ACER. 



191 



sterile ( $ ), the stamens are prominently exserted and the 

 stigmas deficient ; in the fertile ( $ ), the stamens are defi- 

 cient and hidden in the calyx, and the 2 stigmas prominent, 

 with a double ovary. 



The Fruit. As the ovary matures, a wing grows on the 

 back of each carpel, converting the fruit into 2 winged 

 samaras, or a double samara (a key), separable into two 

 single ones. In each there is one seed, containing an embryo 



11 



6, section of a samara, showing the folded cotyledons at e ; 7 to 11, progressive 

 stages of germination. 



with 2 large, folded cotyledons, and no albumen. It is in- 

 structive to watch the progress of these seeds in germination, 

 as may be seen in all stages, in living specimens, under the 

 Maples in Spring, as represented in the cuts. 



The Sap of the Rock Maple is rich in sweetness, contain- 

 ing about 1 part of sugar to 30 parts of water. Early in 

 March, or in February, while the buds are yet dormant, the 

 sap begins to arise from the roots, and will overflow through 

 tubes inserted in auger-holes cut deep into the wood for this 



