Е. 273. ] 
IX. On the Structure and Development of the Gynostegium, and the Mode of Fertilization 
in Asclepias Cornuti, Decaisne (А. syriaca, Г.). Ву Tuos. Н. Corry, M.A., F.L.S., 
M.R. I.A., late Assist.-Curator, University Herbarium, Cambridge. 
(Plates XXIV-XXVI.) 
Read 7th June, 1883. 
I. DEVELOPMENT. 
THE structure and mode of fertilization of the flowers in the genus Asclepias and, 
indeed, in the natural order Asclepiadez in general, have proved somewhat of a botanical 
enigma, although they have received the attention of botanists of greater or less repute, 
and have formed the object of numerous and varied speculations and researches ever since 
the days of Dillenius. The mode in which the parts of the flower are developed from 
their earliest stages until they attain the adult condition did not, however, engage atten- 
tion until a much later date, the first person to draw attention to it being the celebrated 
English botanist, Robert Brown*. J. B. Payer, in the course of studies for his ‘ Traité 
d'Organogénie Comparée de la Fleur,’ which appeared in 1857, рр. 567-570, pl. 117, also 
made the flower of Asclepias the subject of his investigation. These two writers between 
them left, as might naturally be expected, not a great deal to be done by those who came 
after, and a few of the points they did not settle were, partially at least, set at rest by the 
researches of Hermann Schacht t. 
The mode in which the corpuseula and their appendages are formed had, however, 
never been worked out ; and as the conclusions arrived at by these writers on several 
other very important points were somewhat at variance, I was led to make a further 
and much more extended examination of this portion of the subject. In treating of this 
I will, however, confine myself solely to those points in which my work has afforded me 
results either new or different from those which are most generally accepted at the present 
time. | 
I have devoted my attention mainly to the flowers of Asclepias Cornuti, Dec., but have 
also referred to other species and genera. 
The type of the flower essentially agrees with that which is fundamental in the other 
orders of the group Bicarpellate of Bentham and Hooker, and is represented typically by 
the formula К, Со An; G°. It is actinomorphic, the pentamerous symmetry being only 
broken in the carpels, and most nearly approaches that of the Аросупасее. The two 
ovarian parts of the carpels in their growth never become connate with each other, as is 
the case in the majority of the natural orders forming the group Bicarpellate, e. g. 
е «Оп the Asclepiadee,” Memoirs of the Wernerian Natural-History Society, Edinburgh, vol. 1. 1808-1810, 
pp. 12-58 (read 1809) ; ** On the Natural Order of Plants called Proteacez by Jussieu,” Trans. Linn. Soc. 1809, 
vol. x. pp. 18, 19; Mise. Bot. Works, vol. i. 
t ‘Das Mikroskop; ii. Aufl. p. 166 et seg. pl. 5, English edition, 1853, by Е. Currey, pp. 100-108. figs. 5-27. 
SECOND SERIES. —BOTANY, VOL. II. Т ЗЕ 
