122 BOTANY. 
hazel, are called monecious ;1 but there are also plants which have the 
male and female flowers on separate plants, as: the date-palm and the ~ 
hemp, and these are called: diwcious.2 Flowers which have both stamens 
and pistils are called perfect flowers, because all the essential parts of the 
flower are found in them. In some such, however, the calyx or the corolla 
is awanting ; and there are flowers which have none of these envelopes, but 
consist of stamens and pistils only: such flowers are described as naked. 
A flower which has calyx, corolla, stamens, and pistils, is called 
complete. 
The parts of a flower are variously arranged. The leaves of the calyx 
and corolla, the sepals and petals, are sometimes opposite to one another, 
sometimes alternate, and a similar diversity appears in the inner whorls. 
Not unfrequently there are two or more stamens for each petal, and 
sometimes many; and the stamens are sometimes in bundles, as if many 
were formed by the division of a single leaf. Some of the whorls which 
form a flower often consist of a number of parts, which is a multiple of 
the number that characterises the flower, making it trimerous, pentamer- 
ous, &c.—as six instead of three, or ten instead of ‘five. This regularity 
of numerical arrangement is called the symmetry of flowers. A flower in 
which the parts of each whorl are equal and similar, or nearly so, is 
called a regular flower, as the flower of the crocus or primrose. Many 
flowers, however, are irregular. Sometimes one leaf of the calyx is more 
developed than the rest, and assumes a different form; this more 
‘frequently occurs in the corolla, and sometimes in the stamens. The 
flower of a true geranium is regular; but the flower of a pelargonium, 
which is very nearly allied to a geranium, and is often called by that 
name, is irregular, the five petals of the flower appearing as two upper 
and three lower petals, with some difference of size and form. In the 
flowers of many orchids, irregularity may be said to be carried to its 
extreme. Some irregular flowers assume peculiar forms, and some of 
these are Raster of certain orders of plants. Thus, the form called 
papilionaceous,® because of its resemblance to a butterfly , prevails generally 
in an order of plants containing a multitude of species, and producing 
their seeds in pods, of which the pea is an example. 
Fruit—The matured carpels of the flower form the fruit of a plant, and 
the matured ovules the seeds. Sometimes the fruit consists only of a 
single carpel, which contains only one seed, or a number of seeds ; some- 
times of a number of carpels belonging to the same flower, which are 
either separate or closely united together, so as to form one seed-vessel, or 
pericarp. In pines and firs, there is no seed-vessel, but the seeds 
are protected by scales. The fruit is sometimes formed not merely 
1 From Greek monos, one, and oikos, a house. 3 From Latin papilio, a butterfly. 
2 From Greek dis, twice, and otkos, a house. 4 From Greek peri, around, and karpos, fruit. 

