Darwin- Wallace Celebration. 69 



native of Colombia, and grows in at least three distinct districts, at 

 an altitude of about 7,500 to 8,800 feet, and in a fairly temperate 

 climate. It grows more or less in company with several other 

 species, with some of which it hybridises. 



For many years it was imported from what is known as the Pacho 

 district, on the Eastern Cordillera, in which it was originally 

 discovered, by Hartweg, and with it three other species and a 

 number of curious intermediate forms, some of which have been 

 regarded as varieties of it and others as natural hybrids. The three 

 other species mentioned are 0. gloriosum, 0. luteopurpureum, and 

 0. Lindleyanum, with all of which it hybridises ; and it is an 

 interesting fact that all the six possible combinations between the 

 four species known to grow together have now been recognised 

 They may be enumerated as follows : 



0. crispum x 0. gloriosum = 0. Andersonianum. 



0. crispum X 0. luteopurpureum = 0. Wilckeanum. 



0. crispum X 0. Lindleyanum = 0. Coradinei. 



0. gloriosum x 0. luteopurpureum, = 0. Mulus. 



0. luteopurpureum x 0. Lindleyanum 0. asuminatissimum. 



0. gloriosum x 0. Lindleyanum = 0. prcevisum. 



The first four of these hybrids are remarkably variable, and 

 certain forms which have been referred to them are difficult to 

 separate from others which are referred to 0. crispum, which is also 

 very variable in this district. So numerous are these intermediate 

 forms, and so perplexing their affinities, that the species have been 

 spoken of as " confluent in series." It is now clear that this is due 

 to the further intercrossing of the hybrids with the parent species, 

 as is explained later. 



A second district for Odontoglossum crispum was discovered by the 

 late Consul Lehmann, on the Central Cordillera, near Popayan, 

 some 200 miles distant from the original locality, where it occurs 

 in a quite distinct form, which was described by Beichenbach as 

 0. crispum var. Lehmanni. The flowers are smaller, with narrower 

 segments, and the inflorescence branched. Here the species 

 shows little variation, and no natural hybrids are certainly 

 known to occur, while it is significant that there is a complete 

 absence of those richly blotched and spotted forms which are 

 found in the Pacho district, and which are so highly prized by 



