Utricularia gibba L.

Small to medium sized, annual or perennial, affixed or suspended aquatic. Rhizoids absent or present, filiform, a few cm long, 0.2-0.4 mm thick, bearing a few very short, dichotomously divided branches with curved, papillose, apically obtuse segments; sometimes the rhizoids with an indefinite apical transformation as a stolon. Stolons usually numerous, much branched and often mat-forming, filiform, terete, glabrous, up to 20 cm long or longer, 0.2-1 mm thick, sometimes somewhat thicker and spongy. Leaves numerous, 0.5-1.5 cm long, ± uniform, the primary segments 2 (or sometimes reduced to 1), sparsely dichotomously branched into up to 8 (but usually not more than 4) ultimate segments, or sometimes 1 branch of each dichotomy replaced by a trap, the ultimate segments capillary, slightly flattened, laterally entire or sparsely denticulate, the apex of the segments and of the lateral teeth when present setulose. Traps rather few, lateral on the primary to penultimate segments, ovoid, stalked, 1-2.5 mm long, the mouth lateral with 2 dorsal, setiform, branched appendages and further dorsal, lateral and ventral setae, the internal glands 2-and 4-armed, the arms narrowly ovoid, with apex acute, 10-40 µ long, 1.5-6 times as long as wide, the quadrifids with both pairs ± equally slightly divergent. Inflorescence erect, emergent, (or sometimes submersed, much reduced and with cleistogamous flowers), 1-20(-30) cm long, solitary or frequently 2 or more arising together or in succession; peduncle filiform, terete, glabrous, ± straight, 0.4-0.8 mm thick. Scales usually 1, sometimes 2, at or near the middle of the peduncle, similar to the bract, or frequently absent. Bracts basifixed, semi-amplexicaul, approximately semicircular, with apex rounded, truncate or obscurely dentate, c. 1 mm long, minutely glandular, obscurely nerved. Bracteoles absent. Flowers (1-)2-6(-12), the raceme axis short to elongate; pedicels erect or spreading, filiform, terete, 0.2-3 cm long. Calyx lobes subequal, broadly ovate or circular with apex rounded, 1-3 mm long. Corolla yellow, often with reddish-brown nerves, 4-25 mm long; upper lip broadly ovate to almost circular, usually ± obscurely to distinctly 3-lobed; lower lip limb usually slightly smaller, circular to transversely elliptic, the base with a prominent, rounded, bilobed swelling, the apex rounded, entire; palate densely pubescent with simple unicellular hairs; spur narrowly conical or narrowly cylindrical from a conical base with apex obtuse or ± obscurely bifid, a little shorter than to distinctly longer than the lower lip, the distal part externally, sparsely, minutely stipitate-glandular. Filaments curved, 1-1.5 mm long, the anther thecae ± confluent. Ovary globose; style distinct; stigma lower lip transversely elliptic, the upper lip obsolete. Capsule globose, 2-3 mm in diameter, the wall membranous, tardily laterally bivalvate. Seeds imbricate on the placenta, thickly lenticular, approximately circular in dorsal view, 0.8-1 mm in diameter, with a relatively broad, thick wing, the wing produced to form a rounded lobe on that part of the margin which, in situ on the placenta, is nearest the apex of the capsule, the rest of the margin shallowly and irregularly dentate, the ventral surface smooth or sometimes with multicellular, obtusely conical processes, the testa cells small, slightly elongate, with the anticlinal boundaries sunken, the periclinal walls smooth, convex, but with the central area collapsing and becoming concave. Flowering more or less throughout the year when conditions are suitable.