Bladderwort: Encyclopedia II - Bladderwort - Physical description

Bladderwort - Physical description

The main part of a Bladderwort plant always lies below the surface of its substrate. Terrestrial species sometimes produce a few photosynthetic leaf-shoots which lie unobtrusively flat against the surface of their soil, but in all species only the flowering stems rise above and are prominent. This means that the terrestrial species are generally visible only while they are in flower, although aquatic species can be observed below the surfaces of ponds and streams.

Bladderwort - Plant structure

Most species form long, thin, sometimes branching stems or stolons beneath the surface of their substrate, whether that be pond water or dripping moss in the canopy of a tropical rainforest. To these stolons are attached both the bladder traps and photosynthetic leaf-shoots, and in terrestrial species the shoots are thrust upward through the soil into the air or along the surface.

The name Bladderwort refers to the bladder-like traps. The generic name Utricularia is similarly derived from the Latin utriculus, a word which has many related meanings but which most commonly means wine flask or leather bottle. The aquatic members of the genus have the largest and most obvious bladders, and these were initially thought to be flotation devices before their carnivorous nature was discovered.

Bladderwort - Flowers and reproduction

Flowers are the only part of the plant clear of the underlying soil or water. They are usually produced at the end of thin, often vertical stems. They can range in size from a few millimetres across to two inches or more, and have two asymmetric labiate (unequal, lip-like) petals, the lower usually significantly larger than the upper. They can be of any colour, or of many colours, and are similar in structure to the flowers of a related carnivorous genus, Pinguicula.

The flowers of aquatic varieties like U. vulgaris are often described as similar to small yellow snapdragons, and the Australian species U. dichotoma can produce the effect of a field full of violets on nodding stems. The epiphytic species of South America, however, are generally considered to have the showiest, as well as the largest, flowers. It is these species that are frequently compared with orchids.

Certain plants in particular seasons might produce closed, self-pollinating (cleistogamous) flowers; but the same plant or species might produce open, insect-pollinated flowers elsewhere or at a different time of year, and with no obvious pattern. Sometimes, individual plants have both types of flower at the same time: aquatic species such as U. dimorphantha and U. geminiscapa, for example, usually have open flowers riding clear of the water and one or more closed, self-pollinating flowers beneath the water (1). Seeds are numerous and small, sometimes as small as 0.2 mm.

Adapted from the Wikipedia article "Physical description", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki