Gliick . — The Species of Utricularia of Great Britain. 609 
II. Morphology and Biology of Utricularia ochroleuca. 
As U. ochroleuca shows the nearest affinity to U. intermedia , it will be 
easily understood that in England U. ochroleuca and U. intermedia have 
been until now confused with one another. We must therefore, in the 
following treatment, also consider U. intermedia. 
Before entering into the specific differences between U. ochroleuca and 
U. intermedia , it is perhaps well to say a few words about the systematic 
grouping of the European species of Utricularia. It is appropriate here to 
distinguish the three following natural groups : 
(i) U. vulgaris. 
U. major (= neglect a). 
(U. exoleta.) 
(ii) U. intermedia. 
U. ochroleuca. 
(iii) U. minor. 
U. Bremii. 
U. vulgaris and major ( neglecta ) are the largest indigenous species. The 
leaves are bipartite and divided into numerous capillary terminal lobes, 
and bear many bladders. On the base of the flowering stem c rhizoids 5 
occur ; these are small metamorphosed shoots, which serve to anchor the 
flowering stems and to keep them in a vertical position, but are often 
rudimentary. 1 Besides, they produce ‘air-shoots’; these are metamor- 
phosed threadlike shoots, which grow upwards to the surface of the water, 
bearing small scales, and are of service for the exchange of gases. 2 
Utricularia ochroleuca and intermedia are much smaller plants than 
the two first mentioned. The shoots differentiate in two directions: 
one kind is covered with green, assimilating floating leaves ; the other is 
colourless and penetrates into the mud. The leaves of the green shoots 
may be divided into 7-15 terminal lobes, and may bear 0-3 bladders. 
The ‘ leaves ’ of the subterranean shoots are also colourless, and bear on 
fine filiform branches 3-8 bladders. ‘Rhizoids’ are also to be found on 
the base of the flowering stems, 3 but the ‘ air-shoots ’ are missing. 
U. minor and U. Bremii are the two smallest species, and indeed the 
latter exceeds the U. minor in its general habitat and in the size of its flowers. 
The shoots also differentiate into green assimilating and colourless under- 
ground shoots ; the green floating leaves may be divided into 14-20 
terminal lobes and may bear 7-8 bladders. ‘ Rhizoids ’ and also ‘ air-shoots ’ 
are missing on the flowering stem. 
1 Compare H. Gliick, Biologische und morphologische Untersuchungen liber Wasser- und 
Sumpfgewachse, vol. ii, pp. 66-72. 
2 Compare ibid., pp, 78-83. 
3 In respect of the ‘ rhizoids ’ see my above-mentioned work, vol. ii, p. 73. 
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