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Ch. XVIIL] CLASSIFICATION. 109 
CRUCIFORM FLOWERS. 
461. These are such flowers as have a calyx consisting of 
four leaves, and a corolla composed of four petals; each petal is 
fastened to the receptacle or bottom of the calyx by a narrow 
part called che claw. In the centre of the flower is a single 
pistil long and cylindrical; the stigma is oblong, and divided 
ito two parts, which are reflexed or bent back on each side. 
Each petal is placed between two leaves of the calyx; this al- 
ternate position is always seen in flowers where the number of 
petals equals the number of leaves of the calyx. 
462. The cruciform flowers have six stamens, two of which, 
standing opposite to each other, are shorter than the remaining 
four, which always stand in pairs. This inequality in their 
length determines them to be in the class Tetradynamia. 
463. The germ soon becomes a long pod, called a silique, or 
a short, thick one, called stlicula; this difference in the length 
of the pods constitutes the distinction of the two orders of the 
class in which they are placed. 
464, The plants belonging to this class are herbaceous, the 
leaves are alternate; the Cabbage, the Mustard, the Radish, 
and Stock-gilly-flower, belong to this family. They are found, 
on a chymical analysis, to contain some aitphust 
461. What are cruciform flowers 2 
462. What is said of their stamens? 
463. What is said of the germ ? 
464. What of the leaves, &c.? 
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