40 
OP THE STEM. 
price! Who would not rather, like the mountain oak, meet the 
storms of hfe firmly rooted in virtuous principles, than to be floated 
along even by the breath of pleasure, without end or aim, forgetful 
of the past, and careless of the future ? To the virtuous, afflictions 
serve but to strengthen them in goodness ; so, 
" Yonder oaks ! superior to ilie power 
Of all the warring winds of heaven do rise, 
And from the stormy promontory tower ; 
While each assailing blast increase of strength supplies." 
We find some roots growing on other plants, and appearing to de- 
rive sustenance from their juices. These are called parasites ; this 
term is often applied to persons who are wilhng to live in depend- 
ance upon others; and so despicable does this trait of character ap- 
pear, that we almost conceive it a kind of meanness, even for a plant 
to live without elaborating its own food. Parasitic plants are com- 
mon in tropical regions ; sometimes many kinds are found upon the 
same tree, presenting a curious variety of foliage. In our climate, 
except in the Cryptogamous family, as lichens, mosses, &c. we have 
but few genera of these plants.* The Dodder and Mistletoe are cel- 
ebrated parasitic plants. 
Some plants grow without roots; these are called air plants : they 
are furnished vrith leaves or stems which seem to inhale, but not to 
e.vhale fluids ; their substance is usually fleshy and juicy; some of 
tliem flourish in the most dry and sandy places, exposed to a burning 
sun; as the Stapelia, sometimes called the vegetable camel. The 
Epidendrum grovvs and blossoms for years, suspended from the 
ceihng of a room, and nourished only by air. 
Many roots, as the rhubarb, vdid-turnip, blood-root, &c. possess 
important m.edicinal properties. The growth of the root is most 
rapid in autumn ; at this season, the sun being less powerful, and the 
air more charged with moisture, the juices condense in the lower 
part of the plant, and nourish it, but as the season becomes cold, 
vegetation is checked ; the winter is the best time to collect roots for 
medicinal purposes, because their pecuhar virtues are then most* 
concentrated 
LECTURE VII. 
OF THE STEM. 
The stem is the body of a plant, whether it be a tree like the oak, 
a shrub like the lilac, or an herb like the poppy ; its use is to sustain 
the branches, leaves, and flowers, and to serve as an organ of com- 
munication between them and the root, conducting from the latter to 
the former, the animal and vegetable substances, salts, and earthy 
matter, which the radicles, by their mouths, suck up for the nourish- 
ment of the plant. The influence of hght and air is, through the 
medium of the stem, conveyed from the leaves to the root. 
* In the vicinity of Troy, I have seen a very beautiful species of the Pterospora, 
growing upon a branch of the whortleberry. Its colour was a bright crimson, which 
contrasted finely with the white flowers and green leaves of the plant on which it 
grew. 
Parasitic plants— Air plants— Proper time to collect roots for medicinal purposes- 
Stem, its use. 
