

A CHAPTER TO STUDY. 7 
Regular Flowers are those that have the parts of each set, 
the sepals and petals, alike in size and form, (Fic. 23.) Irregu- 
lar Flowers are the reverse of regular. (Fic. 24.) 
-It is sometimes found that only one set of floral leaves is 
present. It is then regarded as the Calyx. Collectively the 
floral envelope, or the protecting organs, is spoken of as the 
Perianth ; but the word is mostly used in cases where the 
calyx and corolla run into each other so that it is difficult to 
distinguish them apart. The lily family have a perianth. 
The Stamens, or Fertilizing Organs, of the plant are 
composed of two parts: the Filament, or stalk, which is use- 
ful to uphold the Anther ; and the Anther, a tiny two-celled 
box which contains the Pollen. The Pollen is the yellow 
fertilizing powder which is the essential product of the 
stamens. (FIG. 25.) 
Exserted Stamens are those that protrude from the 
corolla. 
Included Stamens are those that are within the corolla. 
The Pistil, or Seed-Bearing Organ, is divided into three 
parts: the Ovary, the Style, and the Stigma. (Fic. 26.) 
The Ovary is the lower expanded part of the pistil that 
contains the Ovules, or undeveloped seeds. (Fic. 26.) 
The Style is the slender stalk that usually surmounts the 
ovary. (Fic. 26.) 
The Stigma is the flat or variously formed body that ter- 
minates the style. (Fic. 26.) Unlike the other organs of the 
plant, it is not covered bya thin skin or epidermis. Its surface 
is therefore moist and rough so that it readily receives and 
_ holds the pollen when it is deposited upon its surface. 
Each tiny pollen grain that alights on the stigma sends out 
a minute tube that pierces down through the style until it 
reaches an ovule below, which it quickens into life. This is 
known as the process of Fertilization. The ovules then de- 
velop into Seeds, and the ovary enlarges into the Fruit, or 
Seed Vessel. 
Cross-Fertilization is when the pollen of one flower is 

