Bladderwort is a submerged or free-floating, mat-forming carnivorous aquatic plant. It has no root system. Adapted to low-nutrient wetlands, it is found in lakes, on lake edges, and muddy disturbed sites in the lowlands. Bladderwort is classified as a potential specialist invasive species that can outcompete native bladderworts in lowland wetland ecosystems. It is now found in all continents except Antarctica.
I. Appearance and Characteristics
Utricularia gibba, commonly known as the humped bladderwort or floating bladderwort, is a small, mat-forming species of carnivorous aquatic bladderwort. I
Utricularia gibba is an aquatic carnivorous plant that belongs to the genus Utricularia, or bladderworts. The specific epithet gibba is Latin for “hump” or “swelling” – a reference to the inflated base of the lower lip of the corolla. It is a small- to medium-sized aquatic plant that can either be affixed to the substrate in shallow water or free-floating in the water column, however it will likely flower more if supported by a substrate beneath shallow water. It forms mats of criss-crossing, branching, thread-like stolons, each growing to approximately 20 cm (8 in) or longer and 0.2–1 mm thick.
What are sometime described as leaves or leaf-like organs – the actual distinction is difficult in the reduced morphology – are numerous and scattered along the length of the stolons and are 0.5–1.5 cm (0.2–0.6 in) long with a very short dichotomous branching pattern toward the tip of anywhere from one to eight branches but usually not more than four. The bladder traps take the place of some of these distal branches on the leaf-like structures.
The traps are ovoid and are attached to the leaf-like structure by a short stalk; each trap is 1–2.5 mm long and has two primary setiform branched appendages on top and some smaller appendages surrounding the entrance to the trap. The appendages are the trigger that sets the trap off and vacuums the prey that touched it into the bladder to be digested.
Inflorescences are erect and typically emerge from the water to about 20 cm (8 in) tall, though in some cases they can be submerged and produce cleistogamous flowers. Inflorescences can produce anywhere from one to twelve flowers but it is unusual to see anything other than two to six flowers per inflorescence. Individual flowers are yellow, often with reddish-brown nerves, and are split into two lips: the upper lip is almost circular and weakly separated into three lobes while the lower lip is slightly smaller, also circular, and has a rounded, bilobed swelling in the center.
The spur is narrowly conical or cylindrical and curves down below the flower, varying in length from being just shorter than to noticeably longer than the lower lip. Utricularia gibba will flower throughout the year whenever conditions are favorable. Flowers, specifically the corolla, vary in size across this species’ large distribution from 0.8 to 1.5 cm (0.3 to 0.6 in).
The diploid chromosome number for U. gibba is 2n = 28.
Utricularia gibba has a vast geographic range and is native to the eastern United States, southeastern Canada, Central America, the Caribbean, the western Mediterranean, Southern Africa and southern India. It is considered an invasive species in Hawai’i, Australia, Japan, Brazil, New Zealand, Singapore, Serbia, Hungary and the United Kingdom.
It grows in ponds and lakes or shallow water in ditches, pools, bogs, swamps, and marshes that may be still or slowly flowing. It can sometimes be found growing in deep water but will not flower unless the inflorescences are supported near the surface by living or dead vegetation. The waters in which it grows are typically poor in available phosphorus and nitrogen.
II. How to Grow and Care
Bladderwort is an aquatic carnivorous plant that flourishes in nutrient-poor, acidic waters. It requires minimal maintenance, with an emphasis on ensuring consistent water quality and sunlight exposure. Special care points include maintaining a water pH of around 6 and providing ample light for proper growth. Its straightforward care requirements position it as an accessible choice for enthusiasts.
Sunlight
Bladderwort thrives best under full sun conditions, which entails exposure to unfiltered or direct sunlight for at least 6 hours a day. This level of light intensity is essential for optimal growth and flowering, as it drives photosynthesis, aiding bladderwort’s unique carnivorous feeding habits. Bladderwort’s tolerance to light variations allows it to also grow in partial sun, where it receives some shade during the day. However, lower light levels may result in less vigorous growth and reduced bloom production.
Adaptively, bladderwort can modulate leaf orientation and arrangement to maximize light capture. When grown outdoors, bladderwort should be positioned in areas that offer generous lighting, preferably without obstruction from taller flora.
Watering
Originating from aquatic and marshy environments, bladderwort has adapted to thrive in consistently moist conditions, reflecting its natural preference for wet habitats. Its water habits include a high tolerance for saturated soils but require a balance to prevent root rot. Watering should occur once every week to maintain the desired moisture level.
As an aquatic carnivorous plant, bladderwort is often found submerged or floating, indicating it’s typically grown outdoors where it can form mats on the surface of calm waters. This growth habit is closely tied to its need for abundant water, which supports both its foliage and unique feeding mechanism.
Propagation
To propagate bladderwort, the division method is most effective. Begin by gently separating the rhizomes, ensuring each section has at least one growth point. Plant divisions in a well-draining, nutrient-rich substrate, maintaining consistent moisture without waterlogging. Adequate sunlight and warmth will encourage vigorous growth, while periodic feeding will support robust development. Handle this carnivorous aquatic species with care, avoiding damage to the delicate traps.
Transplanting
For bladderwort, the prime of spring brings the most success for transplanting, as it allows for robust growth. Choose a spot with ample moisture and gentle sunlight; patience and gentleness when relocating will ensure a thriving bladderwort.
Repotting
Bladderwort, an aquatic carnivorous plant, thrives in shallow water, lacking a root system. Repotting every 2-3 years, preferably during the growing season for rejuvenation. Choose a container that accommodates its free-floating nature, ensuring ample space for traps. Post-repot, ensure consistent water levels and nutrient-rich media to promote healthy regrowth. Though resilient, attention to water quality is crucial for optimal plant health.
III. Uses and Benefits
Utricularia gibba has the reputation of being one of the easier aquatic bladderworts to grow, often being described as a weed in cultivation. In his 1998 book The Savage Garden: Cultivating Carnivorous Plants, Peter D’Amato advised that successful cultivation could be achieved with U. gibba floating in a small cup or bowl, within waterlogged peat, or even among the water-filled trays of other plants. It can also easily be grown in aquaria.
