BINDWEED TRIBE 



195 



Natural Order LIII 



POLEMONIACEiE. Jacob's Ladder Tribe 



Calyx deeply 5-cleft, not falling off ; corolla 

 regular, 5-lobed ; stamens 5, from the middle 

 of the tube of the corolla ; ovary 3-celled ; 

 style single ; stigma 3-cleft ; capsule 3-celled, 

 3-valved. Herbaceous plants, often with showy 

 flowers, which are remarkable for the blue 

 colour of their pollen. They are most com- 

 mon in the temperate parts of America, but 

 within the tropics are unknown. None of the 

 species possess remarkable properties, but 

 several are favourite garden flowers, as Phlox, 

 Gilia, Polemonium, and Coboea. 



1. Polemonium (Jacob's Ladder). Corolla 

 wheel-shaped, with erect lobes; stamens bearded 

 at the base ; cells of the capsule many-seeded. 

 (Name, the Greek name of the plant.) 



Polemonium 



CtERULEUM 



{Blue Jacob's Ladder) 



I. Polemonium (Greek Valerian) 



1. P. cozruleum (Greek Valerian, Blue Jacob's Ladder). The only 

 British species. A tall, erect plant 1-2 feet high, with an angular 

 stem ; pinnate, smooth leaves ; and numerous terminal large blue 

 or white flowers. Occasionally found in woods in the north, but 

 very rare ; a common garden flower, not easily rooted out when it 

 has once established itself. Fl. June, July. Perennial. 



Natural Order LIV 

 CONVOLVULACE.E. The Bindweed Tribe 



Calyx in five divisions, imbricated, often very unequal, not falling 

 off ; corolla of 1 petal, regular, plaited when in bud ; stamens 5, 

 from the base of the corolla ; ovary 2 to 4-celled, few-seeded, sur- 

 rounded below by a fleshy ring ; style 1 ; stigmas 2 ; capsule 1 to 

 4-celled. An extensive and highly valuable tribe of plants, most 

 of which are herbaceous climbers, with large and very beautiful 

 flowers. They are most abundant within the tropics, where they 

 are among the most ornamental of climbing plants. As medicines, 

 also, they occupy an important station. The roots of Convolvulus 

 Scammonia, a Syrian species, furnishes scammony ; jalap is pre- 

 pared from a resin which abounds in the roots of several kinds of 

 Exogonium, a beautiful climber, with long crimson flowers ; and 



