230 



OEGANOGEAPHY. 



growing outwards of one or more of the petals into processes 

 of different kinds. Thus in the Snapdragon {Antirrhinum) {fig. 

 472, b), and Valerian {Valeriana) {fig. 478), the lower part of 

 the tube of the corolla becomes dilated on one side, so as to form 

 a little bag or sac, it is then termed saccate or gibbous ; this term 

 being ^ used in the same sense as previously described when 

 speaking of the calyx. At other times, one or more of the petals, 



Fig. 478 



Fig. 478. Flower of a species of Valerian (Valeriana), c. Calyx, adherent 

 to the ovary. I. Limb of the calyx rolled inwards. The corolla has a 



projection towards its base, and is said to be gibbous. Fig. 479. 



Flower of Red Valerian (Centranthtcs). The corolla is irregularly 



salver-shaped and spurred. Fig. 480. A portion of the flower of the 



Monkshood iAconiticm), with numerous stamens below, and two 

 stalked horn-shaped petals above. 



or the tube of a monopetalous corolla becomes prolonged down- 

 wards, and forms a spur, in which case the corolla or petal 

 is described as sptirred or calcarate. Examples of spurred 

 petals or corollas may be seen in the Heartsease, Columbine, 

 Toadflax {Linaria) {fig. 473), and Ked Valerian {Centranthus) 

 {fig. 479). The Yellow Toadflax, which usually only produces 

 one spur, in rare instances is foimd with five. Such a variety 

 was termed by Linnseus Peloria, a name which is now applied 

 by botanists to all flowers which exhibit this departure from 

 their ordinary growth. In the Monkshood {Aconitum) {fig. 480), 

 the two petals which are situated under the helmet-shaped sepals 

 already noticed {fig. 440), are each shaped somewhat like a curved 

 horn placed on a long channelled stalk. 



The corolla is usually composed of but one whorl of petals, and 

 it is then termed simple, but in some flowers there are two or more 

 whorls, as in the White Water-Lily {fig. 436), in which case it is 

 called multiple. When the corolla is composed of but one whorl. 



