THE DICOTYLEDONES 1915 



perennial climber with orange flowers, which is frequently grown in gardens. 

 Tecoma radicans, the Trumpet Flower, is a favourite self-clinging climber on 

 house walls in warm climates. 



The Acanthaceae are a family of herbs or shrubs with about 2,000 

 species and 250 genera found in the w^armer parts of the world. Some are 

 seen in this country as hothouse plants, which are grown on account of their 

 large spikes of bright-coloured flowers often with large coloured bracts. 

 Others, as for example. Acanthus mollis (Fig. 1838), can be cultivated in the 

 open in the warmer parts of Great Britain. In some the attractive appear- 

 ance of the plant is enhanced by the coloured bracts (Fig. 1839). 



The Pedaliaceae are a small family of annual or perennial herbs which 

 includes only about sixty species divided among twenty genera. Thev 

 occur mainly in South Africa, Madagascar, Indo-Malaya and Australia. 

 Sesamiim indicum (Sesame) is widely cultivated for its oily seeds. Two 

 genera, Harpagophytiim and Martynia (Figs. 1840 and 1841), have already 

 been referred to (p. 1565) because of their elaborate barbed fruits. 



Fig. 1841. — Martynia. Longitudinal section of 

 flower. The two stigmatic lobes are normally 

 spreading but close up on being touched, thus 

 trapping pollen from visiting insects. 



Scrophulariaceae 



The members of the Scrophulariaceae are predominantly herbs, mostly 

 perennial, while trees and shrubs are rare. The flowers show a wide range 

 of structure which is reflected in the method of classification within the 

 family. The family is found in all climates but most abundantly in temperate 

 regions and very rarely either near the equator or towards the poles (Fig. 

 1842). Some members of the family are parasitic and others semi- 

 parasitic. 



There are many common genera in the British Flora, while many more 

 are commonly cultivated in gardens. Familiar British examples are 

 Digitalis (Foxglove), Veronica (Speedwell), Scrophularia (Fig Wort), 

 Linaria (Toadflax), Verbascum (Mullein). Among the semi-parasitic genera 

 found in Britain are Euphrasia (P>yebright), Pediciilaris (Lousewort), 

 Melampyrum (Cow-wheat), Rhinanthus (Yellow Rattle) and Bartsia. 



