1-36 



BOTANY. 



[CHAP. iv. 



of the same kind to some extent prevents self-fertilization, 

 and certainly favours cross-fertilization. If a number of 

 plants of the primrose or cowslip are examined it will be 

 found that all the flowers of a given plant have the 

 pistil at the top of the tube of the corolla and the stamens 

 halfway down the tube ; or, on the contrary, the stamens 



Fig. 39. Oxlip (Primula elatior). A dimorphic flower. The left- 

 hand figure represents the long-styled form with the stigma, N, at the 

 top of the corolla-tube, and the stamens, s, halfway down the tube. 

 The right-hand figure shows the short-styled form with the stamens, 

 S, at the top of the tube, and the stigma, n, on a short style halfway 

 down the tube. (Slightly magnified. ) 



are at the top of the tube and the pistil halfway down. 

 Such flowers are termed Heteromorphous, as distinguished 

 from Homomorphous flowers, that have in all cases the 

 stamens and pistil occupying the same relative positions. 

 Heteromorphic flowers that have two forms of flower 

 depending on difference of position of stamens and pistil, 



