488 BOTANY. 



The bark of B. papyracea, of the Eastern United States, is used by 

 the Indians for making their " birch bark canoes." 



The wood of species of Alnus, the Alders, is very durable when 

 placed under the ground or water. It is also made into wooden bowls 

 and other domestic utensils, and is in some places grown for making 

 into charcoal. 



576. Cohort VIII. Urticales. Mostly diclinous plants, 

 with superior one-celled ovary, and single seed mostly with 

 an endosperm. 



Order TJlmacese. The Elm Family. Trees or shrubs of the North 

 Temperate Zone, having mostly monoclinous flowers, and a watery 

 juice. About one hundred and thirty species are known. 



Ubmvs campestris, the common Elm of Europe and Western Siberia, 

 is a large tree, thirty to forty metres (100 to 130 ft.) high. Its timber is 

 valuable for works underground or in water, and is besides much used 

 by wheelwrights. The tree is common in American gardens. 



V. Americana, the American White Elm of the Eastern United 

 States, and now much grown in Europe, is one of our finest looking 

 trees, and deservedly popular as an ornament in large grounds. Its 

 timber is valuable when used entirely under water or in the ground, 

 or when kept continuously dry ; otherwise it decays rapidly. 



U. fulva, the Slippery Elm of the Eastern United States, supplies a 

 valuable timber, and its mucilaginous inner bark is used for medical 

 and surgical purposes. 



Celtis occidentalis, the Hackberry of the Eastern United States, is a 

 lofty tree which furnishes a white hard timber, which is not, however, 

 very durable. 



Order Cannabinese. This contains the two dioecious herbs, the 

 Hemp and the Hop. 



Cannabis sativa, the Hemp, is a tall herb, two to three metres (7 to 

 10 ft.) in height, indigenous in the northern parts of India, but now 

 generally cultivated in all temperate and warm regions. Under the 

 names of gunja, bhang, churrus, haschisch, etc., the natives of India and 

 Central Africa use the dried leaves, stems, flowers, and the resinous 

 matter which develops on the plant. When smoked, or drank as an 

 infusion, these are highly intoxicating. The fibre obtained from its 

 bark is strong, and much used for cordage. 



Humulus Lupulus, the Hop, a native of temperate Europe, Asia, and 

 North America, is grown for its bitter principle, Lupulin, which de- 

 velops in the female flower clusters, and which is much used in the 

 manufacture of beer, ale, etc. 



Order Moracese. The Mulberry Family. Trees or shrubs, con- 

 taining a milky juice. The order contains between 800 and 1000 spe- 

 cies, and they are for the greater part natives of the tropics. Many 



