THE FLOEAL ENVELOPS, OB PERIANTH. 



99 



488. Pekigynium is tbe name given 

 to the urceolate perianth of Carex, in- 

 vesting the ovary but allowing the style 

 to issue at its summit. It is evidently 

 composed of two united sepals. 



489. Glume% and pales represent 

 the floral envelops, or rather the invo- 

 lucre of the Grasses. Their alternating 

 arrangement clearly distingCiishes them 

 from a perianth. They occur in pairs, 

 the smaller usually above. The glumes 

 envelop the spikelet, the pales the single 

 flower, and often within the pales are 

 two or three scales representing the 

 perianth, surrounding the stamens and 

 ovary, all which are illustrated in the 

 wheat. (195.) 



490. The duration of the calyx and corolla varies widely, and is 

 marked by certain general terms. It is caducous when it falls off im- 

 mediately, as the calyx of poppy, corolla of grape ; deciduous when it 

 falk with the stamens, as in most plants ; and persistent if it remain 

 until the fruit ripens, as the calyx of apple. If it continue to grow 

 after flowering, it is accrescent, and if it wither without falling off it is 

 marescent. 



834, Flower of Sctrpus lacaatris, mag- 

 nified ; consisting of six seta), three sta- 

 mens, three pistils united, except the 

 stigmas, 835, Flower of Carex rivularis 

 s , with 17, its glnnio,^, its bottle-shaped 

 perigynium, 2-toothed at top, envelop- 

 ing the triple ovary ; stigmas, three. 



CHAPTER XII. 



OP THE ESSENTIAL ORGANS. 



§ THE STAMENS, OR ANDKCECIUM. 



491. Position. Within the safe inclosure of the floral envelops 

 stand the essential organs— the stamens and pistils, clearly distinguish- 

 able from the perianth by their more slight and delicate forms, and 

 from each other by various marks. In the complete flower the androe- 

 cium next succeeds the corolla in the order of position, being the third 

 set, counting from the calyx. 



492. A PERFECT STAMEN cousists of two parts — ihB filament, corre- 

 sponding -with the petiole of the typical leaf, and the anther, answering 

 to the blade. Within the colls of the anther the pollen is produced, a 

 substance essential to the fertility of the flower. Hence the anther 

 alone is the essential part of the stamen. 



