SoLANALES.] ASCLEPIADACEiE. 625 



and such as are in the usual state of other plants ; this excessive development of the 

 cellular tissue of the stem, and reduction of that of the leaves, occurs in its greatest degree 

 in Stapelia and Ceropegia ; is diminished in Dischidia, the succulence of which is 

 confined to tlie leaves ; and almost disappears in Hoya, 

 the stem of which is in the usual state, but the leaves 

 between fleshy and leathery. 



It has already been stated, under the Order of Dog- 

 banes, that the resemblances found between that Order 

 and Asclepiads seemed to be one of analogy rather than 

 of real affinity ; for the economy of the flowers and seeds 

 in the two Orders are widely different. The amygdaloid 

 embryo of Asclepiads, with hardly a ti'ace of albumen, is 

 entirely different from that of Dogbanes, which is very 

 small, and furnished most abundantly with albumen. 

 The anthei"s and stigma of Dogbanes form no organic 

 union, but they grow into one solid central mass in the 

 Asclepiads, whence proceed other physiological and struc- 

 tural peculiarities. 



Other Botanists do not attach the same importance to 

 these cu'cumstances, and continue to associate the two 

 Orders, adopting the opinion of Bro\vn, who considered 

 that they differed solely in the nature of their stamens Fig. CCCCXX. 



and stigma, the stamens of Dogbanes being distinct with 



powdery pollen, and those of Asclepiads adherent to the table-shaped stigma, the pollen 

 being contained in bags, fonned by the separation of the endothecium. And M. Alph. 

 De Candolle has recently taken the same view of the matter.— ^ww. Sc. Nat. 3. ser. 1. 

 255. He even shows that the distinction found in the stamens and pistil of Dogbanes 

 and Asclepiads is not so positive as it is supposed to be, for there are Asclepiads with 

 stamens free from their very base, and small stigmas, while on the other hand certain 

 Dogbanes have fihform appendages at the end of their anthers, and great glandular 

 stigmas to which the anthers adhere with force. He even thmks that the only precise 

 distinction resides in the pollen, the grains of which are always separate in Dogbanes, 

 always in waxy masses or bags in Asclepiads. The reason why these great Botanists 

 attach small importance to the albumen as a distinction, is doubtless because in certain 

 Dogbanes, such as Cerbera, that secretion is absent, although m the mass of the Order 

 it is most abundant ; but it is, I think, e\-ident that the tendency among Dogbanes is to 

 form albumen in abundance, and that no such tendency exists among Asclepiads. 



Africa must be considered as the great field of Asclepiads, especially its southern 

 point, where vast numbers of the succulent species occupy the dry and sterile places of 

 that remarkable country. In tropical India and New Holland, and in all the equinoc- 

 tial parts of America, they also aboimd. Two genera only are found in northern lati- 

 tudes, one of which, Asclepias, has many species, and is confined apparently to North 

 America ; the other, Cjoianchum, is remarkable for extending from 59° north latitude 

 to 32'' south latitude. A StapeUa is fovmd in Sicily. 



The roots are generally acrid and stimulating, whence some of them act as emetics, 

 as Tylophora asthmatica and Secamone emetica ; others are diaphoretic and sudorific, 

 as the purgative Asclepias decumbens, which has the singular property of exciting 

 general perspiration without increasing in any perceptible degree the heat of the body ; 

 it is constantly used in Virginia against pleurisy. Then- milk is usually acrid and 

 bitter, and is always to be suspected, although it probably participates m a slight degree 

 only in the poisonous quahties of that of Dogbanes, if we can judge from the use of 

 some species as articles of food. Ceropegia ? edulis, Oxystelma esculentum, and two 

 Sarcostemmas, Forskahlianum, and stipitaceum, are all reported to be eatable. The 

 Cow Plant of Ceylon, or Kiriaghuna plant, Gj-mnema lactiferum, yields a mdk of 

 which the Cingalese make use for food ; its leaves are also used when boiled. But 

 very httle is kno\vn about the real quahties of such plants, and as to Oxystelma escu- 

 lentum, Roxbui'gh says he did not find that the natives ever eat it, and Dr. Wight 

 makes the same statement ; adding, however, that in decoction it is used as a gargle 

 for aphthous affections of the mouth and fauces. The root and tender stalks of Hoya 

 viridiflora sicken and excite expectoration. Asclepias tuberosa, or Butterfly-weed, is 

 a popular remedy m the United States for a variety of disorders ; its properties seem 

 to be those of a mild cathartic, and of a certain diaphoretic attended with no inconsi- 

 derable expectorant eff'ect. A decoction of Asclepias curassavica, or Wild Ipecacuanha 

 of the West Indies is used by the Negroes as an emetic and pm-g ative, and is said to be 



Fig. CCCCXX.— Stapelia. 

 SS 



