THE PHILIPPINE 
Journal of Science 
C. Botany 
Vol. VII. 
SEPTEMBER, 1912 
No. 4 
THE RELATION OF RAFFLESIA MANILLANA TO ITS HOST. 
By William H. Brown. 
{From the Botanical Section of the Biological Laboratory ^ Bureau of Science, 
Manila, P. /.) 
The genus Rafflesia is particularly interesting on account of 
the large size of its flowers and the great reduction of its veg- 
etative parts. A flower of Rafflesia arnoldi R. Br., according to 
a description by Arnold in a letter to Robert Brown,^ measured 
a yard across and sprang from a root about the size of two 
fingers. Brown described the flower as parasitic on a species of 
Cissus and thought that part of the base was derived from the 
host. This opinion he later confirmed ^ and showed that the 
shoot of Rafflesia consisted of a short thick stalk terminating 
in a single large flower, around which, in its early stages, there 
were a number of bracts ; and that the base of the shoot was em- 
bedded in a cup-shaped mass of tissue formed by the host. The 
general relation of the parts of the flower and host is shown in 
figure 3 which represents an expanded flower bud of Rafflesia 
manillana. Robert Brown's drawings show the young buds 
covered by the bark of the host. 
'Brown, R. An Account of a New Genus of Plants, named Rafflesia. 
Trans. Linn. Soc. 13 (1842) 201-234. 
'Brown, R. Description of the Female Flower and Fruit of Rafflesia 
Arnoldi, with Remarks on its Affinities; and an Illustration of the Structure 
of Hydnora Africana. Trans, Linn. Soc. 19 (1845) 221-239. 
U1784 209 
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