Utricularia L.
Annual or perennial, aquatic, terrestrial or epiphytic herbs. Roots 0, but root-like structures present. Stems modified to form rhizoids, stolons and leafy shoots. Lvs usually small, entire when terrestrial or emergent, capillary and much-divided when submerged, all with small bladder-like traps. Infl. racemose, emergent in aquatic spp., usually with a simple scape or peduncle. Fls 1-several. Calyx 2-lipped, divided almost to base, usually accrescent. Corolla yellow, white or purple; upper lip entire or lobed, mainly small; lower lip entire or 2-5-lobed, generally larger than upper lip, with palate or pouch present at base, ± raised and often gibbous; spur usually subulate or conic. Filaments usually curved, often dilated and flattened; anthers convergent. Stigma unequally lobed. Ovules 1-numerous. Capsule globose or ovoid, dehiscing in various ways. Seed very variable in shape and sculpturing.
Key
c. 180 spp., mostly tropical, but extending to N. and S. temperate zones. Native spp. 4, naturalised 1.
The structure of the active traps is very complex. Allan (1961) described 9 indigenous spp. for N.Z., but several were known only from 1 or 2 imperfect specimens and cannot be maintained as representing distinct spp. (P. Taylor, pers. comm.)
