250 



Minnesota Plant Life. 



inclosed within, or standing in a cup composed of numerous 

 bractlets ordinarily grown together and woody. In some oaks 

 the fruit matures within a year, but in other varieties a longer 

 time is required. Oaks are employed for a variety of purposes 

 — as firewood, in the manufacture of timbers in which great 

 durability is demanded, and as plants from which tan-bark may 

 be procured. The acorns are eaten by domestic animals, and 

 the various species are prized as shade-trees. 



I'iG. llti. waks and blue flags, A mari^liy place in the oak-woods. After photograph by 



Williams. 



The different \arieties in Minnesota may be thus distin- 

 guished : Of those forms in which it takes the acorn two years 

 to mature, the red oak has leaves green on both sides and the 

 acorn cup much broader than high, while in the scarlet oak the 

 cujj of the acorn is about as high as broad, the leaves are smooth 

 on each side, and the inner bark gray. In the black oak, which 

 is much like the scarlet oak in appearance, the leaves on the 

 under side develop a few hairs where the veins branch, and the 

 inner bark is orange in color. In all three species which have 

 been mentioned the acorns do not mature until the aiUumn of 



