TRANSACTIONS OF THE SECTIONS. 101 
On he Structure and Affinities of Orobanchacee. By Dr. Linviey. 
Professor Lindley made some remarks “ On the structure and affini- 
ties of Orobanchacee.” He stated that this order had been usually 
placed near Scrophulariacee, and in his “ Natural System” he had in- 
cluded it in the Scrophulal alliance. In their didynamous stamens, 
superior ovary, and monopetalous flowers, they resembled Scrophulari- 
aceeé. Schultz had placed this order near Gentianacee, on account of 
their fruit and placentation resembling those of this order. Other 
botanists had placed Orobanchacee near Monotropacee, on account 
of their membranaceous foliage and parasitical habits. There was one 
important point, in which they differed from Scrophulariacee, which 
was the position of their carpels, with respect to the axis of inflores- 
cence. In Orobanchacee, the carpels were right and left, or perpen- 
dicular to the axis, whilst in Scrophulariacee they were fore and aft, 
_ or parallel to the axis. This pointed out another affinity-with Genti- 
anacee, which had its carpels in the same position. With regard to 
its affinity to Monotropa, there was a point which had been much over- 
_ looked by botanists, the presence and absence, or large and small 
quantities, of aloumen in the seed of plants; he had found this a very 
constant character, and one of the best for indicating the affinities of 
plants. Both Monotropacee and Orobanchacee were distinguished 
for a minute embryo, lying in a large quantity of albumen. Monotro- 
pacee was a polypetalous order, but its structure generally compelled 
botanists to place it amongst monopetalous plants, near Pyrolacee and 
Ericacee. He remarked by the way, that the division of plants, ac- 
cording to the presence or absence, cohesion or non-cohesion, of the 
petals, was very artificial, and hoped that it would soon be abandoned. 
He thought that the affinities of Orobanchacee were stronger with 
Monotropacee, Pyrolacea, and Gentianacee, than with any other 
orders. The Professor then made some remarks “ On the Placentation 
of Orobanche,” which he said had made him doubt the correctness of 
the present theory of the situation of the placenta. It was generally 
supposed that the seat of the placenta in the carpellary leaf was its 
margin, so that it would be necessarily placed alternating with the 
dorsal suture of the carpel. Exceptions, however, frequently occur, as in 
Parnasia, Papaver, &c.; and the placenta is spread over the whole 
surface of the carpellary leaf, or on various parts of it. In the carpels 
of Orobanche there are evidently two placentz, but having no commu- 
cation with the margin of the carpellary leaf. He therefore inferred, 
that any part of the surface of the carpellary leaf might become oval- 
ized. He was borne out in this opinion by the fact, that leaves which 
occasionally produce buds, produce them from all parts of their sur- 
face, as seen in Ornithogalum, &c.; the production of buds on leaves 
and ovules in carpels being analogous processes. 
