POPULUS — POPLAPv. 255 



with long hairs. A tree, 20 to 50 feet high, with smooth, greenish-white 

 bark. Leaves roundish- cordate, acuminate, serrate, smooth both sides, 

 downy on the margins ; petioles long, slender, laterally compressed, so 

 that the gentlest breeze suffices to keep the leaves constantly agitated. 



Habitat. — In woods and copses ; common. 



Populus balsamifera Linnd — Balsam Poplar, Tacmahac. 



Description. — Scales of the catkins dilated, slightly hair}-. A tree, 40 to 

 80 feet high. Leaves ovate, acuminate, serrate with appressed teeth, 

 smooth both sides, green above, white and reticulate-veiny beneath. In 

 spring the buds are covered with an aromatic resin. 



Habitat. — In moist soil, Northern New England to Wisconsin and north- 

 ward. 



A variety of this species (P. candicans Aiton — Balm of Gilead) differs in 

 having the leaves broader and somewhat cordate ; it is common in cultiva- 

 tion as a shade tree. 



Parts Used. — Of P. tremuloides, the bark ; of P. balsamifera the resin- 

 ous exudation of the buds — neither is official. 



Constituents. — The bark of all species of poplar contains a crystalline 

 principle, termed populin, closely resembling salicin. The resin of the 

 balsam poplar does not differ materially in composition from other aro- 

 matic resins. 



Preparations. — Poplar bark is commonly administered in decoction or 

 infusion. The resin of the balsam poplar is readily separated from the 

 buds by boiling them in water ; it may then be dissolved in alcohol, and 

 administered in. this form, or a tincture of the entire buds may be em- 

 ployed. 



Medical Properties and Uses. — Poplar bark is a bitter tonic, acting like 

 willow-bark, and possessing feeble antiperiodic properties. It is little 

 used. 



Poplar balsam is reputed tonic and stimulant. It was formerly used 

 to a limited extent in pharmacy, to prevent ointments becoming rancid. 



CONIFERS. 



Character of the Order. — Monoecious, rarely dioecious, trees or shrubs ; 

 flowers in catkins, destitute of calyx and corolla ; stamens inserted on the 

 axis of the catkin under the scales, or the anther-cells are sessile on the 

 scales themselves ; ovules and seeds naked. Leaves mostly awl-shaped or 

 needle-shaped. Juice commonly resinous. 



A large order, dispersed over all parts of the globe, most abundant 

 in temperate regions, but extending also to the tropics and frigid zones. 

 It comprises three well-marked sub-orders, namely : Abietineae, Pine 

 Family; Cupressineee, Cypress Family ; Taxineae, Yew Family. 



