1. Utricularia L. Bladderwort 



Perennial herbs, strictly aquatic, amphibious or in wet soil; stems slender; 

 leaves capillary-dissected and usually bearing bladderlike traps with a few 

 flagellae at their orifice and a valvelike action for trapping micro-organisms; 

 flowers 1 to several on slender scapes; calyx bilobed; corolla bilabiate, the lower 

 lip usually 3-lobed and with a conspicuous projecting usually bearded palate that 

 often closes the throat, the erect upper lip usually entire, spurred at the base 

 in front; stamens 2, the anthers convergent; capsule 2-valved. 



About 120 species that are cosmopolitan in distribution. 



Species of Utricularia are not only known to provide food but they also 

 provide shelter for fish and a habitat for minute animal life upon which fish feed. 

 These plants are incidentally eaten by wildfowl and muskrats. Some species 

 can become so concentrated in water bodies that, along with Myriophyllum spp., 

 Ceratophyllum demersum and Cabomba caroliniana, they become a nuisance and 

 hindrance to small boat navigation. With the lowering of water levels some of these 

 plants may die and foul the water with their decayed vegetation, contributing to 

 eutrophication. 



1. Leaves minute and linear or none, always inconspicuous; vegetative branches 

 subterranean or horizontal and submersed, only the erect filiform 

 flowering scape aerial; bladders minute or none (2) 



1. Leaves once to several times finely dichotomously branched, usually con- 



spicuous on the submersed stems, the flowers arising above the 

 surface of the water (4) 



2(1). Bracts at base of pedicels peltate, not accompanied by bractlets; pedicels 

 filiform, several times longer than the bracts 1. U. subulata. 



2. Bracts at base of pedicels basally attached, accompanied each by a pair of 



minute bractlets; pedicels stout, at most scarcely exceeding the 

 bracts (3) 



3(2). Flowers approximate, the expanding lower ones overtopping the unex- 

 panded buds above; pedicels mostly exserted beyond the basal 

 bracts; corolla (from tip of spur to tip of upper lobe) 15 mm. high 

 or more 2. U. cornuta. 



3. Flowers not crowded, the expanding lower ones not reaching unexpanded buds 



above; pedicels exceeded by the basal bracts; corolla 15 mm. high 

 or less 3. l). juncea. 



4(1). Leaves (at least the upper ones) in whorls of 4 to 9, the petioles often 

 inflated (5) 



4. Leaves all alternate, the petioles never inflated (7) 



5(4). Flowers rose-purple; petioles not inflated 4. U. purpurea. 



5. Flowers yellow; scape provided about or below the middle with a whorl of 



inflated petioles that act as floats (6) 



6(5). Flowers usually 9 to 14; pedicels recurved in fruit; corolla spur notched 

 at tip; raceme bracts longer than broad, never lobed; each lateral 

 foliar unit with its primary basal division comprised of 2 unequal 

 forks; base of floats tapering gradually from the expanded central 

 portion toward the scape axis, terete in cross section, the tips much- 

 curved ventrally and submersed 5. U. inflata. 



6. Flowers usually 3 or 4; pedicels rarely recurved in fruit, mostly stiffly erect- 



ascending; corolla spur never notched at tip, rounded or with a 

 small terminal papilla; raceme bracts as broad as long or broader, 

 variable with respect to lobing; each lateral foliar unit with primary 

 basal division comprised of 2 equal forks; bases of floats uniform in 

 breadth, tapering abruptly only at the scape axis, flattened in cross 



section, their tips scarcely curved ventrally, usually straight 



6. U. radiata. 



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