Trees of Xnr Tori- Sialr 363 



KEY TO THE GENERA page 



1. Staminate and pistillate flowers in ament-like spikes Morus 363 



1. Staminate tlowers raeeino.se; pistillate flowers capitate 2 



2. Leaves erenate-serrate or variously lobed, fruit 2-5-1 inch in diameter; 



twigs unarmed Broussonetia 363 



2. Leaves entire; fruit 3-5 inches in diameter; twigs armed Madura 364 



THE MULBERRIES. Genus MORUS (Tourn.) L. 

 Morus is represented by six or seven species of trees with milky 

 sap, scattered over the tropical and temperate zones of both the 

 eastern and western hemispheres. Two species are found in the 

 United States, the Red Mulberry with a wide distribution east 

 of the great plains, and a southwestern form. The White Mul- 

 berry, a native of northern China and Japan, wa.s introduced 

 in an attempt to establish the silk industry and has become widely 

 naturalized in the eastern states. 



Leaves alternate, deciduous, simple, entire, serrate or variously lobed, 

 3-uerve(l at the base; stipules enclosing the leaf in the bud, lanceolate, cadu- 

 cous. Flowers monoecious or dioecious, the staminate and pistillate on 

 different branches of the same plant or on different plants, vernal, in peduncu- 

 late clusters from the axils of caducous bud-scales or the lower leaves of the 

 year; staminate flowers in elongated cylindrical spikes; calyx with 4 rounded 

 lobes ; stamens 4, inserted opposite the lobes and intlexed in the bud, straight- 

 ening elastically at anthesis and becoming exserted ; rudimentary ovary 

 present; pistillate flowers sessile, in short compact spikes; calyx 4-parted with 

 thickened ovate or obovate valvate lobes (outer pair longest) enveloping the 

 tlattoned ovoid ovary; styles 2, white, spreading. Fruit a multiple, fleshy 

 syncarp resembling a blackberry, consisting of many druplets each enclosed 

 in the succulent, thickened, colored calyx and cro^^^^ed with the style rem- 

 nants; seed penduluous, albuminous. 



KEY TO THE SPECIES page 



1. Leaves glabrous beneath or sparingly pubescent on the veins; fruit white or 



pinkish white M. alba 215 



1. Leaves soft pubescent beneath, fruit reddish purple M. rubra 213 



THE PAPER MULBERRY. Genus BROUSSONETIA L'Her. 



Broussonetia includes three or four species of trees or shrubs 

 with milky juice, alternate or opposite entire or lobed leaves, 

 capitate clusters of pistillate flowers, and fibrous inner bark. One 

 species, Broussonetia papyrifera (L.) Vent., has became widely 

 naturalized in the temperate portions of the United States. 



Leaves alternate, deciduous, simple, entire, serrate or variously 1-5-lobed, 

 3-nerved at the base, long-petioled. Floivers dioecious, vernal, the staminate 

 in oblong, cylindrical, nodding, ament-like spikes; the pistillate in capitate 

 clusters; staminate flowers with 4-part€d calyx; stamens 4, inserted opposite 

 the lobes, exserted at anthesis; rudimentary ovarj^ present; pistillate flowers 



