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SMOOTH ALDER. 

 Alnus rugosa, (Du Roi) Sprengel. 



tENUS description — The Alders comprise about 25 known species, of which number 

 oot 10 species ari native to North America and 2 species to Pennsylvania. The members 

 this genus are distributed widely in the northern hemisphere and extend south through 

 ntral America and along the Andes mountains to Bolivia. Most of them are shrubs or small 

 tea, while a few attain a fair tree-size. 



rOBM — A small shrub usually from 4-10 ft. in height. Sometimes solitary, usually in clumps, 

 ;en forming thickets which are almost impenetrable, especially in wet locations. 



3ABK — Thin, smooth, fluted, astringent, at first brownish-green, later grayish-green, and 

 ;en covered with white blotches. 



CWIGS — Rather slender, at first greenish, later greenish-brown and finally grayish-brown, 

 ten grayish-white towards end of fruiting twigs. Lenticels numerous, scattered, brownish, 

 mdish or longitudinally-elongated. Pith gieenish and irregular or triangular, 



BUDS — Alternate, evidently-stalked, about 1 of an inch long; greenish-red, laterally com- 

 ;ssed, blunt-pointed, apparently covered with two valvate scales which in reality are 

 pules. Stipular buJ-ecales are often whitish towards apex and usually slightly sticky. 



:.EAVES — Alternate, simple, obovate, blunt-pointed or rounded at apex, usually wedge- 

 iped at base, almost regularly serrate on margin at first slightly gummy, later smooth, 

 ber thick, 2i-4i inches long; green on both surfaces, but darker on upper surface, brownish 

 K.soent below especially in the axils of the veins. Veins depressed above and ridged 

 low. 



jEAF-SCARS — Alternate, raised, usually 2 or 3-ranked, somewhat triangular, containing 

 out 3 bundle-scars which are often compounded. Stipule scars narrow, triangular, brownish 

 d very close to leaf scars. 



nOWERS — Appear in March or April before the leaves. Staminate and pistillate occur 

 mrately but on same twig. Staminate in aments which develop partly in previous autumn 

 d remain dormant over winter. In Avinter they are stiff, pendant, greenish, and about 

 e inch long; in clusters of 2-5 at the end of bare stalks. Pistillate also develop in the 

 3vious autumn and remain doimaiit over winter, are about i-i of an inch long, usually clustered 

 2s or 3s and greenish to purplish in color. The first warm days of spring bring forth 

 i scarlet styles of the pistillate flowers. 



TRUIT — A cone-like woody structure, about i-| of an inch long, orbicular, persistent, 

 aiposed of thick and woody scales on which the little, practically wingless, round and 

 ttened nutlets arc pioduced. 



WOOD — Diffuse-porous: growth rings distinct; rays variable in width. Sapwood turns 

 llowish-brown upon exposure. 



DISTINGUISHING CHARACTERISTICS— The Smooth Alder, also known as Black Alder, 

 Q be distinguished by the woody cone-like fruit which is usually present at all seasons of 

 8 year. The wet habitats which it frequents may also aid in recognizing it. In spring it is 

 e of the first of our small trees to blossom. In summer the stiff leaves with their rounded 

 exes are also characteristic. In winter the mature fruit, developing staminate and pistillate 

 wers, stalked bud.-;, and triangular green pith, are distinctive. The only other Alder 

 tive to Pennsylvania is the Speckled or Hoary Alder (Alnus incana (L.) Moench.) This 

 ecies can be distinguished from the Smooth Alder by its leaf-blades which are usually 

 lucous or finely pubescent and rounded at the base. 



RANGE — Essentially a southern species, extending from Maine to Florida and Texas and 

 istward to Minnesota. 



DISTRIBUTION IN PENNSYLVANIA — Very common in the eastern and southern parts 

 the State. Sparse and locally abundant in northern and western parts. 



HABITAT — Common along streams and in swamps. Rarely ascends the hillsides. In wet 

 tuations it often forms dense thickets. 



IMPORTANCE OF THE SPECIES — The two species of Alder native to Pennsylvania do not 

 tain a size which would make them important commercially. They may be of value as 

 il-biuders and soil-ccnservers along the banks of streams or in very wet situations siuce 

 ey develop large and strong roots which throw off many suckers, 



