6. PESOMERIA tetragona. 



In a work consisting of indifferent plates, without expla- 

 natory letter-press, published upon the Orchidacese of the 

 Isle of France, Madagascar, and Bourbon, by the late M. 

 Aubert du Petit Thouars, there occurs a curious terrestrial 

 plant, native of two of these islands, and called Epidendrum 

 tetragonum. It is represented as growing about two feet 

 high, with a four-cornered stem, and many oblong plaited 

 acuminate leaves like those of a Phaius, to which moreover 

 the flowers bear some resemblance both in size and form. In 

 the very rare coloured copy of this work, in the possession 

 of the Horticultural Society, the flowers are represented 

 purple, like those of a Bletia ; and upon the whole little doubt 

 could exist of its being related to those two genera. Never- 

 theless it has not been again noticed by any original writer, 

 but has been left among the obscure plants of the work in 

 which it first appeared. 



I was therefore not a little gratified at having an Isle of 

 France plant brought me a few weeks since by Mr. Loddiges, 

 which upon comparison appeared to be identical with the 

 species in question, differing from it in nothing except the 

 leaves being narrower, and the flowers of a pale yellowish 

 brown, instead of a bright rose-colour ; to the latter I attach 

 no importance, as it is by no means improbable that the 

 colour in Du Petit Thouars's book was given from an exami- 

 nation of dried specimens, or from memory. The plant of 

 course was no Epidendrum, a genus unknown in the old 

 world, as the Asiatic Dendrobium is in the new world ; on 

 the contrary it proved a very curious and distinct genus, dif- 

 fering from Bletia, Phaius, and their immediate allies, in 

 having only four, instead of eight pollen masses, and more- 

 over in the labellum being united to the column. The most 

 curious circumstance about it, however, is a phenomenon 

 which I have never seen in any other Orchidaceous plant. 

 The sepals are spontaneously thrown off from the flower 

 shortly after they have expanded, just as leaves are thrown 

 off the stems of many of these plants when they receive a 

 sudden check, and then the petals and labellum only remain 

 to constitute the flower. It even appears from Du Petit 



