278 THE PLANT WORLD. 



PREPARATION OF SPECIMENS OF OPUNTIA. 



By David Griffiths, Ph.D., 

 U. S. Department of Agriculture. 



We fancy that difficulty of preparation accounts in the largest 

 measure for the dearth of specimens of the genus Opuntia in all 

 of our large herbaria. That the preparation of specimens is 

 difficult there can be no question, but it is not true that good ones 

 can not be prepared ; indeed the different species lend themselves 

 to the collector's art much more readily than do the succulents 

 in general. The impression should not be given that no collec- 

 tors have made specimens of these plants, for some have pre- 

 pared beautiful ones, but poor material or none at all is the rule. 

 Our large herbaria are beautifully supplied with other easily pre- 

 pared plants with which these grow, but the dearth of material 

 in this and allied groups is appalling. Some botanists have con- 

 tented themselves with forwarding cuttings to some garden or 

 conservatory, — an admirable plan so far as it goes — but this form 

 of record is not a permanent one. From these specimens, some- 

 times supplemented by a few meager notes by the collector, de- 

 scriptions have been drawn which in many cases do not describe. 

 The cuttings have failed to grow, or growing for a time, have 

 lost their identity and have had their labels shuffled in the proc- 

 esses incident to all cultural work, or they have " gone the way 

 of all living," so that in any case there is no type specimen to 

 which botanists may refer questions of doubt. As an illustration 

 of this point we might mention the case of Opuntia treleasii pub- 

 lished in 1896. Even with the care exercised in such an admir- 

 ably conducted institution as the Missouri Botanical Garden, the 

 type of this species has disappeared. It is true that we know 

 the type locality, and the collector remembers much about the 

 characteristics of the plant, but the species is very variable in the 

 immediate type locality so that it is difficult even now to deter- 

 mine the exact form which was originally described. Dead 

 specimens should, therefore, back up descriptions of new species 



