FAMILIES OF FLOWERING PLANTS. 



81 



grain and color. Next in importance to the Avood of the oak is its 

 bark, which is very rich in tannin, and hence is employed in the manu- 

 facture of dye-stuffs and in tanning. The bark of Quercus Siiher^ a 

 native of southern Europe, furnishes the cork of commerce. Acorns, 

 as the fruits of the oak are commonly called, are sometimes eaten as 

 food; they afford by their shape and size the surest method of dis- 

 criminating between species that otherwise closeh' resemble each other. 

 Fagax, the beech, is another timber tree of great beauty, and often 

 forms extensive tracts of forest in our Eastern states and in Europe. 

 Like Castanea, the chestnut, it is a small genus, comprising only four 

 or tive species. The chestnut is und()nl)tcdly the most highly esteemed 

 of our native nuts, being equally palatable to the sijuirrel and the 

 small boy. 



It will be noticed that in I)oth Betuhiceae and Fjignceae the flowers 

 are adapted for wind rather than insect fertilization. This is true to a 

 larofe extent in the families belon<2:ini; to the followino- order. 



Fig. H6.— The American elm (I'hnnn Ameri- 

 cana) showing flowers and fruit. After Britton 

 and Brown, III. Fl. Northeast U. S. 



CHAPTER XV. 



Orderx Urticales and Protealrx. 



The Urticales have the flowers 

 variously clustered, or rarely even 

 solitary, l)ut not borne in aments 

 as in the Fai^ales. The fruit is an 

 achene,* a drupe or stone-fruit, or 

 a berry, never a nut. The order 

 consists of three families — Uhna- 

 ceae, Moraceae and Urticaceae, 

 The order Proteales, which is con- 

 flned to the southern hemisi)here, 

 is restricted to the single family 

 Proteaceae. 



Family Ulmaccae. Elm Fami- 

 ly. Contains about 13 genera and 

 140 species, of wide distrii)ution in 

 both temperate and tropical re- 

 Ulinw<^ the elm, is noted 



gions. 



*Achene is a name given to a small dry one-seeded fruit that does not split open 

 (indehiscent) wlien ripe. 



