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 axil ' 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. 217II) we find a pistil - containing ovules ' within an 

 ovary ' from the top of which grow live styles * each terminat- 

 ing in a stigma.'' Around the pistil are five stamens,'' each 

 producing pollen ' within an anther ' borne on a slender 

 filament.^" Enveloping the stamens are five petals " and five 

 sepals.'-- Pollen falling upon the stigmas, brings about the 

 development of the ovules into seeds while the ovarj- ripens 

 into a fruit. Pistils and stamens thus being essential to the 

 production of seed are called the es.seiitial organs of the floiver, 

 while the petals and sepals, more or less enveloping them, are 

 called thv fl(n-al envelops or perianth.'^ 



95. Physiological division of labor. Even such a cursory 

 examination as we have made of our typical plant is sufficient 



' Ax'-il < L. axilla, arm-pit. 



- Pis'-til < L. pistillum, a pestle, such as apothecaries use for pound- 

 ing drugs in a mortar, pistils often resembling jiestles more or less in 

 form. 



* O'-vulc < L. ovulum, diminutive of ovum, an egg. 



^ Ov'-ar-y < L. ova, plural of ovum; ary, repository. 

 ■' Style < Gr. stylos, a pillar. 

 ° Stig'ma < Gr. stigma, a spot. 

 ' Sta'men < Gr. stamon, a thread. 



* Pol'len < L. pollen, fine dust. 



' An'ther < Gr. ardtiein, to blossom. 



" Fil'a-ment < L. filum, thread. 



" Pet'al < Gr. petalos, out.spread. 



'^ Sep'al < L. separ, separate, different. 



13 Per'i-anth < Gr. peri, around; anttios, flower. 



stem (caulicle) has just pushed through the seed-coat and is pu.shing 

 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.) 



