QUERCUS 



erect catkins with 4-7-parted calyx and 4-12, usually 6, 

 stamens; pistillate in 1-many-fld. spikes in the axils of 

 the young Ivs., rarely at the base of the axillary stami- 

 nate catkins, each flower consisting of an incompletely 

 3-celled ovary, surrounded by imbricate 

 bracts: fr. a 1-seeded subglobose to oblong 

 nut, surrounded at the base or sometimes al- 

 most inclosed by a cup-like involucre. 



The numerous species have been divided 

 into different subgenera. All American spe- 

 cies, except Q. d?nxi flora, belong to the sub- 

 genus Lepidobalanus (balanos is Greek for 

 "acorn"), which is characterized by slender, 

 pendulous, staminate catkins, separate axil- 

 lary pistillate spikes and a cup consisting of 

 bracts of various shape but not connate into 

 zones. Q. dens i flora belongs to Pasania, 

 which has erect staminate catkins, some bear- 

 ing pistillate tts. at their base, like the catkins 

 of Castanea. Cyclobalanus and Cyclobala- 

 nopsis have the scales of the cup connate into 

 concentric rings; the inflorescence of the first 

 being similar to that of Pasania, of the second 

 to Lepidobalanus. Chlamydobalanus is much 

 like Cyclobalanus, but the nut is wholly in- 

 cluded by the ovate cup. Of Lithocarpus, 

 with the nut partly connate with the cup, but 

 otherwise like the last-named subgenus, no 

 species is in cultivation. The oaks of the 

 subgenus Lepidobalanus are divided into 

 two sections, Leucobalanus and Melanoba- 

 lanus. In the former, comprising the White 

 Oak tribe, the acorns mature the first year 

 (Fig. 2039). In the latter, comprising the 

 Black Oaks, the acorns mature the second 

 year (Fig. 2040). Besides the 300 species, 

 about 40 hybrids have been recorded. The 

 latest monograph of the whole genus is by 

 A. DeCandolle in Prodromus, vol. 16, 2, pp. 

 1-108 (1864-1868). Important illustrated works on Amer- 

 ican Oaks are A. Michaux, "Histoire des Chenes de 

 1'Amerique " (1801), with 36 plates ; Kellogg and Greene, 

 "Illustrations of West American Oaks" (1889), with 37 

 plates; Sargent," Silva of North America," vol. 8 (1895), 

 with 82 plates, and Liebmann, "Chines de PAmerique 

 tropicale" (1869), with 47 plates. Most of the European 

 and west Asian Oaks are figured in Kotschy, Eichen 

 Europas und des Orients (1862), with 40 colored plates. 



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1477 



wagons, tools and many other articles. The bark of 

 some species, in America that of Q. velutina, Prinus 

 and densiflora, is used for tanning leather. Cork is 

 obtained from the bark of Q. Suber and occidental in 



1, Q. 



2041. Leaves and acorns of various Oaks. 

 Phellot; 2, Q. alba; S, Q. velutina; 4, Q. rubra; 5, Q. Prinut; 

 6, Q. macrocarpa; 7, Q. bicolor. 



southern Europe. The bark of a few species has also 

 been employed in medicine. The acorns of several spe- 

 cies are edible, in America especially those of Q. 

 Michauxi, Emory i and lobata; in Europe those of Q. 

 Ilex, var. Ballota and ^Egilops; in Japan those of 

 Q. glauca; in many European countries the acorns of 

 all species are an important food for hogs. In eastern 

 Asia a silkworm feeds on the leaves of different species. 

 A parasitic insect living on Q. coccifera in southern 

 Europe and N. Africa yields a scarlet dye. Galls caused 

 by the puncture of certain insects are used for tanning 

 and dyeing and are now chiefly obtained from Q. Ilex, 

 var. infectoria in western Asia. Some of the above men- 

 tioned species are described only in the supplementary 

 list, p. 1483. See Oak. 



2 40. Biennial-fruited oak 

 Quercus velutina ( X M ) . 



The mature acorn is borne 

 on two-year-old wood: that 

 is, the acorn does not ma- 

 ture until it is two years 

 old. See No. 6. 



The Oaks comprise some of the most important forest 

 trees of the northern hemisphere. The wood of most 

 species is strong, tough, hard and durable, and highly 

 valued for many purposes, especially ship-building, 

 construction, for furniture, and in the manufacture of 



