218 



ardson, that the most northern limit in North America is 54°, Edin. Phil. 

 Journ. 12. 209. In Europe and Asia they are much more uncommon. They 

 are unknown in tropical countries. 



Properties. None, or unknown. 



Examples. Polemonium, Collomia, Ipomopsis, Cantua, Gilia. 



N. B. Mr. Don distinguishes Cobaeaceae from this order ; but the only dif- 

 ferences of importance between the one and the other consist in the former 

 having a septicidal dehiscence and climbing habit ; characters, I fear, of too 

 little moment to be admitted as ordinal distinctions. The characters of Cobae- 

 aceae, as understood by Mr. Don, are these : 



Calyx leafy, 5-cleft, equal. Corolla inferior, campanulate, regular, 5-lobed, 

 with an imbricate aestivation. Stamens 5, equal, arising from the base of the 

 corolla ; anthers 2-celled, compressed. Ovarium superior, 3-celled, surrounded 

 with a fleshy secreting annular disk ; ovules several, ascending ; style simple \ 

 stigma trifid. Fruit capsular, 3-celled, 3-valved, with a septicidal dehiscence \ 

 placenta very large, 3-cornered, in the axis, its angles touching the line of 

 dehiscence of the pericarpium. Seeds flat, winged, imbricated in a double 

 row ; their integument mucilaginous ; albumen fleshy ; embryo straight ; 

 cotyledons leafy ; radicle (according to Don) inferior. — Climbing shrubs. 

 Leaves alternate, pinnated, their petiole lengthened into a tendril. Flower* 

 axillary, solitary. 



CCI. HYDROLEACE.E. 



/?. Broun Prodr. 482. (1810) without a name; Id. in Congo (1818). — Hydboleace.e, Kunth in 

 Humb. N. G. et Sp. 3. 125. (1818) ; Synops. 2. 234. (1823).— Diapensiace*, Link Handb. 

 1. 595. (1829), a%of Convolvulaceoe. 



Diagnosis. Monopetalous dicotyledons, with a superior 2- or 3-celled 

 ovarium, several styles, indefinite seeds, and a plaited or imbricated corolla. 

 Anomalies. 



Essential Character. — Calyx 5-parted, inferior, persistent, with imbricated aestivation. 

 Corolla hypogynous, monopetalous, regular, not always agreeing with the calyx in the num- 

 ber of its divisions. Stamens arising from the corolla, regular, agreeing in number with the 

 segments of the calyx ; anthers deeply lobed at the base. Ovarium superior, surrounded by 

 an annular disk, 2- or 3-celled ; styles 2 or 3 - T stigmas thickened. Fruit capsular, enclosed 

 in the calyx, 2- rarely 3-cclled, splitting through the middle of the cells ; valves therefore 

 bearing the dissepiments in their middle ; placenta either single and fungous, or double and 

 thin. Seeds indefinite, very small ; albumen fleshy, in the axis of which lies a taper, straight 

 embryo. — Herbaceous plants or undcr-shrubs, sometimes spiny. Leaves alternate, entire, or 

 lobed, without stipulsa, often covered with glandular or stinging haira. Flowers numerous, 

 axillary and terminal. 



Affinities. Separated from Convolvulacea? by Mr. Brown, on account of 

 their indefinite seeds, and taper embryo with small flat cotyledons in the midst 

 of fleshy albumen. To me they appear equally related to Boragineae, with 

 some of which Wigandia agrees in habit. Also related to Hydrophylleae the 

 membranous plates lining the tube of the corolla of that order being, according 

 to Von Martius (JV. G. 2. 138), analogous to the dilated base of the filaments 

 of Hydroleacete. 



Geography. No particular geographical limits can be assigned to this 

 order. Diapensia is found in Lapland, Wigandia in the Caraccas, Hydrolea 

 in the West Indies, and Nama in both the East and West Indies. 



Properties. Unknown, except that a bitter principle exists in Hy- 

 drolea. 



Examples. Hydrolea, Nama, Sagonea, Wigandia, Diapensia. 



