204 TREES IN WINTER 



THE OAKS 



Quercus. 



The Oaks form a large genus, of which 52 are North American. Of 

 these, 12 are native to New England. Buds clustered at ends of twigs, 

 more or less 5-sided pyramidal, covered with 5 rows of closely over- 

 lapping brownish scales. Leaf-scars concave to rounded above, round- 

 ed at base, generally broader than high and raised with a ridge more 

 or less well marked, decurrent from lower edge, the ridges from the 

 5 ranks of leaf-scars causing twig to be more or less 5-angled 

 especially when dried. Bundle-scars irregularly scattered, inconspicuous. 

 Stipule-scars inconspicuous. Pith of cut twig 5-poihted, star-shaped. 

 Cross-section of branch or trunk showing layers of large, porous spring 

 wood alternating with dense layers of summer wood. Medullary rays 

 of wood very prominent, showing as radial lines in cross section of a 

 log, also generally showing prominently, especially through a hand- 

 lens, on cut end of stout branchlet of several years growth. Fruit an 

 acorn inclosed in a scaly cup. Dead leaves often persistent on the 

 tree during winter. 



Key to Oaks based upon fruiting material. 



109. Fruit maturing in autumn of second year, ripe acorns therefore 

 borne upon parts of twig two years old; immature acorns to be 

 found in winter on twigs of the past season's growth; shell of 

 nut hairy inside; abortive ovules at the top of the nut; scales 



of acorn-cup broad and thin; lobes of leaves bristle-pointed 



Black Oaks 110 



109. Fruit maturing in one year, ripe acorns therefore borne upon past 

 season's growth; no immature acorns to be found upon twigs in 

 winter; shell of nut smooth inside; abortive ovules at base of nut; 

 lower scales at least of acorn cup more or less thickened at base 

 giving a knobby appearance to surface of cup; scales more or less 

 densely woolly; kernel commonly sweetish; lobes of leaves not 



bristle-pointed; bark flaky except in Chestnut Oak 



W^hite Oaks 114 



110. Cup of acorn shallow saucer-shaped Ill 



110. Cup top-shaped 112 



111. Cup thin, 15 mm. or less wide; buds 4 mm. or less long 



Pin Oak (Quercus palustris) p.314 



111. Cup thick, 20 mm. or more wide; buds over 4 mm. long 



Red Oak (Quercus rubra) p.312 



112. Buds under 4 mm. long; twigs slender; shrubs 



Bear Oak (Quercus ilicifoliaj p.320 



112. Buds over 4.5 mm. long; twigs rather stout; trees 113 



113. Upper scales of cup loosely overlapping; buds pointed, whole 



surface woolly; inner bark yellow 



Black Oak (Quercus velutina) p.318 



113. Upper scales of cup closely overlapping; buds blunt, downy above 

 middle; inner bark pale red. Scarlet Oak (Qtiercus coccinea) p.316 



114. Upper scales of cup with thread-like outgrowths forming a 

 fringe to cup; branchlets often with corky ridges; lateral buds 

 frequently appressed Bur Oak (Quercus macrocarpa) p.302 



114. Cup without distinct fringe; branchlets without corky ridges; 

 lateral buds divergent " 115 



115. Bark on branchlets peeling back in dark stiff-papery layers; 

 marginal scales of cup narrow awn-pointed; acorns long-stalked. 

 Sfvamp White Oak (Quercus bicolor) p.304 



115. Bark on branchlets not peeling back in dark stiff-papery layers; 

 acorns sessile or short-stalked (at times long-stalked in White 

 Oak) 116 



116. Buds sharp-pointed 117 



116. Buds blunt 118 



