XV 
what altered in form and colour; the stamens are leaves, of which 
the petioles are represented by the filaments, while the expanded 
portion, being turned inwards upon the midrib, becomes the anther; 
the carpels of the pistil are likewise leaves variously modified. This 
interesting fact, long since surmised by Goethe, has been long veri¬ 
fied by accui’ate observation; and some of its results are of import¬ 
ance even to the non-scientific observer of flowers. Occasionally 
portions of the corolla are found developed as green leaves,—a mon¬ 
strosity frequently occurring in the garden Tulip. The flowers 
called double are produced by a similar metamorphosis, the leaves 
that are usually developed as stamens and pistils assuming the 
petaloid form; hence perfectly double flowers are incapable of 
maturing seed. 
The duration of plants is variable in different species; but the 
general process of growth is the same in all. The seed, lying upon 
the ground, germinates under the influence of heat and moisture; 
the radicle is elongated, and, penetrating the soil, pushes forth fibres 
which draw up nutriment for the support of the growing plant; 
the plumule rises, bearing with it the cotyledons, which acquire the 
green colour of leaves, and are soon succeeded by the true leaves. 
At some period of its growth the leaves are developed in forms 
more or less modified, and become no longer organs of respir¬ 
ation and transpiration, but assume the characters of floral en¬ 
velopes and of stamens and pistils, through the mutual action of 
which the seed is produced. 
Some plants spring up from the seed and bear flowers and fruit 
within a single season, dying when the process is completed—or are 
annual. Others produce no flowers the first year, but store up 
during that period of growth the nutriment which is absorbed in 
the production of seed in the following summer, when they die; 
these are called biennial. When the plant survives for an indefinite 
period it becomes perermial , either throwing up stems from the 
root each year, which die down after bearing flowers, or producing a 
