Section IV., 1890. [ 33 ] Trans. R. S. C 



IV. — The Generic Characters of the North American Taxaceœ and Coniferœ. 



By D. P. Penhallow. 

 (Read May 20, 1896.) 



In 1894 a preliminary paper on the "Classification of the North 

 American Coniferœ," based upon the anatomical characters of the wood, 

 was presented to this society, but reserved for future publication. Dur- 

 ing the intervening two years extended opportunities for verification and 

 comparison have been otfered, and much labour has been expended in 

 the revision of details and the elimination of possible sources of error. 

 In the present paper it is designed to give an account of those characters 

 upon which a differentiation of genera may he based, reserving a discus- 

 sion of the specific characters for a future occasion. 



The present classification had its origin in 188U, and is, so far as I am 

 aware, the first attempt of the kind as applied to the North American 

 woods. 



The need of such a work was apparent, not only in the demands 

 arising from an extensive and varied economic application of numex'ous 

 kinds of woods, but in the requirements of the palœobotanist, who sought 

 for some more exact means of defining species and of establishing the 

 relations of fossil woods to those of recent origin, than are to be found in 

 a merely general knowledge of structure. When it is recalled that fossil 

 woods are commonly represented by the more durable jjarts of the fibro- 

 vascular structui"e only — a structure from which many of the anatomical 

 details m:iy have been eliminated by the operation ot decay or the subse- 

 quent alterations attendant upon petrifaction, in consequence of which it 

 becomes of the highest importance that the taxonomic value of such char- 

 acters as are yet recognizable should be capable of exact estimation ; and 

 that wood applied to economic purposes often requires to be recognized 

 under conditions which render the ordinary means of distinction worth- 

 less, it is clear that any system of classification which will admit of a pre- 

 cise limitation of genera and species under all conditions, must jjossess a 

 high degree of value. 



With respect to the application of such a classification to exist- 

 ing species, [the view was held, upon general grounds, that if species 

 could be defined at all, it would be possible to recognize them under 

 all conditions of growth and economic application. How far this view 

 may prove to be correct will be demonstrated by the present treat- 

 ise. With respect to fossil plants, experience shows that the conditions 

 of preservation are extremely varied, so that while a lignite from the 



Sec. IV., 1896. 3. 



