Common Name:
COMMON BLADDERWORT
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Coefficient of Conservatism:
6
Coefficient of Wetness:
-5
Wetness Index:
OBL
Physiognomy:
Nt P-Forb
B. Jones
Lakes of all kinds, interdunal (and other) ponds and swales, wet peatlands and marshes, rivers and streams. Often in water up to 2 m deep; the deepest recorded on Michigan specimens is 4.6 m.
Our plants are subsp. macrorhiza (J. Le Conte) R. T. Clausen (sometimes recognized as U. macrorhiza J. Le Conte) differing from European plants by small floral characters.
After the main forking of the leaves next to the stem, those of robust U. vulgaris often have a more pinnate than dichotomous aspect, with a slightly zigzag and broader central axis and many forked lateral segments. The main segments on such large leaves are sometimes flattish (at least when dried).
Fertile specimens are easily distinguished from other species, and so are those large coarse vegetative ones, with leaves 3–5 cm or more long and up to 22 levels of forking, bladders nearly or quite 5 mm long, and massive turions as much as 3 cm or more across. The total diameter of a leafy branch may be 10 cm. Small fragments of depauperate growth, on the other hand, are often not safely distinguishable from vegetative U. geminiscapa, although experience with good fertile material of both species will then help one decide on the basis of characters not able to be quantified to the extent desirable in a key. Utricularia geminiscapa is often said to have the ultimate segments of the leaves entire or with few spicules, while in U. vulgaris there are more numerous spicules. There is no consistent difference in number of spicules (always few), but in U. vulgaris they do tend to be somewhat larger, arising at times from a tiny green tooth on the leaf margin. In turions of U. vulgaris (usually 5–30 mm broad), the crowded leaves are heavily provided with glistening apical and marginal spicules often giving a grayish as well as minutely prickly aspect to the structure (like those of U. intermedia). The turions of U. geminiscapa run smaller, perhaps less compact, and certainly more green and less prickly in aspect. Utricularia geminiscapa is much more narrow in habitat and is never expected to develop a layer of marl on the foliage, whereas U. vulgaris when growing in alkaline water may develop (as do many other aquatics) a layer of carbonates.