PHYSIOLOGICAL DIVISION OF LABOR 319 
After a while new buds appear on the sides of the stem at 
points just above the nodes (Fig. 280), that is to say, in 
the azil' or upper angle between leaf and stem; and these 
buds as they expand become lateral branches, which in turn 
may branch similarly. Finally, some of these buds, instead 
of producing more foliage, develop flowers (Fig. 2171). 
94. The flower and the fruit. In the center of the flower 
(Fig. 21711) we find a pistil 2 containing ovules * within an 
ovary *from the top of which grow five styles * each terminat- 
ing in a stigma. Around the pistil are five stamens,’ each 
producing pollen * within an anther® borne on a slender 
filament.1°  Enveloping the stamens are five petals ' and five 
sepals.12 Pollen falling upon the stigmas, brings about the 
development of the ovules into seeds while the ovary ripens 
into a fruit. Pistils and stamens thus being essential to the 
production of seed are called the essential organs of the flower, 
while the petals and sepals, more or less enveloping them, are 
called the floral envelops or perianth.* 
95. Physiological division of labor. Even such a cursory 
examination as we have made of our typical plant is sufficient 
1 Ax’-il < L. azilla, arm-pit. 
2 Pis’-til < L. pistillum, a pestle, such as apothecaries use for pound- 
ing drugs in a mortar, pistils often resembling pestles more or less in 
form. 
3 O’-vule < L. ovulum, diminutive of ovwm, an egg. 
4 Ov’-ar-y < L. ova, plural of ovum; ary, repository. 
° Style < Gr. stylos, a pillar. 
6 Stig’ma < Gr. stigma, a spot. 
7Sta’men < Gr. stamon, a thread. 
8 Pol’len < L. pollen, fine dust. 
9 An’ther < Gr. anthein, to blossom. 
10 Fil’a-ment < L. filum, thread. 
11 Pet’al < Gr. petalos, outspread. 
12 Sep’al < L. separ, separate, different. 
13 Per’i-anth < Gr. peri, around; anthos, flower. 
stem (caulicle) has just pushed through the seed-coat and is pushing 
the seed-root (radicle) into the ground. C, later stage in which the 
radicle has elongated and produced root-hairs, while the caulicle has 
pushed up the seed. D, still later stage in which the caulicle has become 
further elongated and arched and the seed-leaves or cotyledons are 
growing out of the seed. E, plantlet showing pair of cotyledons ex- 
panded and ready to act like leaves; also three pairs of primary leaves 
and a stem developed from the seed-bud or plumule. F, plantlet still 
older, showing, in addition, secondary leaves, formed one at a joint. 
(Original.) 
