192 



FLORAL ENVELOPES. 



Fig. 283. 



of arrangement. Again, in Scilla itdica, the parts are arranged in 

 sets of three in place of five, as shown in fig. 283, where 2)' jj'^ are 

 three parts of the external whorl ; p" p" p", three of the next whorl; e', 

 an outer row of stamens ; e", an inner row ; o, the pistil formed of 

 three parts. It is distinctly seen in these instances that the parts of 

 the flower are to be regarded as leaves arranged on a depressed or 

 shortened axis. 



When all the parts of the flower are separate, and normally de- 

 veloped, there is no difficulty in tracing this arrangement; but ia 

 many cases it is by no means an easy 

 matter to do so, on account of chapges 

 produced by the union of one part to 

 another, by degeneration, by th^ abortion 

 or non-development of some portions, 

 and by the multiplication or folding of 

 others. Of the four whorls noticed, the 

 two outer (calyx and corolla) are called 

 floral envelopes ; the two inner (stamens 

 and pistil) are called essential organs. 

 When both calyx and corolla are present, 

 the plants are Dichlamydeous (its, twice, 

 and yXa/i.iii, a covering) ; occasionally 

 one or both become abortive, and then the flower is either Mono- 

 chlamydeous (/i6vog, single), having a calyx only, or Achlamydeous (a, 

 privative) or naked, having only 



the essential organs, and no DCX «<■ ^-r'/fT" 



floral envelope. pec M\\\ v., //// 



The Floeal Envelopes 

 consist of the calyx and corolla. 

 In most cases, especially in Di- 

 cotyledons, these two whorls 

 are easily distinguishable, the 

 first being external and green, 

 the latter internal, and more or 

 less highly coloured. If there 

 is only one whorl, then, what- 

 ever its colour or degree of de- 

 velopment, it is the calyx. Some- 

 times, as in many Monocotyledons, the calyx and corolla both display 



Fig. 283. Flower of Scilla italioa. p'p'p'. Three external leaflets, or divisions of the 

 Perianth or Perigone. p" p" p". The three internal leaflets, if. Stamens, opposite to the 

 flrst or external leaflets, e". Stamens, opposite the second or internal leaflets, o, Ovaries 

 united together into one. s. Three styles, consolidated so as to form one. Fig. 28t 

 Flower of White Lily {Liliim, dtlyum). p, Perianth or Perigone, having three parts exterior, 

 pe, alternating with three interior, pi. e. Stamens, having versatile anthers attached to the 

 top of the filaments, s, Stigma at the apex of the style. 



Fig. 284. 



