216 



ORGANOGRAPHY. 



Fig. 426. Flower of 

 the cominon Asli, 

 in which tlie floral 

 envelopes are al- 

 together absent. 



to be sessile. 



is then properly considered as a calyx, whatever he its colour 

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

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

 At other times, as in the Willow (Salix) and 

 Ash.(Jxg. 426), the floral envelopes are absent, 

 when the flower is termed naked or Achlamy- 

 deous. When both floral envelopes are pre- 

 sent, as in the complete flower above described 

 {fig. 421), it is Dichlamydeous. 



The Stamens constitute the whorl or whorls 

 of organs situated on the inside of the corolla 

 {fig. 422 ec). Each stamen consists essentially 

 of a case or bag, called the Anther {fig. 423, a), 

 which contains in its interior a powdery sub- 

 stance called the Pollen {fig. 423, p) ; this is 

 discharged at certain periods through little 

 slits or holes formed in the anther. These 

 are the only essential parts of a stamen, but it 

 generally possesses in addition, a httle column 

 or stalk, called the Filament {fig. 423, /), 

 which then supports the anther on its summit. 

 When the filament is absent, the anther is said 

 Tlie staminal system, taken collectively, is 

 termed the Andrcecium fi'om its constituting the male system 

 of Flowering Plants, 



The Pistil is the only remaining organ ; it occupies the 

 centre of the flower {fig. 422, sti), all the other organs being 

 arranged around it when these are present. It consists of one 

 or more modified leaves, called Carpels, which are either dis- 

 tinct from each other, as in the Columbine {Aquilegia vidgaris) 

 {fig. 427), or combined into one body, as in the Poppy 

 {fig. 428) and Tobacco {Nicotiana Tabacum) {fig. 568. 2). 

 The carpels taken collectively constitute the Gynoecium or the 

 female system of Flowering Plants. The pistil consists of a 

 hollow inferior part, called the Ovary {fig. 429, d), whicli 

 contains the rudimentary seeds called Ovules o, o ; of a Stigma, 

 or space of variable size, composed of lax cellular tissue with- 

 out epidermis, Avhich is either placed on the ovary, as in the 

 Poppy {fig. 428, sti), or situated on a stalk-like portion pro- 

 longed from the ovary, called the Style {fig. 427, sty). The only 

 essential parts of the pistil are consequently the Ovaiy and Stig- 

 ma ; the style being no more essential to it than the filament is 

 to the stamen. 



The stamens and pistil are called essential organs because 

 their presence is necessary for the production of })orfcct seeds. 

 It frequently happens, liowever, that either the stamens or pistil 

 are absent in a flower, as in the Willow {figs. 392 and 393), in 

 which case it is termed unisexual, and the flower is further 



