Alyxia, Banks. 
Gynopogon, Forst. 
Ophioxylon, Burm. 
Willughbeia, Roxb. 
Ancylocladus, Roxb. 
Syringosma, Mart. Dissolena, Lour. Kopsia, Bl. 
Adenium, Ehrenb. Leuconotis, Jack. Helygia, Bl. 
Anabata, Willd. Cyrtophyllum, Rwdt. Hasseltia, Bl. 
Systrepha, Burch. (57) Cereocoma, Wall. Picrophleeos, Bl. 
Pacouria, Aubl. Cryptolepis, Wall. Chilocarpus, Bl. 
Couma, Aubl. Orchipeda, Bl. Rhazya, Decaisne. 
Somewhere here seems to be the station of the little known 
RETZIACE^. 
Bartl. Ord. Nat. (1830). 
Tlie plants upon which it has been proposed to construct this group are 
very little known. They appear to differ from Apocynacese principally in the 
aestivation of their corolla not being valvate, and have assuredly no relation 
whatever to Polemoniaceae. Retzia has in some measure the habit of Cerbera 
Thevetia. 
GENERA. 
Retzia, L. 
Lonchostoma, Wikstr. 
Order CCXXIII. ASCLEPIADACE^. 
Apocyne^, Juss. Gen. 143. (1789) in part; DC. and Duby Bot. Gall. 323. (1828). — 
Asclepiade^, R. Brown in Wern. Trans. 1. 12. (1809) ; Prodr. 458. (1810); Royle 
Jllust. 272. (1835) ; Wight's Contributions to the Botany of India, No. 2. p. 77. (1834) . 
Essential Character. — Calyx 5-divided, persistent. Corolla monopetalous, hypo- 
gynous, 5-lobed, regular, with imbricated, very seldom valvular, aestivation, deciduous. 
Stamens 5, inserted into the base of the corolla, alternate with the segments of the limb. 
Filaments usually connate. Anthers 2-ceiled, sometimes almost 4-celled in consequence of 
their dissepiments being nearly complete. Pollen at the period of the dehiscence of the 
anther cohering in masses, either equal to the number of the cells, or occasionally cohering 
in pairs and sticking to 5 processes of the stigma either by twos, or fours, or singly. Ova- 
ries 2. Styles 2, closely approaching ‘each other, often very short. Stigma common to 
both styles, dilated, 5-cornered, with corpusculiferous angles. Follicles 2, 1 of which is 
sometimes abortive. Placenta attached to the suture, finally separating. Seeds numerous, 
imbricated, pendulous, almost always comose at the hilum. Albumen thin. Embryo 
straight. Cotyledons foliaceous. Radicle superior. Plumule inconspicuous. — Shrubs, or 
occasionally herbaceous plants, almost always milky, and often twining. Leaves entire, 
opposite, sometimes alternate or whorled, having ciliae between their petioles in lieu of 
stipules. Flowers somewhat umbelled, fascicled, or racemose, proceeding from between 
the petioles. R. Br. 
Anomalies. Periploca and some others have granular pollen. Corolla valvate in 
Leptadenia. 
Affinities. So closely are these plants allied to Apocynaceae, that the 
affinities of the one are precisely the same as those of the others ; I shall 
therefore, in this place, speak of the difference between those two orders, and 
of the peculiarities of that more immediately under consideration. Brown, 
who distinguishes them, admits {Flinders, 564) that they differ solely in the 
peculiar character of their sexual apparatus ; but this is of so unusual a kind 
in Asclepiadaceae, that it justifies a deviation from the general rule, that or- 
ders cannot be established upon sohtary characters. In Apocynacese the sta- 
mens are distinct, the pollen powdery (that is to say, in the ordinary state), the 
stigma capitate and thickened, but not particularly dilated, and all these parts 
