









206 



ME. R. A. ROLFE ON THE 













On the Sexual Forms of Ca t as e tu rn, with special reference to ttfe 

 Researches of Darwin and others. By 11. Allen KcffirE, 

 A.L.S., Assistant in the Herbarium of the Royal Gardens, 

 Kew. 



[Bead 21st March, 1889.] 

 (Plate VIII.) 



In the sixth volume of the Journal of this Society, in 1862 

 (pp. 151-157), appeared a noteworthy paper by Darwin, bearing 

 the title " On the Three Remarkable Sexual Forms of Catasetum 

 tri&entatum, an Orchid, in the possession of the Linnean 

 Society."* The purport of this paper was to show that the 

 species in question had been observed to produce three distinct 

 kinds of flowers, belonging to the same number of supposed 

 genera, all on the same plant. Each of the three forms was 

 represented by a woodcut. The explanation given of this curious 

 phenomenon was that the three forms represented, respectively, 

 the male, female, and hermaphrodite states of the same species. 



This paper was a remarkable one in many respects. In the first 

 place, it established conclusively the fact — already more than sus- 

 pected by Schomburgk — that the so-called sportive character ot 

 Catasetum, or the curious habit of its species of suddenly pro- 

 ducing flowers of a totally different kind (usually termed 

 " monsters ") on the same plant, was simply an abnormal combi- 

 nation of different sexual forms in the same individual. In the 

 second place, it described, fully aud graphically, the remarkable 

 structural adaptations by which self-fertilization was prevented 

 and cross-fertilization (by insect agency) secured. And, in the 

 third place, it indicated a condition of things which, I venture to 

 think, is unparallelled in the entire Vegetable Kingdom, namely 

 the production, by one and the same species, of one kind oi 

 flowers, wholly male, of a second kind, wholly female, dependent 

 on a highly complex process for their fertilization ; and of yet a 

 third kind, hermaphrodite in character, yet not cleistogamous — in 

 other words, still highly specialized and incapable of self- 

 fertilization. 





















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The aocounts given by the same author in his work ' On the Various Con- 

 trivances by which British and Foreign Orchids are Fertilized by Insects/ ed. 1, 

 pp. 236-247, and in Ann. Sc. Nat, ser. 4, xix. pp. 247-255, t. 12. fig. A, are 

 substantially identical. 





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