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tics which are present in summer from those which are present in 

 winter, it has sometimes been found necessary to make two keys to 

 the species, one a summer key and the other a winter key. Two such 

 keys are found under the Maple family. If the material at hand hap- 

 pens to be a spray of leaves of the Sugar Maple, the summer key 

 should be used, and if it happens to be a branchlet with buds, the 

 winter key should be used. 



Since the family key which was used to this point was based pri- 

 marily upon summer characteristics, the winter key will now be used 

 in order to familiarize you with the slight variations which are found 

 between the two keys. Under "Winter Key to the Species," page 191, 

 we start with 1. Under 1 we have the choice between "Buds stalked 

 with few exposed scales" and "Buds sessile or nearly so, with 6 or 

 more exposed scales." We select the latter, which is followed by 4. Un- 

 der 4 we have the choice between "Buds with 8-16 exposed scales, 

 brown, acute, non-collateral; leaf-scars nearly encircle stem" and 

 "Buds with 6-8 exposed scales, red or green, obtuse." We select the 

 former which is followed by Sugar Maple (Acer saccharum) page 194. 

 On this page a full description of the species js found accompanied 

 by a sketch on the opposite page of the principal characteristics. 

 If the descriptive material and the sketches show that this is the 

 species under consideration, one may feel satisfied that the key has 

 been used properly. If the description does not correspond it is 

 advisable to go back to the beginning of the key, follow the same pro- 

 cedure indicated above but eliminating the mistake which must have 

 been made. The same method of identification or procedure should 

 be used for every other species. In a short time one will be familiar 

 enough with the use of the key to identify the species and will do so 

 with considerable accuracy. 



If you cannot identify the specimen at hand with the aid of the 

 keys, description, and plates, there are still other means which you 

 may use: It may be possible that an institution or a private person 

 in your part of the State possesses an herbarium in which may be 

 found a similar specimen properly labeled. If you can get access to 

 such an herbarium and find that your specimen and the one in the 

 herbarium are alike, and that the herbarium specimen was labeled 

 by a reliable person, it is reasonable to assume that you have identi- 

 fied your specimen correctly. It may also be possible that some one 

 connected with some local educational institution will be able to as- 

 sist you in identifying the material. All material sent to the Den- 

 drological Department of the Pennsylvania State Forest Academy, 

 Mont Alto, Pa., will be identified free of charge. Persons sending 

 material should always aim to send an abundance of it. If flow- 

 ers, leaves, fruits, and bark are obtainable they should all be sent. 



