GS EASY LESSONS IN VEGETABLE BIOLOGY. 



The flowers of Exogens exhibit two Or five parts, 

 or multiples of these numbers, in their whorls, while 

 Endogens have three, or a multiple of three, in their 

 whorls. In Exogens, also, the calyx is usually green 

 and the corolla colored, but in Endogens both are often 

 colored. The term perianth is generally applied to 

 the floral envelopes of Endogens. 



The parts of the calyx, when separate, are called 

 sepals, and the leaves of the corolla petals. Stamens 

 have two parts, the filament, or stalk, and the anther, 

 or broader portion, corresponding to a folded leaf, and 

 containing fertilizing grains called pollen. The pistil 

 is also made up of two parts, the ovary, containing 

 ovules, or young seeds, and the stigma for the recep- 

 tion of the pollen-grains. This latter is sometimes 

 sessile, or resting on the ovary, and sometimes ele- 

 vated on a stalk, or style. 



Some flowers have no stamens, and are called fe- 

 male flowers; others have no pistils, and are male 

 flowers. But these organs are always present, either 

 on the same plant or on different plants. If the co- 

 rolla is absent the flower is called incomplete, and if 

 corolla and calyx are both absent it is naked. The 

 position of the stamens in relation to the ovary is of 

 botanical importance. Sometimes they are attached 

 to the receptacle, or upper part of the flower-stalk. 

 They are then below the ovary and free from it, as 

 well as from the calyx, and are said to be hypogynous y 



