422 



TRANSITION ORDERS 



These characters also appear in the allied goosefoot order, Cheno- 

 podiales, with its great array of common weeds, as the goosefoot 

 {Cheno podium) , orache (Atriplex), tumbleweed and pigweed 

 {Amaranthus) . The flowers are arranged in loose clusters and 

 are for the most part small and anemophilous (Fig. 303). How- 

 ever, it is noteworthy that some of the genera are entomophilous, 



Fig. 304. Advanced type of the Chenopodiales: A, shoot of Melandry- 

 num bearing flower with perianth differentiated into calyx, ca, and corolla, 

 c. B, section of flower, showing the relation of calyx to corolla and the con- 

 cealment of the nectar glands at the base of the ovary. Access to the 

 corolla tube is guarded by an outgrowth on the petals, as shown in C, which, 

 assisted by the styles or stamens, so effectually closes the mouth of the tube 

 that only insects with long tongues can reach the honey. 



the calyx becoming larger and brightly colored and nectar glands 

 are associated with it. In the higher members of the order, as 

 in the purslane and pink families (which include the spring 

 beauty, Claytonia) , the perianth becomes differentiated into a 

 calyx and showy corolla, and the flowers have become in a 

 marked degree adapted to insect visitors (Fig. 304). These 

 orders form a natural transition from the primitive flowers of 

 the willows and beeches to the large flowers of the next order 

 with their showy perianths, though the structure of the flower 

 does not indicate a relationship between them. 



