233 
Gilia, Cav. 
Ipomopsis, Sm. 
Ipomeria, Isutt. 
Navarretia, R. et P. 
CEgochloa, Benth. 
Collomia, Nutt. 
Caldasia, Willd. 
Bonplandia, Cav. 
Hoitzia, Juss. 
Loeselia, L. 
Cantua, Juss. (33) 
Periphragmos, R. et P. 
? Cyananthus, Wall. (34) 
Heteryta, Raf. 
Don distinguishes Cobeeacese from this order ; but the only differences of 
importance between the one and the other appear to consist in the former 
having an unusually large lobed disk, a septicidal dehiscence and climbing 
habit ; distinctions, I fear, of too little moment to be admitted as of ordinal 
value. Tlie characters of Cobseacese, as understood by Don, are these : — 
Cob.s;ace:E, Don in Edinb. Phil. Journ. 10. 111. (1824) ; Link Handb. 1. 822. (1829). 
Essential Character. — 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. Ovary 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 inferior. — Climbing shrubs. alteiuate, 
pinnated, their petiole lengthened into a tendril. Flowers axillar>^, solitary. Don. 
Bartling (p. 186) remarks that the type of this order ought, in fact, to be 
referred to Bignoniacese ; hut all the arguments he adduces prove exactly the 
contrary. 
GENUS. 
Cobaea, Cav. 
Order CLXXVII * DIAPENSIACE^. 
Diapensiace^, Link Handb. 1. 595. (1829) ; a § o/ Convolvulaceae. 
Essential Character. — Calyx composed of 5 sepals which form a broken w'horl, are 
rather unequal, and much imbricated ; scarcely distinguishable from the bracts which are 
closely imbricated round it. Corolla monopetalous, regular, with an imbricated aestivation. 
Stamens 5, equal; the filaments petaloid and arising from the margin of the sinus of the 
corolla; anthers 2-celled, with a broad connective, bursting transversely ; in Pyxidanthera 
awned on the lower valve. Disk 0. Ovary superior, 3 -celled ; each placenta with 7 ovules 
in Pyxidanthera, with an indefinite number in Diapensia; style single, continuous with the 
ovar^' ; stigma sessile with 3 very short decurrent lobes. Capsule membranous or papery, 
surrounded with the permanent sepals, terminated by the rigid style or its base. Seeds 
with a brittle deeply pitted skin, peltate. Embryo filiform, with a long slender radicle and 
two very short cotyledons; lying across the hilum in a mass of fleshy albumen. — Prostrate 
undershrubs, with small densely imbricated leaves which have scarcely any visible veins. 
Motcmsolitar}' terminal. 
Affinities. From the manner in which Diapensia w^as associated by 
Brown {Prodrorrms 482.), when he separated it along with Hydroleaceae from 
Convolvulacese, it has been generally supposed that this profound Botanist in- 
tended to refer Diapensia to the former of those orders. But upon looking 
again at the passage in question I perceive that it does not necessarily bear the 
interpretation that is usually put upon it, and this has led me to reconsider 
the subject. The result has been a persuasion that Diapensia is in reality 
nearer Polemoniacese than Hydroleaceae, and essentially distinct from both. The 
more immediate points of resemblance with Hydroleaceae consist, firstly, in 
Diapensia having the filaments petaloid, and originating not from within the 
