Plate XXXIX. 



ONCIDIUM PECTORALE 



O. pectoraht pseudobulbia »vati, oompwssia tulcafe diphyllk, foliis oblongfe «1, 

 turns papyroceis scupo a basi paniculate brovioribua, sopalfe latcralibus ecmi- 

 connatis pctnluquc obovatfc majoribus undnlatis, labolli lobis lataralibuB iiania 

 intermedio maximo convcxo undulato bilobo, crislfl ovaui dcprcesfl acuminata 

 margin© verrucosa tuberculieqne numcrwis in frusti forma ordinal circum- 

 datJi, columnai alis tmncjitis. 



The wood* of Braril. .coming with plants of boamifnl form, rich colour. and singular structure 

 Lave furn.sl.cd th,s. <!.«- handsomest of the ydlow Oncidiums. I am indebted for my knowledge of 

 ■1 to Jamc* Wcntwortl, llullcr. Esq. of Downes near Exeter, from whom I received a specimen „nd 

 drawing in April. 1840. will) the following memorandum : 



'■ I have ascertained that it was imported from Rio do Janeiro, ami it seem* to mo to resemble 

 ». halm the O. Forbcsii which I received at the same lime, hut in the structure of the leaves it 

 aH.roael.es closely to O. flexuosnm. The i*cudo-bull» arc also furnished with leave* at their bftM 

 as well as at their ,.oint. which is the ease with Q.$mmm,\m I append not uniformly the 

 ease wah all Onc.diums, It seems to me aUo that the anther, which form, „ it were the termination 

 of the column and surmount* the stigma, (in which [hero is a considerable Mention of honey) is 

 more fully developed than I have observed it to bo in the flower, of other Oneidiums ; and in this 

 respect the flowers remind me of an effect I formerly observed in that of Pcristeria data. My 

 gardener accidentally bruised the anther of one of the flowers in measuring them with a carpenter's 

 rule, and I observed that the flower drooped immediately, and died in the course of two days. The 

 other flower* are as fresh as on the day in which they firs, expanded, and 1 hope to preserve then, 

 in full beauty for n month longer by keeping the plant in the shade." 



The arrangement of the tubercles at the base of the lip is represented in the figure at the (eft- 

 band corner of the plate. It is difficult to describe, and may be compared for general appearance to 

 an old.fash.oned ladies stomacher, studded with little knots \ henee the name. 



The eirenn.st.we alluded . by Mr. Butler is a singular phenomenon common in the whole 

 Orchidaceous order. He found Km. when the anther was disturbed the flower quickly died This 

 was not because the anther wan removed, but because in removing the anther the pollen was brought 

 .nto contact with the stigma, and thus the act of fecundation was accomplished. In general from 

 the absence of insects, or of those other disturbing causes to which Orcbidacom arc exposed in' their 

 native places, the pollen cannot come into contact will, the stigma, and so long as this is prevented 

 the flowers of many species will retain their freshness for weeks, as if in expectation of that event 

 for which they were created. But as soon as the act of fecundation is accomplished, that is to say 

 iron, twelve to twenty-four hours after the pollen touches the stigma, the flowers colla.,sc. ,he bright' 

 colour, become dun, the ovary begins to enlarge, ami ,l,e beauty of the flower is gone. 







