154 



"Being already in correspondence with Doctor Engelmann 

 regarding certain oaks of middle Illinois, I made mention of the 

 Tradescantia, receiving the following in reply; and it is the 

 earliest of his letters to me which is still preserved. 



" 'St. Louis, Jan. 26, 1870. 

 " 'Dear Sir: — 



I have for many years taken an especial interest in Oaks, and 

 wish to obtain specimens of your Quercus Leana, but if possible 

 with the fruit on the branch. I collect oaks a little before the 

 fruit is ripe, say in September, and run a pin through the cup so 

 as to attach the base of the acorn firmly. If possible, the speci- 

 mens ought to show also the young fruit of the same season and 

 the old maturing one of the last (eighteen months old). And 

 when the tree is easily reached the flowers ought to be gathered 

 (about the first week in May). 



" 'The tall Tradescantia is the only one I have ever seen in 

 cultivation in Europe, where it is the common one, always under 

 Linne's name, T. virginica. I can, as you do, always distinguish 

 the low one, but not by any character of flower or fruit. I find 

 that many years ago I even examined the parts microscopically 

 ;and found the epidermal cells different. I also cultivated them. 

 'One might try and hybridize them, if flowering at the same period. 

 As the modern views make species a less definite entity the im- 

 portance of what is a species and what are varieties lessens 

 •wonderfully. 



" 'I hope you will have a pleasant and successful trip. 



" 'Yours truly, 



" 'G. Engelmann' 



"The concluding sentence of Doctor Engelmann 's letter re. 

 lates to a purpose which I had formed, and which I had men- 

 tioned both to him and to Dr. Gray, of spending the season of 

 1870 in the Rocky Mountains of Colorado. My interest in the 

 vast and then very little known flora of the far -western Terri- 

 tories had been awakened during my early school days, chiefly 

 by occasional readings of the botanical parts of various Pacific 

 Railway Survey Reports. My earliest teacher and companion 

 in botanical studies. Professor Thure Kumlien (I have given a 



