•220 



Affinities. The ternary division of the ovarium connected with the 

 pentandrous corolla and 5-lobed calyx bring this order near Convolvulaceap, 

 from which the' habit, embryo, and corolla, distinguish it ; from Gentianese, 

 to which it also approaches, the 3-celled ovarium divides it. It is remark- 

 able for the blue colour of the pollen, which is usually of that hue, 

 whatever may be the colour of the corolla. In Collomia linearis I have 

 noticed (in Botanical Register, folio 1166) that the dilatution of the rau- 

 cous matter in which the seeds are enveloped, and which, when they are 

 thrown into water forms around them like a cloud, depends upon the pre- 

 sence of an infinite multitude of exceedingly delicate and minute spiral 

 vessels, lying coiled up, spire within. spire, on the outside of the testa; when 

 dry, these vessels are confined upon the surface of the seed by its mucus, 

 without being able to manifest themselves ; but the instant water is applied," 

 the mucus dissolves and ceases to counteract the elasticity of the spiral ves- 

 sels, which then dart forward at right angles with the testa, each carrying 

 with it a sheath of mucus, in which it for a long time remains enveloped as 

 if in a membranous case. I know of no parallel to this, except in Casuarina, 

 in which the whole of the inside of the testa consists of minute spiral 

 vessels. 



Geography. Very abundant in both North and South America, in 

 temperate latitudes, particularly on the north-west side. It is stated by 

 Dr. Richardson, that the most northern limit in North America is 54°. Ediii. 

 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 Cobseacete from this order; but the only 

 differences 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 Cobseaceae, 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 pericarpiuin. Seeds flat, 

 winged, imbricated in a double row ; their integument mucilaginous ; albumen 

 fleshy ; embryo straight ; cotyledons leafy ; radicle (according to Don) infe- 

 rior. — Climbing shrubs. Leaves alternate, pinnated, their petiole length- 

 ened into a tendril. Flowers axillary, solitary. 



CCf. IIYDROLEACE^. 



R. Brown Prodr. 482. (1810) without a name ; Id. in Congo {181R) HYDROi.EACEiK, 



Kunth in Ilumb. N. G. et Sp. X 125. (1818); Syiiops. 2. 2M. (1823) Diapen- 



siACEiT., Link Hamlb. 1. 595. (182!)), a § o/ Convolvulaceae. 



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

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

 Anomalies. 



Essential Chauactku — Caly.v 5-parted, inferior, persistent, with iniliricated a-sti- 

 vation. Corolla liypogyiioiis, inonopetaloiiH, rej^nlar, not alwavs agreeing willi the calyx in 



