Fig. 423. 



215 



Fig. 421. riower of Wallflower {Cheiranthus Cheiri). c. Calyx composed of 

 parts called sepals, the two lateral of which are prolonged at the base into 

 a little sac, and hence are said to be gibbous. p,p. Petals of which there 

 are four arranged in a cruciform manner, the whole forming the corolla, e. 



Summit of the stamens, which enclose the pistil Fig. A22. Flower of 



Wallflower with the calyx and corolla removed, in order to show the essential 

 organs of reproduction, r. Receptacle or thalamus, gl. Glands, ec. Sta- 

 men, of which there are six, four long and two short, sti. Stigma, the 



summit of the pistil Fig. 42.'5. One of the stamens of the Wallflower. 



/. Filament, a. Anther, p. Pollen. 



ally all coloured or petaloid in their nature. The Tulip, the 

 Iris, and the Crocus, may be taken as familiar examples. 



The floral envelopes are called the non-essential organs of the 

 flower, because their presence is not absolutely necessary for 

 the production of the seed. Sometimes one floral envelope only 

 is present, as in the Goosefoot {Chenopodium) {fig. 425), this 



Fig. 424. 



Fig. 425. 



Fia 424. Flower of a species of Squill (5ei7Za italicaT). The parts composing 

 tlie floral envelopes here closely resemble each other, and form collectively 

 a perianth Fig. ^25. Flower of Goosefoot iChempcxliuni), with only one 



floral envelope. 



P4 



