LETTER TO THE GEOLOGIST-IN-CHARGE. 
LAFAYETTE COLLEGE, 
Easton, Pa., January 15, 1874, 
Sir: In lieu of a simple list of the plants obtained in Colorado during 
the explorations of last summer, I have the honor to present you here- 
with a condensed Synopsis of the Flora of the Territory, prepared in con- 
junction with Prof. John M. Coulter of the Survey. 
The work is based chiefly on collections made, in 1861 and succeeding 
years, by Dr. C. C. Parry, whose indefatigable labors have added so 
much to our knowledge of the flora of the region; in 1862, by Messrs. 
Hall and Harbour; in 1867, by Dr. W. A. Bell, of Manitou Springs; in 
1868, by Dr. F. V. Hayden; in 1869, by B. H. Smith, Esq., of Denver; 
in 1871, by Dr. George Smith and W. M. Canby, Esq.; in 1871 and 1873, 
by Messrs. Meehan and Hooper; in 1872, by J. H. Redfield, Esq.; in 
1872 and 1873, by T. S. Brandegee, Esq., of Cation City, Rev. E. L. 
Greene, of Pueblo, and T. C. Porter; and in 1873, by J. M. Coulter. 
The plan followed in the Synopsis is that of Mr. Watson in his excel- 
lent Catalogue, volume V of Clarence King’s Report. Descriptions are 
given of all the orders, genera, and species not contained in Gray’s 
Manual, Chapman’s Flora, and other botanies of the States east of the 
Msiiasi opi River. 
For the elaboration of the Musci and Hepatice we are greatly indebted 
to Leo Lesquereux, Esq., of Columbus, Ohio; of the Lichens, to Henry 
Willey, Esq., of Amherst, Mass.; and of the Fungi, to Charles H. Peck, 
Eaq., of Albany, N. Y. 
Thanks are due also to Dr. Gray and 8. Watson, Esq., of Cambridge, 
- Mass., and Dr. George Thurber, of New York City, for kindly assistance 
in the determination of difficult and doubtful species; and to J. H. nee 
field, esq., of Philadelphia, for valuable services rendered. 
To Mr. Brandegee, for his large and fine collections from the southern 
part of the Territory, and to the Rev. E. L. Greene, for lists and speci- 
mens of rare species, we are under special obligations. 
References to the authorities consulted and used are to be found at 
the proper places in the body of the work. 
I regret that circumstances have prevented the completion of an intro-_ 
ductory article on the geographical distribution of the plants embraced 
in this synopsis. 
THOS. C. PORTER. 
Dr. F. V. Haypen, U. 8S. Geologist. 
