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THE FLOWER.—CALYX.—COROLLA. 17 
b, b). In some cases these bracts are of a green colour, and in 
other respects resemble the ordinary foliage leaves, but usually 
they are distinguished from the leaves of a branch by differences 
of colour, outline, and other peculiarities. The flowers are vari- 
ously arranged upon the peduncle, and to each mode of arrange- 
ment a special name is applied; the term inflorescence being 
used in a general sense to include all such modifications. 
b. The Flower.—A flower in its most complete state of de- 
velopment (fig. 25) consists of four distinct series of organs, that 
is, of two internal or essential organs of reproduction (fig. 26), 
enclosed in two particular envelopes, which are especially de- 
~ signed for their protection, termed floral envelopes (fig. 25). 
The essential organs are called the Andreciwin (fig. 26, ec, ec), 
and Gyneciwm ( figs. 26, sti, and 32, 0, sti); and the floral en- 
velopes are termed Calyx (fig. 25, c), and Corolla, p, p. The 
extremity of the peduncle or pedicel upon which the parts of 
the flower are placed, is called the Thalamus or Receptacle ( figs. 
26, r, and 31, r); but the latter term is more properly applied 
in a special sense, as will be explained hereafter when treating of 
the Peduncle in detail. The four series of organs thus form- 
ing the flower are arranged as four circles, or whorls as they 
are commonly termed, in the following order, from without 
inwards :—1. Calyx, 2. Corolla, 3. Androecium, 4. Gyncecium. 
The Calyx (fig. 25, c) is the whorl or circle of leaf-like 
organs forming the outer envelope of the flower. Its parts are 
called sepals, and these are generally green, and of a less deli- 
cate texture than those constituting the corolla. In texture, 
appearance, and other characters they bear commonly a great 
resemblance to the true or foliage leaves. 
The Corolla (fig. 25, p, p), is the whorl or whorls of flattened 
organs situated within the calyx, and forming the inner enve- 
lope of the flower. Its parts, which are called petals, are fre- 
quently decorated with the richest colours ; by which character, 
and by their more delicate nature, they may be usually known 
from those of the calyx. 
The calyx and corolla are sometimes spoken of collectively 
under the name of Perianth. This term is more particularly ap- 
plied to the flowers of Monocotyledons where the floral envelopes 
generally resemble each other, and are usually of other colours 
than green, i.e. petaloid in their nature (fig. 28). The Tulip, 
the Iris, and the Crocus may be taken as familiar examples. 
The floral envelopes are also called the non-essential organs 
of the flower, because their presence is not absolutely necessary 
for the production of the seed. Sometimes there is only one 
floral envelope, as in the Goosefoot (jig. 29) ; this is then pro- 
perly considered as the calyx, whatever be its colour or other 
peculiarity, and the flower is described as apetalous, or it is 
technically said to be Monochlamydeous. Some botanists, how- 
ever, use the term perianth in this case, as will be described 
c 
