73 



observed several have been mentioned in other members of this 

 family. For this reason it is hardly necessary to make some 

 preliminary remarks, the less so because Prof. Penzig in his 

 „Pflanzenteratologie II p. 324 sqq. and in his „ Considerations 

 sur les anomalies des Orchidees" ') has published an excellent 

 survey of the principal monstrosities. We take from Penzig 

 only the so vv^ell marked difference between dimery and pseudo- 

 dimery in the structure of the flower. When the flower is di- 

 merous, both calyx and corolla show the number 2 instead of 

 3, the sepals being placed transverse and the petals (of which 

 one is the labellum) median. In pseudo-dimerous flowers however 

 the inferior sepals have grown together to an apparently simple 

 one which is opposed to the third sepal. The ordinary petals 

 are in this case placed transverse, while the labellum is absent. 

 The latter kind of dimery (Penzig distinguishes other forms be- 

 sides-)) presents itself with perfect distinctness in the Giant-Orchid, 

 Grammatophyllum speciosum, of which I have given an ample 

 description in the „Botanisch Jaarboek" edited by Dodonaea, 

 Ghent, 1894, p. 24. The peculiarity of this plant consists in the 

 pseudo-dimery of the lower flowers of the inflorescence against 

 the trimery of the much more numerous flowers higher up. The 

 same phenomenon has been also found in a couple of other 

 Orchidaceae, which we will deal with further on. For the rest 

 we shall find that several cases have been collected by Mr. Smith 

 of reversion of stamens in the place where the theory of the 

 floral structure requires them either latent or transformed. 



In order to prevent misunderstanding we beg to say that in 

 our descriptions we represent the flower in its position after 

 the resupination or the torsion. 



Arundina speciosa Bl. 



Habitat Southern Asia. 



Coll. Dec. 1895. 



Dimerous flower. 



1) M^moires de la Socidtd natiouale des Sciences naturelles et mathdmatiques de 

 Cherbourg, Tome XXIX, 1894. 



2) Compare the description of Chrysogloasum ornatum p. 74. 



