28o 



DICO T YLED ONS. 



Topic VU: Dicotyledons with distinct petals and 

 epigynous flowers. 



MYRTIFLOR^. 



536. Lesson XV. The evening-primrose family (onogra- 

 ceae). — In the evening primrose (cenothera) the flowers are ar- 

 ranged in a loose spike along 

 the end of the stem, each one 

 situated in the axil of a leaf- 

 like bract. The flowers of the 

 family are very characteristic, as 

 shown here. They are sessile 

 in the axil of the bract, and the 

 calyx forms a long tube by the 

 union of the sepals, only the end 

 of the tube being divided into 

 the individual parts, showing 

 four lobes. On the edge of the 

 open end of the calyx tube are 

 seated the four, somewhat heart- 

 shaped, yellowish petals, and 

 here are also seated the eight 

 stamens. The four carpels are 

 united into a single pistil within 

 the base of the calyx tube and 

 united with it, so that the calyx 

 tube seems to be on the end of 

 the pistil. The flowers soon 

 fade and fall away from the pistil, 

 and this grows into an elongated 

 four-angled pod. Since the 

 lower flowers on the stem are the older, we find nearly mature 

 fruit and fresh flowers, with all intermediate grades, on the 

 same plant. 



The plants grow by roadsides and in old fields. They are from 

 \ocm to a meter or more high (one to five feet). The leaves are 



Fig. 371. 

 Section of flower 

 of Qlno^hera. 



