INTRODUCTION. xiii 



ties as given on the labels should be recorded instead of merely the 

 counties. A gazetteer explaining the localities is given as an appen- 

 dix. This was partly prepared by the author, but completed, cor- 

 rected and revised at Fort Collins, principally by Mrs. L. G. 

 Carpenter. 



As stated before, the keys were mainly abstracted from those of 

 the author's larger work in preparation, i. e., as far as these were 

 made. As the Manual will be a purely scientific work, the keys 

 are perhaps drawn in a more technical style than desirable in a 

 catalogue to be used principally by the local and the amateur 

 botanists of Colorado and by tourists. To reconstruct the keys 

 would involve too much extra labor. Besides it is hard or rather 

 impossible to use only plain English without losing the fine shades 

 of distinctions which can be expressed by more technical words. 

 For example, the only purely English word for the technical words : 

 " villous," " floccose," " pannose," " tomentose," " tomentulose," etc., 

 is " woolly." 



The measurements in the keys are given in the metric system, a 

 system now used by nearly all the scientific departments of the 

 United States Government and of most colleges and universities of 

 this country. In the English system formerly used in descriptive 

 botany, etc., the inch was divided into 12 lines. It is very hard to 

 find a ruler now-a-days with this division, while rulers with the 

 metric system are to be had nearly everywhere. For those un- 

 familiar with this system, the following comparative table is given. 

 The equivalents are near enough for all practical purposes : 



I mm. = 2-'- inch. i line == 2 mm. 



3 mm. = y^ inch. y^ inch = 3 mm. 



I cm. =^ inch. i inch =25 mm. or 2^ cm. 



5 cm. =^ 2 inches. i span = i dm. 



I dm. = 4 inches. i foot = 3 dm. 

 I m. ^40 inches (nearly) or i yard = 9 dm. 



3^ foot. 1,000 ft. ^300 m. 



The altitudes were also given in meters, but they were changed 

 into feet by the request of Professor Carpenter, who claimed that 

 the people of Colorado, for whom principally the work is prepared, 

 as a rule think of altitudes in feet only. As the United States Land- 

 Office has not as yet adopted the metric system as their standard, 

 the altitudes may just as well be given in feet. This statement is 



