208 ORGANOGRAPHY. 



which the parts of the flower are placed, is called the Thalamus 

 or sometimes, but improperly, the Receptacle {fig. 420, r). The 

 floral whorls are situated on the thalamus, proceeding from with- 

 out inwards in the following order: — 1. Calyx, 2. Corolla, 

 3. Androecium, 4. Gryncecium. 



The Calyx {fig. 419, c) is the whorl of organs forming the 

 outer envelope or covering of the flower. Its parts are called 

 Sepals, and these are generally green, and of a less delicate tex- 

 ture than those constituting the corolla. In texture, appearance, 

 &c., they bear commonly a great resemblance to the true leaves. 



The Corolla {fig. 419, jt), jp) is the whorl or whorls of leafy 

 organs situated within the calyx, and forming the inner en- 

 velope of the flower. Its parts, which are called Petals, are 

 frequently decorated with the richest colours; by which cha- 

 racter, and by their more delicate nature, they may be usually 

 known from those of the calyx. 



The calyx and corolla are sometimes spoken of collectively 

 under the name of Perianth or Perigone { fig. 422). This term 

 is more particularly applied to Monocotyledonous Plants, where 

 the floral envelopes generally resemble each other, and are usu- 

 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 also 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. 423); 

 this is then properly considered as a calyx, whatever be its colour 

 or other peculiarity, and the flower is said to be Monochlamydeous. 

 Some botanists, however, use the term perianth in this case. 



„. At other times, as in the Willow {Salix) {figs. 



tig. 424. ggg ^^^ 390^^ ^^^ ^^^^ ^^^^ 424), the floral 



envelopes are absent, when the flower is termed 

 naked or Achlamydeous. When both floral en- 

 velopes are present, {fi^, 419), the flower is said 

 to be Dichlamydeotis. 



The andrcucium constitutes the whorl or whorls 

 of organs situated on the inside of the corolla 

 {fig. 420, ec, ec). Its parts are called stamens. 

 Each stamen consists essentially of a case or 

 bag, called the Anther {fig. 421, a), which con- 

 tains in its interior a powdery substance called 

 the Pollen {fig. 421, p) ; this is discharged, 

 as represented in the figure, at certain periods, 



,„, ^, through little slits or holes formed in the anther. 



Fig. 424. Flower mu i.u i *.• i ^ i? i. 



of tiie common These are the only essential parts oi a stamen, 



floral "^'''*'iTes ^^^ '^^ generally possesses in addition a little 

 are altogether ab- Stalk, Called the Filament {fig. 421, /), which 

 ^^"''- then supports the anther on its summit. When 



