THE AMERICAN BOTANIST 121 



Common Names. — The only thing certain about common 

 names, is that a plant has a common name when it is commonly 

 called by that name in any part of the world. This reflection 

 is induced by a note in a British contemporary protesting 

 against the use of thorn-apple as a common name for the fruits 

 of our species of hawthorn or Crataegus. "Considering its 

 long accustomed use for Datura" says the writer, "this must 

 cause confusion." Here in America the case is just the other 

 way about. Confusion would exist if our common Jimson 

 weed were called thornapple. Considering the case strictly on 

 its merits, the hawthorn fruits have much the best right to be 

 called thornapples for they are certainly little apples and they 

 are borne on thorn trees. Nevertheless we shall have to let it go 

 at that, for both plants are commonly called thornapple in dif- 

 ferent parts of the world and thus both are entitled to the 

 name. 



Growth of Trees. — Considerable uncertainty exists as 

 to the time necessary to grow merchantable timber, but only 

 upon an exact knowledge of such things can a satisfactory 

 policy of forest management be based. According to a writer 

 in Forest Leaves the time required for various kinds of trees 

 to reach a diameter of twelve inches is as follows: pin oak 

 40 years, black oak 50 years, red oak 58, white oak 100, sweet 

 gum 63, walnut 56, tulip tree 50, black locust 45, ash 73, 

 hickory 90, catalpa 30, Carolina poplar 13. Of course the 

 character of the soil, water supply and location have much to 

 do with the slow or rapid growth of trees, but these figures 

 seem fair averages. As to the time required for greater di- 

 ameters the same writer gives records of actual counts for var- 

 ious trees, some of which are added here : Hackberry 35 inches, 

 115 years; elm 37 inches, 130 years; sugar maple 38 inches, 

 155 years; sycamore 57 inches, 360 years; tulip tree 57 inches, 

 335 years; sour gum 35 inches, 141 years; beech 36 inches, 

 165 years; black willow 18 inches, 50 years. 



