266 



DICOTYLEDONS. 



flowers have four small sepals and four stamens. The fertile flowers (pistil- 

 late) have also four sepals. The pistil has a two-loculed ovary; one of the 

 locules is the smaller, and later disappears, so that the fruit is a one-seeded 

 achene. The parts of the flower are in twos, since the four sepals are in two 

 pairs. 



515. Lesson VI. The elm family (ulmaceae). The elm tree 

 belongs to this family. The leaves of our American elm (Ulmus 

 americana) are ovate, pointed, deeply serrate, and with an ob- 

 lique base as shown in fig. 347. The narrow stipules which are 



Fig- 347- 



Spray of leaves and flowers of the American elm ; at the left above is section of flower, 

 next is winged seed (a samara). 



present when the leaves first come from the bud soon fall away. 

 The flowers are in lateral clusters, which arise from the axils of 

 the leaves, and appear in the spring before the leaves. They 

 hang by long pedicels, and the petals are absent. The calyx is 

 bell-shaped, and 4-9-cleft on the margin. The stamens vary also 

 in number in about the same proportion. A section of the 

 flower in fig. 347 shows the arrangement of the parts, the ovary 

 in the center. The ovary has either one or two locules, and two 

 styles. The mature fruit has one locule, and is margined with 

 two winged expansions as shown in the figure. This kind of 

 a seed is a samara. 



