Humped Bladderwort (Utricularia gibba)

Description

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) long 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 surrounded 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).