704 BOTANY PART n 



A special group includes a number of closely related genera which have 

 adopted a more or less completely parasitic mode of life. The most completely 

 parasitic form is Lathraea ( 35 ), the species of which have no trace of chlorophyll ; 

 L. squamaria, the Tooth wort, is parasitic on the roots of the Hazel. Many (e.g. 

 Toszia, Bartsia, Euphrasia, Odontites, Pedicularis, Melampyrum, Alectorolophus) 

 are semiparasitic. Although they possess green leaves they attach themselves 

 by means of haustoria to the roots of other plants, from which they obtain 

 nutrient materials. 



OFFICIAL. Digitalis purpurea yields DIGITALIS FOLIA. Picorhiza kurroa. 



Family 3. Orobanchaceae. Root -parasites, without chlorophyll. Flower as 

 in the Scrophulariaceae, but with a unilocular ovary. Several British species of 

 Orobanche, parasitic on various host plants (Fig. 764). 



Family 4. Lentibulariaceae. Marsh- or water-plants. They capture and digest 

 insects. Utricularia ( 3G ), Pinguicula. 



Family 5. Plantaginaceae. Reduced forms. Litorella lacustris. Plantago. 

 Plantain ; anemophilous, and protogynous. 



OFFICIAL. Plantago ovata. 



2. Ovary Inferior 

 Order 7. Rubiinae 



This order is related to the Umbelliflorae, where also the ovary is 

 inferior. The flowers are tetramerous or pentamerous ; the numbers 

 of stamens and carpels vary in the zygomorphic and asymmetric 

 flowers. 



Family 1. Rubiaeeae ( 37 ). Herbs, shrubs, or trees, with simple 

 decussate leaves and stipules. Flowers actinomorphic. Ovary 

 bilocular. 



The few native Rubiaeeae all belong to the group represented by 

 Asperula (Woodruff), Galium, EuUa. These genera are characterised 

 by the resemblance of the stipules to the leaves ; usually a whorl of 

 six members is borne at each node, but sometimes it is reduced 

 to four by the union of the stipules in pairs ; the numbers may, 

 however, vary. 



In the tropics the Rubiaeeae are abundantly represented by trees, shrubs, 

 climbers, and epiphytes. One of the most important Rubiaeeae is Cinchona, a 

 genus from the S. American Andes, now cultivated in the mountains of nearly all 

 tropical colonies (Fig. 765). Stipules deciduous. Flowers in terminal panicles ; 

 corolla tubular, with an expanded terminal portion fringed at the margin. 

 Fruit, a capsule, with winged seeds (Fig. 766). Coffea, the Coffee plant, is a 

 shrub ; C. arabica (Fig. 767) and C. liberica are important economic plants, 

 originally derived from Africa, and now cultivated throughout the tropics. The 

 fruits are two-seeded drupes. The pericarp becomes differentiated into a succulent 

 exocarp and a thin stony endocarp, which encloses the two seeds with their thin 

 silvery seed-coats. These are the coffee-beans. The noteworthy tuberous epiphytic 

 plants Hydnophytum and Myrmecodia ( 37 ) have also succulent fruits ; according 

 to the most recent investigations they utilise the excreta of the ants which inhabit 

 the cavities in the stems. Species of Psychotria and Pavetta are also of physio- 



