CLASS TETRAD YNAMIA. 
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possess powerful medicinal properties ; as the foxglove, {Digita- 
lis,) and the cancer root; {Epiphegus.) They are in general 
a beautiful collection of plants; few flowers are more splendid 
than the Gerardia and the Trumpet-flower. These flowers are 
found in the natural order personatae, of Linnaeus. 
As plants of this class are numerous in every part of the l ni- 
ted States, you will have no difficulty in procuring them for an- 
alysis; they are not usually found in blossom until the middle 
of summer. 
CLASS XIV TETR ADYNAMIA. 
In this class we find the cruciform plants, or such as have 
four petals in the form of a cross ; the stamens are six, four of 
which are longer than the remaining two ; the calyx has four 
leaves. The orders in this class are two, depending on the com- 
parative length of the pods ; this distinction is not so definite as 
that which marks the orders of the class Didynamia. Plants 
of this class are not poisonous ; many of them furnish us with 
useful food. 
SILICULOSA. 
The First Order contains plants which produce a short and 
round pod ; a distinction in this order is made between such 
plants as have pods with a notch at the top, and such as have 
none, or are entire. 
The pepper grass, (Lepidium,) and the shepherd’s purse, 
(Thlaspi,) afford examples of this order. These and the remain- 
ing plants found here, belong to the natural order Siliquosce, or 
such as have silique pods, the properties of which are nutritious 
and medicinal. 
SILiaUOSA. 
The Second Order contains such plants as have long and 
narrow pods; as the radish and mustard. The cabbage, (Bras- 
sica,) is an exotic ; it contains the turnip species. Thege be- 
long to the same natural family of plants as the first order. 
The whole are included under the G3d order of Jussieu, the 
Crucifer a. This order is in Jussieu’s 1 3 th class, having seeds 
dicotyledonous, corollas polypetalous, and stamens hypogynous. 
In this lecture we have pointed out to you the most impor- 
tant characters of the two classes, which depend upon consid- 
Class Tetradynamia — General character — Order Siliculosa — Order Sili- 
quosa — Recapitulation. 
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