i8o 



BOTANY FOR BEGINNERS 



CHAP. 



divided into equal halves in any plane it is said to be asym- 

 metrical, as in a few plants which belong to the Pink family. 



The portion of the flower which faces the bract in the axil or 

 which it stands is called the anterior part ; while the portion 

 which faces the axis of the inflorescence is the posterior part. 

 The plane which passes through the flower in such a way as to 

 divide it into oosterior and anterior halves is called the trans- 

 verse one, and that which 

 passes through the middle 

 of the bract and axis of 

 the inflorescence is said 

 to be the median plane. 



EXPT. 1 66. Obtain a 

 flower of the Gorse or 

 Laburnum and examine it. 

 Note 



(i) The large petal which 

 receives the name of the 

 standard is posterior, be- 

 cause it is the nearest to the 

 axis of the inflorescence. 



(ii) The two petals which 

 slightly adhere, and are 

 called the keel, are anterior, 

 because they are the nearest 

 to the bracts. 



(iii) The two petals, one 

 on each side of the stan- 

 dard, receive the name of 

 wings ; they are lateral, i.e., 

 at the sides. 



(iv) The flower is irregu- 

 lar, or zygomorphic, because 



there is only one plane along which a section can be made to divide 

 it into equal halves. This plane passes through the centre of the 

 standard and between the petals of the keel. 



EXPT. 167. If the flower of the Apple or Blackberry can be ob- 

 tained, examine it. Note 



(i) The flower consists of five sepals and five petals, 

 (ii) It can be divided into equal halves in any plane, therefore 

 it is regular or actinomorphic. 



Shape of Flower. There are a number of terms which are 

 used in describing the shape of the flower. It is said to be 



I. Cruciform, when the petals are arranged in the form of a 

 cross, as in the Wallflower and Cabbage. (Fig. 185). 



FIG. 184. A, Raceme of Laburnum ; st, stan- 

 dard ; w, wings; k, keel, i, 2, 3, the 

 flower from different points of view. 





