and distinct characteristic of the group Echinocereus ( in which I include only the 

 northamerican and mexican species. The Cereus strigosus, candicans, etc. Belong, 

 according to their flowers to the group Echinopsis ( as defined by Juecar). In all the real 

 Cereus, of which I have observed a large number, the flowers always come out of the 

 upper part of the areola itself and never from a crevasse in the epidermis. You have 

 generalized too much a characteristic that you without doubt observed only in the 

 Echinocereus. 



One frequently must not generalize the features that one had observed in one or several 

 species, but that can be found in other species. In this manner and to mention yet another 

 example you say in the generic features of the Opuntia "open only in sunlight". However I 

 observed on the shores of the Rio Grande that the flowers of the Opuntia frutiscens, don't 

 have their petals completely open until the middle of the night. I did not frequently have 

 the opportunity to sleep among Opuntia in bloom. Therefore I was not able to verify this 

 fact in other species except in the Opuntia fructiscens in which I observed with accuracy 

 and recorded it explicitly in the diary of my trip. 



I finish my letter already quite lengthy, by offering a seed (extra curricular) of a species of 

 Cylindropuntia, named by Lemaire Opuntia acracantha. This comes from the area of 

 Mendoza which I brought back together with the Opuntia diademata and calva that 

 evidently belong to the same group just like the Opuntia sulphurea, Cereus strigosus, 

 Cereus, candicans, Echinopsis campylacantha and formosa, etc. I examined these plants 

 in Paris on the 8th of last month and found only one seed that I send you with this 

 communication and pray that you will return it to me. This seeds is virguliform and for me 

 constitutes a new type among the Opuntia and will certainly interest you. I wanted to give 

 you the pleasure of drawing it, but I ask you to please send me the sketch of the embryo. 



I will send this letter with the next Courier. While awaiting news from you, soon, I again 

 send you my most affectionate greetings. 



Alb. Weber 



translation by- Manfred Thurmann 



