encases the insect in its struggles. Thus incapacitated the insect releases nitrogenous compounds which initiate the release of several enzymes by glandular pores in the leaf surface. The enzymes, Acid Phosphatase, Esterase, Ribonuclease, Protease and Amylase, digest the insect into a soup that is absorbed by the same pores in the leaf surface, leaving just the exo-skeleton of the insect on the surface. The enzymes are also re-absorbed by the pores on the leaf surface. Job well done, ready for the next insect to perchance upon the leaf surface.

Bladderworts, on the other hand, are aquatic, either free-floating or anchored in fresh water (all species have these two forms).

Bladderworts are so called because they have tiny flask-shaped bladders along their underwater stems (which are numerous, compoundly branched and fern-like). Although they do have chlorophyll in the filigree fern-like green leaves below the surface of the water with which they can synthesize their own products. They obtain obtain other nutrients by the dissolution of insects and water-creatures and their subsequent absorption. Bladderworts are so called because they have tiny flask-shaped bladders along their underwater stems (which are numerous, compoundly branched and fern-like).

When a tiny insect or other creature (such as zooplankton) touches the very sensitive hairs near the opening of the trapdoor on the underwater bladder (which is under negative pressure - i.e. a partial vacuum) it abruptly opens in 200µs and the insect is sucked in at speed with the entering water. The trapdoor then quickly shuts again within 15ms trapping the insect within. The insect is slowly dissolved by enzymes or bacteria whereupon the released nutrients are absorbed by the plant. This presumably consists of a lot of nitrogenous compounds which it may not be able to obtain in sufficient quantities from the water. The speed with which the trapdoor opens and then shuts beggars belief - it outpaces the closing of the traps in Venus Flytrap! It happens faster than the blink of the eye uTube video of Bladderwort trap capturing underwater creature. In as few as 15 minutes the prey is dissolved and the trapdoor then resets itself by closing and pumping the water partially out of it ready to suck in the next victim (or 'sucker') when the hair-trigger is set off (or'pulled').

The bladders of bladderworts vary in size depending upon species, the smallest are just 0.2mm whilst the largest are some 1000 times larger at 1.2cm. Their size will have an impact on how fast each can operate; the smallest acting much faster than the largest. Unlike the triggers in Venus Flytraps, which are chemically driven, the trapdoor on the bladders of Bladderworts are driven entirely mechanically sprung lever triggers (in a similar vein to the trigger on a mousetrap). The trap itself consumes a lot of energy to set and establish the negative pressure within and is driven by a 2-step ion-pumping process repeatedly involving ATP and two cysteine molecules amongst other helpers and providers.

Worldwide there are thought to be 214 species of Bladderwort; less than half a dozen in the UK.

[PINGUICULA] Butterworts

Common Butterwort (Pinguicula vulgaris) Photo: © RWD

Great Butterwort (Pinguicula grandiflora) Photo: © Phil And Ann Farrer

[UTRICULARIA] Bladderworts

Lesser Bladderwort (Utricularia minor) Photo: © Dawn Nelson

Family: Bladderwort [Lentibulariaceae]

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