OUTLINES OF BOTANY. 
xiii 
90. Such a complete symmetrical flower consists usually of either four or five whorls 
of altered leaves (88), placed immediately one within the other. 
The Calyx forms the outer whorl. Its parts are called sepals. 
The Corolla forms the next whorl. Its parts, called -petals , usually alternate with 
the sepals ; that is to say, the centre of each petal is immediately over or within the 
interval between two sepals. 
The Stamens form one or two whorls within the petals. If two, those of the outer 
whorl (the outer stamens ) alternate with the petals, and are consequently opposite to, 
or over the centre of the sepals ; those of the inner whorl (the inner stamens) alternate 
with the outer ones, and are therefore opposite to the petals. If there is only one 
whorl of stamens, they most frequently alternate with the petals ; but sometimes they 
are opposite the petals and alternate with the sepals. 
The Pistil forms the inner whorl ; its carpels usually alternate with the inner row 
of stamens. 
91. In an axillary or lateral flower the upper parts of each whorl (sepals, petals, 
stamens, or carpels) are those which are next to the main axis of the stems or branch, 
the lower part3 those which are furthest from it ; the intermediate ones are said to be 
lateral. The words anterior (front) and posterior (back) are often used for lower and 
upper respectively, but their meaning is sometimes reversed if the writer supposes 
himself in the centre of the flower instead of outside of it. 
92. The number of parts in each whorl of a flower is expressed adjectively by the 
following numerals derived from the Greek 
mono-, di-, tri-, tetra-, penta-, hexa-, hepta, octo-, ennea-, deca-, etc., poly- 
I-, 2-, 3-, 5-, 6-, 7-, 8-, 9-, 10-, many - 
prefixed to a termination indicating the whorl referred to. 
93. Thus, a Flower is 
disepalous, trisepalous, tetrasepalous, polysepalous, etc., according as there are 
2, 3, 4, or many (or an indefinite number of) sepals. 
dipetalous, tripetalous, polypetalous, etc., according as there are 2, 3, or many 
petals. 
diandrous, tnandrous, polyandrous, etc., according as there are 2, 8, or many 
stamens. 
digynous, trigynous, polygynous, etc., according as there are 2, 3, or many carpels. 
And generally (if symmetrical), dimerous , trimerous, polymerous, etc., according 
as there are 2, 3, or many (or an indefinite number of) parts to each whorl. 
94. Flowers are unsymmetrical or anisomerous, strictly speaking, when any one of 
the whorls has a different number of parts from any other ; but when the pistils alone 
are reduced in number, the flower is still frequently called symmetrical or isomerous, 
if the calyx, corolla, and staminal whorls have all the same number of parts. 
95. Flowers are irregular when the parts of any one of the whorls are unequal in 
size, dissimilar in shape, or do not spread regularly round the axis at equal distances. 
It is however more especially irregularity of the corolla that is referred to in descrip- 
tions. A slight inequality in size or direction in the other whorls does not prevent the 
flower being classed as regular , if the corolla or perianth is conspicuous and regular. 
§ 9. The Calyx and Corolla , or Perianth. 
96. The Calyx (90) is usually green, and smaller than the corolla ; sometimes very, 
minute, rudimentary, or wanting, sometimes very indistinctly wliorled, or not whorled 
at all, or in two whorls, or composed of a large number of sepals, of which the outer 
ones pass gradually into bracts, and the inner ones into petals. 
97. The. Corolla (90) is usually coloured, and of a more delicate texture than the 
calyx, and, in popular language, is often more specially meant by the flower. Its petals 
are more rarely in two whorls, or indefinite in number, and the whorl more rarely 
broken than in the case of the calyx, at least when the plant is in a natural state. 
Double flowers are in most cases an accidental deformity or monster in which the ordi- 
nary number of petals is multiplied by the conversion of stamens, sepals, or even carpels 
into petals, by the division of ordinary petals, or simply by the addition of supernume- 
rary ones. Petals are also sometimes very small, rudimentary, or entirely deficient. 
