256 



BOTANY OF THE LIVING PLANT 



functions are to receive the pollen, and to enclose and protect 

 the Ovules. (Fig. 177, ov.) Under favourable conditions each ovule 

 is able to produce a single new germ, and to develop into a mature 



Seed. 



The relations of these floral parts to the receptacle are similar to 

 those of the foliage leaves to the stem ; for they arise laterally upon 

 it, and their succession is such that the oldest are the lowest, or outer- 

 most, and the youngest the inner- 

 most, or nearest to the tip. No 

 buds are produced in their axils. 

 As in the foliage shoot the appen- 

 dages may be arranged spirally, 

 or in whorls, but in the flower the 

 latter is the more common. The 

 members of the successive whorls 

 usually alternate with one another. 

 This is convenient for their close 

 packing in the bud. The, parts of 

 the flower are as a rule closely 

 aggregated together, while those of 

 the vegetative shoot may be separ- 

 ated by long internodes. But all 



Fig. 178. J is 



(i) single male flower of Spurge (Enphor- normal leafy shoots terminate in a 



bia), consisting of one stamen, with abortive 111 1 , 1 



perianth, (ii) Single female flower, consisting bud, and SO, at least in the young 

 of three carpels, and an abortive perianth. ,1 1-1 a.w~ „1„~ 



(iii) Single male flower of Anthostema State, the tWO are alike in thlS alSO. 



up or laceae). There are thus marked analogies 



between the foliage shoot and the flower. Both are constructed on the 

 same plan. There is, however, one absolutely distinctive character which 

 separates them. It is the presence in the Flower of the Organs of 

 Propagation, called Sporangia. These have no correlative in the 

 vegetative region. They are organs of a separate category altogether. 

 Accordingly the Flower may be defined as a simple Shoot which bears 

 Sporangia. 



In the Flowering Plants the Sporangia are of two sorts, viz. Pollen- 

 Sacs and Ovules. In very many cases these are both present in the 

 same flower, which is then called Hermaphrodite. But in others only 

 one or the other is present. When the flower contains stamens 

 bearing pollen-sacs, but no carpels, it is described as Staminate ; when 

 it has carpels bearing ovules, but no stamens, it is called Pistillate. 

 The biological importance of these differences of distribution is great, 

 as they are closely related to the mechanism of intercrossing. 



in 



