A beautiful and innocent flower above the water surface, a killer underneath… thin and delicate as a hairy root Utricularia gibba is hidden awaiting its next victim…
Main stem carrying the globose traps of Utricularia gibba (scale in milimeters) by Ada Molina
As a string of beads, a set of bladder-like traps are neatly arranged along the stems. These traps, borne on short stalks attached to leaf-like structures, are provided with hair-like projections at the mouth that act as triggers. Once stimulated by a passing organism they will open inward the lid at the mouth, hoovering the prey and digesting it.
The humped bladderwort belongs to the Lentibulariaceae family. Found in ponds and lakes, either in shallow water or floating, from lowland to open montane microhabitats (Chew & Haron 2012), this carnivorous plant has become a fairly common widespread guest of aquatic habitats all over the world. Mainly distributed in pantropical regions, it can also be found in further south areas in South America, Africa and Australia, and also in Canada.
Different synonyms have been given to different types around the world such as: Utricularia bifidocalcar Good (Angola), U. exoleta R.Br (Australia), U. gibba subsp. exoleta (R Br) P. Taylor (Australia), U. kalmaloensis A. Chev. (U.S.A.) , U. obtusa Sw. (Jamaica), U. riccioides A. Chev. (Ivory Coast) and U. tricrenata Hiern. (Angola).
Leaves or “leaves”?… a fuzzy morphology
Also known as the creeping bladderwort, this species lacks the orthodox distinction of ‘root’, ‘stem’ and ‘leaf’ (Rutishauser & Isler 2001). This rootless annual or perennial plant forms a mat of branching, thread-like stems showing a ‘leaf-shoot indistinction’.
Many attempts have been made to describe its leaf morphology and arrangement. “Leaves usually 2-forked” was Mason’s (1957) leaf description contribution. On the contrary, in both Paiva et al. (1986) and Hickman’s (1993) keys to the genus no true leaves are described as such but refer to as green branch systems of ± linear or thread-like segments, alternate, with a 2-parted pattern. However, since evolution have blurred distinction, the result is organs with unique combinations of features, and an unsolved mystery.
Utricularia gibba L. a) plant structure; b) trap; c) section of the stem; d) bract; e, f, g, h) frontal, latera and back view of the flower; i) calyx and gynoecium; k, l) gynoecium; m) corolla; n) fruit; o) seed. Image from Flora Ibérica (Real Jardín Botánico, Madrid) under cc license
Gibba is Latin for “hump”, possibly referring to the bi-lobed swelling near the base of the flower lip (Chew 2009). The flowers, usually 2-6, are 4-25 mm long, yellow with brown or reddish nerves on the palate (swelling), which is densely hairy. The superior lip is circular obscurely 3-lobed; the inferior lip is usually shorter and narrower than the superior, circular as well, however usually entire and rarely emarginate. Typical of the genus is the presence of spurs. In this case, the spur is conical to narrowly cylindrical, the apex bearing a few shortly stalked glands (Kew 2002).
A bit fussy when it comes to flowering, our floating femme fatale will delight the pond community with its beautiful flowers only if hold near the surface by any kind of support such as vegetation or substrate. The flowers will be born on erect, solitary or often several inflorescences 2-35 cm high.
…maybe a useful carnivorous “weed”!
Although considered a weed in several countries, Utricularia gibba can have a beneficial environmental role in certain habitats. Along with other species of the genus, its sensitivity to water trophicity, biotic and chemical pollutions could serve as indicator to predict the general health and recovery of many wet microhabitat types (Chew & Haron 2012).
The utilization of the plant as a biological control agent of human parasitic diseases has been investigated since the 1970’s, however no specific roles can yet be ascribed.
Did you know that…?
Peter Taylor‘s culmination of 41 years of research was a taxonomic monograph on the genus Utricularia published in 1989. A marvelous 736 pages tome where each species is illustrated with a full-page line drawing created by the world’s authority on bladderworts.
You can read more about the species in Atlas of Living Australia.
References
CHEW M. Y. (2009). Utricularia gibba. Flora of Peninsular Malaysia Online -Newsletter Vol. 41/15.
CHEW M.Y. & HARON N.W. (2012). Medicinal and Environmental Indicator Species of Utricularia from Montane Forest of Peninsular Malaysia. ScientificWorldJournal 2012:234820.
HICKMAN J.C. (1993). The Jepson: Higher Plants of California. University of California Press, Berkeley. 1400 pp.
MASON H.L. (1957). A Flora of the Marshes of California. Univeristy of California, Berkeley and Los Angeles.
PAIVA F., SALES F., HEDGE I.C., AEDO C., ALDASORO J.J., CASTROJO S., HERRERO & VELAYOS, M. (1986). Flora Ibérica: plantas vasculares de la Península Ibérica e Islas Baleares. XIV Myoporaceae-Campanulaceae. Real Jardín Botánico, Madrid.
KEW, ROYAL BOTANIC GARDENS (2002). electronic Plant Information Centre. Published on the Internet; http://epic.kew.org/epic/
RUTISHAUSER R. & ISLER B. (2001). Developmental Genetics and Morphological Evolution of Flowering Plants, Especially Bladderworts (Utricularia): Fuzzy Arberian Morphology Complements Classical Morphology. Annals of Botany 88:1173-1202.
TAYLOR, P. (1989). The genus Utricularia – a taxonomic monograph. Kew Bulletin Additional Series XIV: London.