MEDICINAL PLANTS. 161 
effective weapons, and they should be used to prevent, as far as 
possible, the development of seeds. 
V. Medicinal Plants. 
This is by no means the least interesting part of the flora. 
The products of more than forty native species are recognized 
as official by the U. S. Pharmacopzia. In addition to these, 
many species are used as substitutes, or as home remedies. 
Some of the official species are not found in sufficient quantity 
to be of commercial value, but their occurrence in the county is 
of interest. Various parts of plants contribute the official pro- 
_ duct, and the best séason of the year for collecting the materials 
will vary with the part used. It may be stated as a general rule 
that rhizomes and roots should be collected in late summer or 
early autumn; the bark of Ulmus in early spring, and other 
barks (of both root and stem) in spring or autumn; the herbs 
and leaves are usually best just before flowering has commenced; 
the flowering tops when the first flowers are about to fruit; the 
flowers just after opening; and the fruits when mature. The 
distribution in the county, and the habits of the species dis- 
cussed in this connection are given in the annotated list. The 
species are here grouped according to the part of the plant 
yielding the official drug, the official name preceding the name 
of the plant, which is given in parenthesis. 
1. The herb (leaves and young stems).—Oil of Erigeron 
(Leptilon canadense), Pulsatilla (Pulsatilla hirsutissima) and 
Scutellaria (Scutellaria lateriflora). 
2. Flowering tops—Hupatorium (Eupatorium  perfolia- 
tum), Hedeoma (Hedeoma pulegeoides) and Lobelia (Lobelia 
inflata). 
3. Leaves.—Chimaphila (Chimaphila uwmbellata), and Rhus 
Toxicodendron (Rhus radicans), the latter fresh. 
4. Flowers—Sambucus (Sambucus canadensis). 
5. Fruit—Rhus Glabra (Rhus glabra), Humulus (Humulus 
lupulus), Oil of Juniper (Juniperus communis) and Raspberry 
(Rubus occidentalis and strigosus). 
6. Seeds.—Sinapis Nigra (Brassica nigra). 
7. Bark of stem—Hamamelis Bark (Hamamelis virgini- 
ana), Canada Balsam (from Abies balsamea), Oil of Betula 
it 
