328 SYSTEMATIC BOTANY. 



numerous exotic allies a long list will be found in all horticultural col- 

 lections. A large number of showy-flowered native weeds belong to this 

 Order, such as the Toad-flax (Linaria vulgaris) and several other species 

 of Linaria, the Speedwells (Veronica), the Red Rattle (Pedicularu) and 

 the Yellow Rattle (Rhinanthus) (so called from the ripe seeds rattling in 

 the dried inflated membranous capsules), the Foxglove, Mulleins ( Ver- 

 bascum), &c. 



LENTIBULARIACE^E (BUTTEB-WORTS) are small herbs growing 

 in water or wet places ; flowers with a 2-lipped calyx and a 2-lipped 

 personate spurred corolla ; stamens 2, with (confluent) 1-celled anthers ; 

 ovary 1-celled, with a free central placenta bearing several anatropous 

 seeds, with a thick straight embryo and no perisperm ; stigma bilabiate. 

 Illustrative Genera : Utricularia, L. ; Pinguicula, Tournef. 



Affinities, &c. This Order is interesting both from the habit and appear- 

 ance of the plants and from its affinities : on the one hand with the irre- 

 gular, didynamous gamopetalous 



Orders, through Scrophulariaceae, Fig. 426. Fig. 427. 



with which it agrees in the calyx, 

 corolla, and stamens, and on the other 

 hand with the regular Sympetalse, 

 through Primulacese, with which it 

 is connected by the free central pla- 

 centa. Dickson says the thalamus 

 in development begins to show irre- 

 gular growth before there is any Fi g . 425. Flower of Utricularia. 



appearance of the parts of the flower, Fig. 427. Air-sac of the leaf of Utricularia. 



and that the pistil is 5-carpous ; the 



embryo is sometimes mono- ID other species dicotyledonous. The 

 structure of the leaves of the Utricularice, especially that of their pouches 

 or air-floats (fig. 427), is very curious. Pringsheim considers these 

 pouches to be dilatations of a branch. The plants are found in all parts 

 of the globe ; the Utricularia are aquatic, one curious Brazilian species 

 ( U. nelumbifolia] growing in the water retained in the axils of the sheath- 

 ing leaves of a Tillandsia. In Utricularia the radicle aborts and the adult 

 plant is rootless ; the submerged capillary branches have often been mis- 

 taken for leaves or roots. The pitchers of Utricularia and the leaves of 

 Pinguicula have alike the property of dissolving and absorbing animal 

 matter, such as insects, &c. PingmculfZ are bog-plants ; and P. vulgaris 

 is said to have the property of coagulating milk. 



Division III. Apetalae or Incomplete. 



Dicotyledonous plants with a green or coloured calyx and no 

 petals, or with a calyx-like perianth of more than one whorl, or 

 with the floral envelopes reduced to one or more bract-like pieces, 

 or altogether absent. Flowers often unisexual. 



Exceptions, &c. The above characters are more or less artificial, and 



