I9IO 



A TEXTBOOK OF THEORETICAL BOTANY 



Fig. 1831. — Lathraea clandestine. Emergent inflorescences. 



The family contains a number of other genera most of which are 

 tropical and among these may be mentioned Christisonia in Asia on Bamboos 

 and Aeginetia, which occurs on Sugar Cane, in south-eastern Asia. 



The Lentibulariaceae are a small family containing five genera with 

 about 250 species, of which one genus, Utricidaria, contains over 200. One 

 other important genus, Pingiiiciila, contains about thirty species. Both these 

 genera are represented in the British Flora. Utricularia (Fig. 1832), the 

 Bladderwort, is represented in Britain by four species while there are also 

 four British species of Pinguicula (Fig. 1833), the Butterwort. Both genera 

 possess the carnivorous habit, though the mechanism of capture in each 

 genus is completely diflFerent. Utricularia is a submerged, rootless water 

 plant in which bladders are developed on the finely divided leaves. The 

 flowers rise above the water and are hermaphrodite and zygomorphic. 

 Calyx and corolla consist of five united parts. There are only two stamens 

 and the ovary consists of two carpels forming a single loculus in which 

 numerous ovules are borne on a free-central placenta. The fruit is a capsule 

 opening by valves. In the germination of the embryo it is impossible to 

 differentiate between stem and leaf, for it produces an irregular cell-mass 

 on which arises the leaf rudiments, and no primary root is formed. 



Pinguicula is a genus of perennial herbs characteristic of marshy ground 

 and bearing sparse roots. The leaves are large and form a rosette, from 

 which a one-flowered, axillary flower spike arises. The embryo generally 

 produces only one cotyledon. 



Utricularia is widely distributed in tropical and temperate regions, but 



