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ASCLEPIADA CEAE 
drawing it up removes the pair of pollinia. The threads as they dry 
contract on the inner side till the pollinia meet, thus closely clasping 
the insect’s leg. In drawing the leg through a similar slit in another 
fir. the pollinia catch on the stigmatic under-surface of the stylar head. 
(Cf. Apocynum, which shows an approach to this mechanism.) 
The backs of the anthers bear as a rule curious appendages 
(cuculli) forming a corona . In some cases the corona springs from 
the corolla. It may consist simply of small teeth, or be more complex 
in structure, as in Asclepias and Ceropegia. It often takes up the 
functions of secreting and storing the honey. 
The ovary is bilocular, superior, with oo anatropous ovules, pen- 
dulous from the ventral placentae. The fruit consists of a pair of 
follicles ; the seeds are usually crowned by a tuft of hairs for wind- 
carriage. Endosperm slight, cartilaginous. 
Classification and chief genera (after K. Schumann) : 
I. PERIPLOCOIDEAE (pollen in tetrads; translator spoon- 
like). 
1. Periploceae : Streptocaulon, Periploca. 
II. CYNANCHOIDEAE (pollinia; corpusculum &c.). 
2. Asclepiadeae (pollinia pendulous on threads): Asclepias, 
Cynanchum. 
3. Seca 7 ?ioneae (pollinia erect or horizontal, 4 in each anther): 
Secamone (only genus). 
4. Tylophoreae (do. but 2 in each, erect) : Ceropegia, Stapelia, 
Stephanotis, Hoya. 
5. Gonolobeae (do. but 2 in each, horiz.) : Gonolobus. 
The order is closely related to Apocynaceae, the only absolute 
character of distinction being the presence of translators in Ascl.; 
otherwise the two sub-orders of each form a corresponding series, and 
the lower one in each is almost as nearly related to the corresponding 
one in the other order as to the higher group in its own order. A. 
are placed in Contortae by Eichler (Warming), and in Gentianales by 
Benth. -Hooker. 
Asclepias Linn. Asclepiadaceae (11. 2). 80 sp. Am., Afr., chiefly in 
the U. S. (silk- weeds). Erect herbs with umbellate infls. which 
spring from the stem between the petioles of the opposite leaves 
(cf. Cuphea), or above or below this point. Two explanations are 
forthcoming, but which is right the evidence at present available does 
not show. Either the infl. is really axillary to the leaf below it 
and is ‘adnate’ to the stem (as in Cuphea), or it is the termination 
of a shoot, and the stem is really a sympodium. 
The cuculli of the anthers form little pockets, into which honey is 
poured by the horn-like nectaries that project from them. Insects 
walking over the flowers and sipping honey frequently slip their legs 
down the sides of the gynostegium, and in drawing them up catch in 
the slit between two anthers and remove the pollinia (see order for 
