[ 463 ] 



LXI.— ON THE STRUCTUEE OF THE FLOWER OF BONA- 

 TEA SPECIOSA, WILLD. By W. R. M'NAB, M.D., 

 F.L.S., Professor of Botany, Royal College of Science, 

 Scientific Superintendent of the Royal Botanic Garden, 

 Glasnevin ; and Consulting Botanist to the Royal Dublin 

 Society. 



[Eead, May 18, 1885.] 



On the 29th of April, 1885, Mr. F. W. Moore directed my atten- 

 tion to a plant of Bonatea speciosa, Willd, then in flower at the 

 Royal Botanic Garden, Glasnevin. The plant is a native of the 

 Cape of Good Hope, and the specimen in the Glasnevin Garden was 

 obtained from the Leyden Botanic Garden in 1883. As the flower 

 was evidently one of great interest, Mr. Moore kindly sacrificed the 

 whole spike, and I have since examined the structure carefully. On 

 making a direct examination of the flower, without having consulted 

 any book or paper on the subject, I came to the conclusion that in 

 the flower of Bonatea speciosa all the typical parts of a monocoty- 

 ledonous flower were represented, and that therefore the plant was 

 one of singular interest. The three parts of the calyx, the three 

 petals, were present as usual, as well as the one fertile stamen of 

 the outer row. But, in addition, there were two petal-like struc- 

 tures, but more conspicuous than the petals, and these I at once 

 considered to be petaloid staminodes. Next, two gland-like struc- 

 tures attracted my attention, at the base of the staminodes, and 

 these were put down as representing two of the inner row of sta- 

 mens, and a conical fleshy projection on the labellum immediately 

 in front of the spur completed the inner series of stamens. The 

 rostellum and two fertile styles and stigmas projected outwards 

 over the labellum, and thus completed the flower. 



Bonatea speciosa was carefully studied by Darwin from dried 

 specimens (see Fertilization of Orchids, p. 302, et seq.), and he con- 

 siders Bonatea to be an exception in regard to its structure ; but he 

 considers the wide separation of the anther cells to be the cause of 

 the distortion. He also holds the view of all descriptive botanists, 

 that the lateral petals are cleft into two. Further, he points out 



SCIEN. PROC. R.D.S. VOL. IV. PT. IX. 2 S 



