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the wings of its keys. In botanical terms, a key is a 

 winged fruit. 



Just before you came to this sugar maple you 

 passed on your left, about midway between the 

 ginkgo tree and the sugar maple, a good specimen 

 of the sour gum or pepperidge or tupelo, as it is often 

 called. I never get tired of singing the praises of 

 these sour gum trees. They are like crusts of bread 

 to the lenses of the eye, when winter has whipped off 

 their leaves and shows them forth in all their gnarled 

 and twisted beauty. What a fire slumbers in their 

 glossy leaves ! The sour gum flowers in April or 

 May, in dense clusters, and its fruit, eggshaped, is 

 bluish black, clustered two or three together on long 

 stems from the axils of the leaves. This tree's leaf 

 has its margin entire, but often beyond the middle 

 strongly angulated. The leaf is thick and shining 

 on the upper side, with a rich gloss. You can pick 

 the tree out at once by its trick of growing its leaves 

 in crowded clusters near the ends of the branches. 

 In autumn no tree in the Park puts on such rich, 

 lustrous, brilliant tones of crimson, maroon, and sub- 

 dued mahogany. 



Beyond the sugar maple, as you go westward along 

 this Walk, you pass on the right, about opposite the 

 Thatched Shelter, an American basswood. Have you 

 noticed the distinct yellowish cast in the green of the 

 American basswood? It is especially distinct in late 

 July or August, and is a sure mark of the tree. 



Further along on your left, you pass a clump of 

 many interesting things, gathered close together in 



