256 



STRUCTURE AND VITAL PROCESSES OF PLANTS 



The calyx may also be spurred, and then it is often coloured, 

 as in the Balsam. 



We tind the same conditions in the corolla. The flowers of 

 the Lotus, the Mustard, the Shoeflower, the Rose, the Poinciana 



are choripetalous. Their petals 

 have always more or less long 

 stalks, called claws. Gamopetalous 

 are the flowers of Ixora, Vinca, 

 Tobacco, Argyreia, and Tulasi. 

 Their crowns assume many shapes, 

 as of a tube (the tubular disc- 

 flowers of the Sunflower), or of a 

 funnel (Bindweeds), or of a bell 

 (Allamanda), or of a mouth with 

 two lips (Labiata', Acanthaceie). 

 Choripetalous and zygomorphic 

 are the butterfly-shaped flowers of 

 the Papilionacea', gamopetalous 

 and zygomorphic those of the Labiata\ The flowers of the 

 ConvolvulacCce are gamopetalous and radial, those of the Malva- 

 ceae are choripetalous and radial. The two whorls of a perianth 

 may combine and form one tube, as in Crinum and Eucharis Lily. 

 In order to protect etticiently the inner essential organs, the 

 sepals and petals do, as a rule, alternate, one with the other so 

 that the gap between two sepals is closed by a petal, and in- 

 versely. In 

 bud, moreover. 



cA K. 



Fig. 237. — Flower of Pea dissected 

 into its various parts: St. Standard. 

 W. Win<?s. K. Keel. C. Calyx 

 of whicli the front part is removed. 



)usly 

 raniied. 



o 



The 



mode of their 7 



^ 



arrangement 



yl'^stivation of petals. 



Z 



Fig. 238.- 



in relation to 



one another is called (rstiratiou. This may be valvate (sei)als 

 of Shoeflower), or imbricate = overlapi)ing (Poinciana, Rose), or 

 contorted = twisted (Periwinkle), or i)licate = folded (Argyreia). 



