64 
COKOLLA. 
cately shaded, and blended ; in others, they meet abruptly, without any interme 
diate tint. The color of the corolla, in the same species, often varies without any 
assignable cause. This fact is strikingly illustrated in the four o'clock (Mirabilis) ; 
the flowers of which are sometimes of pale yellow, sometimes bright crimson, and 
often richly variegated. The florist watches these changes, and, as far as possible, 
avails Mmself of them in the production of new beauties in the vegetable kingdom. 
The corolla before blossoming is folded in the calyx, as the leaves are within the 
scales of the leaf-bud. In most cases, the calyx and corolla are distinctly marked 
The color usually constitutes a striking mark of difference ; the calyx being ordi- 
narily green, and the corolla of a more lively hue. But the color is not always a 
criterion, for in some cases the calyx is beautifully colored. In the Fuschia 
{Ladys ear-drop), the calyx is of a bright scarlet ; we might at first think it to bo 
the corolla ; but on removuig the scarlet coat we see, wrapped around the eight 
stamens, a purple covering ; on taking off each piece carefully, we find four petals, 
as distinct as the petals of a rose. 
71. The parts of the corolla or petals, according to normal 
arrangement, alternate with the sepals, and either equal them, 
or are some multij^le of their number. But this symmetrical 
arrangement of nature is often broken up, by peculiar circum 
stances attending the growth, as in chorisis or dedoublement^ 
which terms signify unhning^ meaning that the organ in question 
unlines or separates into two or more layers, each having the 
same structure, and thus increasing the normal numher oi 
organs. When the corolla falls off soon after flowering, as in 
the poppy, it is said to be caducous / when it fades and with 
ers upon the stalk, as in the blue-bell, it is then said to bo 
marescent. A flower without petals is said to be ajpetalous. 
Petals are said to be definite when their number is not more 
than twenty ; indefinite^ when they exceed that number. The 
parts into which a corolla naturally falls, may be considered as 
so many petals. Tlie name polyiMalous is given to corollas 
liaving separate petals, while m.onojpetalous is applied to those 
which appear to have but one petal ; but, as it is now admitted 
that all corollas are formed of several united petals, the term 
gamopetalous (from gamos^ union), or imited petals, is often 
used ; yet, as the term monopetalous has been incorporated intc 
the science of botany, it continues in use. The union of petals 
generally takes place at the base, and extends more or less 
toward the apex. Monopetalous corollas (or when the petals 
unite so as to form but one piece) consist of the tube^ throaty 
and limb. The tube is the lower part : the throat the entrance 
into the tube ; it is either open, or closed by scales or hairs. 
The lamina or limb is the upper border of the corolla. In Poly- 
petalous corollas^ each petal consists of two parts, the lamina 
and claio. Petals, properly so called, belong to Exogenous 
plants, for in the Endogenous, the flower consists of a perianth, 
which is considered as a calycine envelope. The venation oi 
petals resembles that of the leaves of Exogenous plants ; the 
Its situation before expanding — How distinguished fvovc tlie calvx I — 71. Normal arra.no'e^ent oi 
letals — Duration — Parts of ilie corolla — Forms ol' aionopetalous corolla. 
