PHANEROGAMIA 



577 



andrcecia of the Personatae and Labiatiflorae, The varying number of 

 carpels, their not infrequent separation, and the variability in the 

 number, position, and structure of other parts of the flowers, while 

 establishing the connection of the Tubiflorae with other orders, confirm 

 the supposition of their 

 greater age. In the Person- 

 atae and Labiatiflorae, on the 

 other hand, the flowers appear 

 to be constructed in accord- 

 ance with a fixed type. 



Family Convolvulaeeae. 



— Corolla FOLDED LONGI- 

 TUDINALLY in the bud, 

 twisted, usually to the right ; 

 ovary bilocular, with two 

 erect ovules in each loculus ; 

 loculi often two-chambered ; 

 embryo curved. Mostly 

 climbing herbs and shrubs, 

 usually with latex (Fig. 

 561). 



The majority of the plants 

 in the family are sinistrorse 

 herbaceous climbers, with 

 heart-shaped leaves and con- "* 5^=-^ v 4 ^ 



SpicUOUS flowers, Usually with Fig. 561.— Convolvulus amnsis. 1, Part of a stem with 

 a funnel-shaped, Slightly lobed flowers; 2 a flower cut through longitudinally; 3> 



corolla. The fruit is a capsule fruit ; *■ seed : 5 ' floral diasram - (After Woss ™°-> 

 or berry. In addition to the normally assimilating leafy species, the 

 family of the Convolvulaeeae includes (species of the genus Cuscuta) 

 a number of thread-like parasitic plants almost devoid of chlorophyll. 

 The species of this genus twine about other plants and obtain nourish- 

 ment by sending out haustoria into their stems (cf. p. 208, Fig. 185). 



Representative Genera. — Convolvulus, with two-cleft style {e.g. C. arvensis 

 Bindweed, Fig. 561) ; Oalystegia (Bracted Bindweed), like the preceding, but with 

 two large bracteoles ; Ipomoea, style four-cleft (e.g. I. purpurea, the common Morning 

 Glory) ; Cuscuta (Dodder). 



Geographical Distribution. — The Convolvulaeeae are most extensively 

 represented in tropical America. Several species of this family are well-known 

 ornamental plants. Ipomoea Batatas is largely cultivated for the tuberous roots 

 (Sweet Potatoes). 



Officinal. — Ipomoea Purga, a Mexican climbing plant, yielding Jalap, 



TUBERA JALAPAE. 



The Polemoniaeeae differ from the Convolvulaeeae in having three carpels and 

 no latex. Various species of Polemonium, Cobaea and Phlox are ornamental 

 plants. 



Family Boraginaeeae. — Corolla with imbricate aestivation : ovary 



2 Y 



