1724 A TEXTBOOK OF THEORETICAL BOTANY 



of secondary importance. His reasons for this are, firstly, that the pollen 

 is not easily dispersed; secondly, that the structure of the filaments of the 

 anthers, the flower stalks, and the inflorescence are firm and rigid, not 

 flexible and supple as in most anemophilous flowers; and thirdly, that the 

 course of anthesis does not agree with that in anemophilous flowers, since 

 the anthers do not dehisce all at once but open over an extended period. 

 The most obvious visitors to these flowers are not, however, the large 

 flying insects normally associated with entomophily, but small bugs, aphids, 

 flies and other creeping or crawling insects. It is possible that there is a 

 slight nectar secretion from the glandular disc or from the papillae which 

 cover this organ in certain genera. Alternatively they may merely enter the 

 flowers to gain protection and to make use of the hiding-places which the 

 flowers readily provide. 



Fig. 15Q9. — Beta nunitiina. Longi- 

 tudinal section of flower. 



Salicorma is probably mainly self-pollinating. Kochia is thought to be 

 pollinated by wind. In Chenopodiiim insects' visits only occur occasionally 

 and self-pollination is usual. In Beta (Fig. 1599) the ovary is surrounded 

 by a nectar-secreting disc and the flowers have been observed to be polli- 

 nated by hover flies. Finally in Atriphx it is uncertain whether wind or 

 insects are the chief agents of pollination. 



Automatic self-pollination is commonly found in the genera Suaeda 

 and Salsola, though the latter is to some extent anemophilous. Included 

 here is Haloxvlon ammodendron which forms a striking feature on the 

 central Asiatic steppes. It has a thick stunted trunk, sometimes reaching 

 as much as 20 ft., which bears tufts of long, whiplike and apparently 

 leafless branches. It is known as the Saxaul. 



Caryophyllaceae (Silenaceae) 



This family shows the highest floral expression of the Centrospermae 

 and contrasts markedly with the Chenopodiaceae. It is well represented in 

 the British Flora and many species are cultivated as ornamental garden 



