652 



BOTANY 



PART II 



Important Genera. — Convolvulus arvcnsis (Fig. 688), a perennial, twining, 

 herbaceous plant occurring everywhere by waysides, and as a weed iu corn-fields. 

 Flowers solitary, long-stalked, situated in the axils of the leaves and sometimes in 

 the axils of the bracteoles of another flower. Cahjstcgia has two large bracteoles 

 placed immediately beneath the calyx. C. sepiiim. The Dodder (Cu scuta) (^") is a 

 slender parasitic plant containing very little chlorophyll, which attaches itself by 

 means of haustoria to a number of ditlerent liost plants. The small flowers are 

 borne in dense clusters (of. p. 223, Fig. 196). Tpomoea is for the most part a 



Fk;. 691. — Erhiuiii cvhjare. Inflorescenop (l iiat. size). 

 Single flower and fruit, composed of tburnutlets (enlarged). 



Fig. <JW.—Bora(jo officinalis, a, 

 Flower ; b and e, fruit (nat. size). 



Fii:. 602.— Floral diafixams of (.1) Verbena officinalis (after 

 Bichler), and (D) Laminm (Labiatas). 



tropical genus ; several species are cultivated as ornamental plants. /. -pcscaprae 

 is one of the strand plants of tropical countries. 



Official. — Jalapa is obtained from Exogonium inirga (Fig. 689), a twining 

 plant, with tuberous lateral roots, occurring on the wooded, eastern slopes of the 

 Mexican^ tableland. Scammoniae radi.x is the dried root of Convolvulus 

 Scammoihia (Asia I\Iinor). 



Family 2. Polemoniaceae. — Carpels usually three. No milky juice. Polemonium 

 coeruleum occurs in Britain. Cobaea seamlens and Phlox are cultivated. 



Family .3. Hydrophyllaceae. — Phacelia tanacctifolia is often cultivated for the 

 sake of bees. Inflorcst-ence a eincinnus. 



Family 4. Boraginaceae. — Herljs, with alternate leaves. These and t\w. stems 



