Alnus. 



BETULACEJE. 



mi 



slightly lobed or rather coarsely and obtusely toothed on the margin ; the teeth finely serrate ; 

 the secondary veins strong and prominent. Stipule brown, pubescent. Fertile aments usually 

 4 - 5, in a paniculate raceme. Scales or bracts thickened at the tip ; the scales of the calyx 

 closely adnate, except at the summit. Fruit with a thin but not winged margin. 



Borders of rivulets in the Catskill mountains. Banks of Esopus creek, near Saugerties 

 (Mr. J. Carey). Fr. August. This species is also indigenous to Europe, and the northern 

 parts of New-England and Canada. 



** Alnaster, Spach. Fruit winged. 



3. Alnus viridis, DC. (Plate CXVI.) Mountain Alder. 



Leaves oval or ovate, obtuse or acute, rather obtuse at the base, doubly serrate, glutinous 

 and pubescent underneath, or only the veins and axils pubescent ; stipules broadly ovate ; 

 fertile aments on long pedicels ; fruit with a broad winged margin. — DC. fl. Fr. 3. p. 304 ; 

 Cham, in Linncea, 6. p. 538 ; FLook.fl. Bor.-Am. 2. p. 156. A. incana, Hook. I. c. (in part). 

 A. undulata, Willd. sp. 4. p. 336. A. ovata, Lodd. bot. cab. t. 1141 (ex Loud.). A. crispa, 

 Tuckerm. I. c. p. 33. A. Mitchelliana, Custis, ms. (ex Gray in Sill, journ. 42. p. 42). 

 " Betula viridis, Vill. Delph. B. ovata, Schrank, fl. Bavar. 1. p. 419." B. crispa, Ait. 

 Kew. (ed. 1.) 3. p. 339. B. -Alnus crispa, Michx. fl. 2. p. 181. Alnaster viridis, Spach, 

 I. c. p. 200. 



A shrub 4-8 feet high, much branched ; the branches often sprinkled with little warts. 

 Leaves 2-4 inches long, varying from oblong-ovate to broadly cordate, deep green above ; 

 the under surface more or less pubescent (particularly on the veins), and covered with a thin 

 resinous substance which causes the leaves to adhere to the paper when they are pressed ; 

 the margin sometimes obscurely lobed, finely and very sharply serrate. Fertile aments ovoid, 

 obtuse, nearly three-fourths of an inch long ; the pedicels often nearly an inch in length. 

 Fruit with a broad membranaceous margin like that of a Betula. 



Along the mountain streams of Essex county. Fr. August. Our plant agrees well with 

 my European specimens, but differs somewhat from the A. viridis of the Northwest Coast, 

 in the leaves being only doubly serrate, and not somewhat incisely lobed. It is the type of 

 Spach's genus Alnaster ; but notwithstanding the peculiarity of the fruit, it is a true Alnus, 

 In A. rubra, Bong, (of Sitcha), the fruit is also winged, but less broadly than in A. viridis, 



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