352 CALIFORNIA ACADEMY OF SCIENCES. 



under favorable conditions of growth, present the largest 

 trees known in this group, frequently attaining a height of 

 eighty feet, with a smooth columnar trunk three feet in 

 diameter at base — observations during the present season 

 have brought to view such peculiar and hitherto unnoticed 

 botanical characters as to justify their presentation before 

 a meeting of the California A.cademy of Sciences. 



It must be premised that Nuttall's original description 

 of Alnus rlioinhi'/oUa, contained in Am. Sylva., Vol. II., 

 p. 49, was taken from a leaf branch without flower or 

 fruit, collected by Nuttall himself in the vicinity of Monte- 

 rey, probably in April, 1836. Since then the name has 

 been generally, and no doubt properly, applied to the com- 

 mon California alder, of the western and interior districts, 

 extending from Oregon to Southern California. As such, it 

 is included by Watson in Bot. Cal. II. p. 80. 



Probably about twelve or fifteen years later than Nuttall's 

 description above referred to. Dr. Torrey, in the Botany of 

 the Mexican Boundarj^ Survey, p. 201, described Alnus 

 ohlongifolia from specimens collected by C. Wright in New 

 Mexico, the specific character being mainly based on the 

 foliage; subsequently Mr. Watson identifying Dr. Torrey's 

 species with the Southern California Alnus, included A. 

 oblo}ig{/olia,Ton\, in Bot. Cal. p. 81. In making a critical 

 comparison of the description of these two species as 

 given therein it is noticeable that the points of differ- 

 ence are very slight, and might easily be comprised within 

 the limits of ordinary variation. 



An equal difficulty has been experienced by field observ- 

 ers, and from a somewhat extended observation for several 

 years, I have never yet been able to draw a clear line of 

 distinction between these two species as laid down in 

 botanical works. Accordingly, in order to satisfy myself 

 on this doubtful point, I have undertaken the present sea- 

 son to make a series of observations, including the earliest 

 growth and flowering, some of the results of which thus 

 far reached, may be briefly noted. 



