630 



CONVOLVULACEiE. 



[Perigynous Exogens. 



Order CCXLI. CONVOLVULACEiE.— Bindweeds. 



Convolviili, Jiiss. Gen. 133. (1789).— Convolvulaceae, R. Brown, Prodr. 481. (1810); Lindl. Si/nops. 

 167. (1829); Choist/ in Mem. Soc. Phys. Genev. (1834); Alph. DC. Prodr. 9. 323. 



Diagnosis. — Solanal Exogens, with 5 fi'ee stamensj hasal placentce, and leafy doubled up 



cotyledons. 



Herbaceous plants or slirubs, usually twining and milky, smooth, or with a simple 

 pubescence, sometimes erect bushes. Leaves alteraate, imdivided, or lobed, seldom 



Fig. CCCGXXIII, 



piuuatifid, with no stipules. Inflorescence axillary or terminal ; pedimcles 1- or many- 

 flowered, the partial ones generally >vith 2 bracts, which sometimes enlarge greatly 

 after flowering. In Mina the inflorescence is a one-sided and almost scorpioid raceme. 

 Calyx persistent, in 5 divisions, remarkably imbricated, as if in more whorls than 

 one, often very unequal. Corolla monopetalous, h}7)og}Tious, regular, deciduous ; the 

 limb 5-lobed, plaited ; the tube without scales. Stamens 5, inserted into the base of 

 the corolla, and alternate with its segments. Ovary simple, with 2 or 4 cells, seldom 

 mth 1 ; sometimes in 2 or 4 distinct divisions ; few-seeded ; the ovules definite and 

 erect, when more tlian 1 collateral ; style 1, usually divided at the top, or as many as 

 the di\isions of the ovary, and arising from theu' base ; stigmas obtuse or acute. Disk 

 annular, h^-pogjTious. Capsule with from 1 to 4 cells, succulent or capsular ; the valves 

 fitting, at their edges, to the angles of a loose dissepiment, bearing the seeds at its base. 

 Seeds with a small quantity of mucUaginous albumen ; embryo curved ; cotyledons 

 leafy, shrivelled ; radicle inferior, next the hUum. 



The plaited corolla, imbricated calyx, and climbing habit, are the primd facie 

 marks of tliis Order, which approaches Sebestens in its shrivelled cotyledons, and 

 through that tribe Borageworts. Mina here, with its almost scorpioid inflorescence, 

 and Nolanads among the Echials, would seem to estabhsh even a more du-ect 

 relationship between Bindweeds and that Order. Phloxworts are known by their 

 more copious albumen, straight embryo, and loculicidal dehiscence, which in Bind- 

 weeds is always opposite the dissepiments. Hydrophyls are characterised by their 

 parietal placentae, and taper embryo lying in the midst of fleshy albumen. Night- 

 shades have a dicarpellary finiit, with axile placentee, and numerous seeds ; otherwise, 

 they are sometimes vei'y like the shrubby erect species of Bindweed. The Order has 

 been re-arranged by Choisy in De CandoUe's Prodremus, but that author has been 

 sharply criticised by Bentham {London Journal of Botany, May, 1845, p. 244), and 

 with justice. 



Pig. CCCCXXllI.— Ipomoea Batatoides. 1. the pistil and annular disk; 2. a transverse section of 

 the ovary ; 3. a capsule of Convolvulus tricolor ; 4. a vertical section of the seed of that species. 



