THE DICOTYLEDONES 



1899 



Gorse and other plants are among the more common. 'I'he plants are 

 climbers with pink, yellow or white filamentous stems. The seed on 

 germination produces a thin leafless stem which grows upright and then 

 curves and rotates to encounter a host (Fig. 1817). If it fails to make 

 contact it collapses to the ground and remains quiescent for several weeks 



Fig. 1817. — CitscKta. Stages in the germination and development 

 of the seedhng. (After Kenier and Oliver.) 



only to renew its activity again later. If it again fails to find a host, the 

 seedling dies. After attachment to a suitable host by haustoria has been 

 established the parasite loses its connection with the soil. We shall consider 

 the structure in greater detail in Volume IV. 



Solanaceae 



The members of this family are mostly herbaceous plants, many of 

 which are annual, some are climbers and a few are woody. The leaves 

 are alternate, simple or compound. Stipules are absent. Adnation of leaves 

 or ot bracts to their axillary shoots is common in the family and results in 

 complex changes in the plant form. 



The family includes a number of common or well-known plants, many 

 of which are found wild in Britain. Among the common British species 

 we may mention Solatium dulcamara (Bitter Sweet), S. nigrum (Woody 

 Nightshade), Atropa belladonna (Deadly Nightshade) and Hyoscyamus 

 niger (Henbane). Other species commonly grown in Britain are: Datura 

 stramonium (Thorn Apple), Solanum tuberosum (Potato), Nicotiaua tabacum 

 (Tobacco), Lycium halamifolium (Tea plant) (not to be confused with 

 Camellia sinensis, the Tea Bush from which the beverage is obtained), 

 Mandragora officinalis (Mandrake) and Physalis alkekengi (Winter Cherry). 

 In addition there are a number of other economic species which in this 

 country must usually be grown under glass. Of these we may mention 

 Solanum lycopersicum (Tomato), S. melongena (Aubergine or Egg Plant), 

 Capsicum spp. (Chillies) and Physalis peruviana (Cape Gooseberry'). 



