462 



THE MYRTALES 



and placed opposite the sepals, whereas they alternate with the 

 sepals in the Sapindales (Fig. 331, E-G), and the nectary is 

 within the filaments. 



147. Myrtales, the Myrtle Order. — This order marks a decided 

 advance in the evolution of the flower over preceding groups, 

 owing to the mass growth of the calyx and receptacle and usually 

 of the ovary, the flowers being perigynous and usually epigynous. 

 Another important character is that the flowers are always cyclic, 

 the organs being regularly arranged in five whorls of four or less 



Fig. 322. Lower form of the Myrtales, flower perigynous: A, flower of 

 Lythrum. B, flower in section — c, lobe of the tubular calyx, from the margin 

 of which arise the petals, p. This flower has the long form of style and the 

 short and medium form of stamens. C, flower with medium style and with 

 short and long stamens. D, flower with short style and with medium and 

 long stamens. 



commonly of five members each, though the number of stamens 

 may be greatly increased by the splitting of the original number 

 of the set. The petals are frequently suppressed and the calyx 

 is often highly colored, a variation to be seen in many groups when 

 the corolla is wanting. The carpels, as a rule, contain numerous 

 ovules (Figs. 322, 323). The Myrtales is an important tropical 

 order and represented with us by many familiar plants, such as 

 the meadow beauty (Rhexia). willow-herb (Epilobium) , the large 



