PREFACE 
From the earliest period of botanical research, to our own time, treatises and 
catalogues have been prepared, each adding something to the information con- 
tributed by its predecessors, until the plant life of the world is more or less 
familiar to us. 
Modern facilities of transportation, as well as the agencies of birds, winds 
and water, tend in so great a measure to disseminate seeds, that it is highly im- 
portant to keep a record both of the new forms introduced and of those that have 
disappeared, and of the habits and variations of them all. 
In publishing the Flora of Cook County, Illinois, and a Part of Lake County, 
Indiana, we endeavor to meet the requirements of many local botanists, who 
have long felt the need of such a record, none having been issued, with the ex- 
ception of Patterson’s State Report, since the publication of Prof. Babcock’s list, 
in Yols. I and II of the Lens (1872-’73). 
The importance of a new enumeration (which includes the phsenogamia and 
vascular cryptogamia) will be seen, when it is realized that about 540 plants not 
recorded by Prof. Babcock, and 182 not mentioned by Patterson, are included in 
the present catalogue. It should be stated, however, that of the plants 
omitted by Prof. Babcock, many are species formed since his time, species in- 
troduced by cultivation or otherwise, and now growing spontaneously, or varieties 
of recent formation. There are also some species enumerated by Prof. Babcock, 
but not reported as growing within our limits ; the area included by him em- 
bracing a territory having a radius of forty miles from Chicago. 
Fifteen plants are recorded that are not included in the 5th Ed. of Gray’s 
Manual: 
Lepidium sativum, L. 
Cleome integrifolia, T. & G. 
Lechea minor, L. 
Gaura parviflora, Dougl. 
Carum carui, L. 
Grind elia squarrosa, Dunal. 
Tragopogon porrifolius, L. 
Tragopogon pratensis, L. 
Lactuca lucopheea,var. integrifolia, Gray. 
Solanum carolinense, L., var. florida- 
num, Chap. 
Solanum rostratum, Dunal. 
Gerardia purpurea, L., var. paupercula, 
Gray. 
Anychia capillacea, D C. 
Potamogeton fluitans, Roth. 
The following species not being recorded in the 6th Ed. of Gray’s Manual, 
a description of them is given in this catalogue: Lepidium sativum, L., Lechea 
minor, Lam , var. stricta, Leggett and Solanum carolinense, L., var. floridanum, 
Chap. 
Cornus baleyi, Coult. & Evans, and Cnicus hillii, Wm. Canby, also unre- 
corded, are recent species. 
It has been our plan, with the assistance of co-laborers, by exhaustive field 
work and examination of private lists and herbaria, not only to catalogue the 
plants growing in our area, but to give information concerning their natural 
