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ARBOR VITAE. 



Thuja occidentalis, Linnaeus. 



GENUS DESCRIPTION This genus comprises 4 known species In the world, of which number 

 2 are found in North America. One of the 2 species native to North America is found in the 

 eastern part, and the other in the western part. The specis found in the western part attains 

 a large size, while the one found in the eastern part usually remains a small tree. They are 

 best known as ornamental trees but furnish some lumber, which is very valuable on account of 

 its great durability. The bark also yields tanning material and the twigs and leaves contain a 

 volatile oil which possesses stimulating properties. 



FORM A medium-sized tree usually attaining a height of 20-50 ft. with a diameter of 1-2 ft. 

 but may reach a height of 75 ft. with a diameter of 3-4 ft. 



TRUNK Tapering, furrowed, buttressed and often divided. Crown dense, conical, very high, 

 and often covered with foliage almost to the base. 



BARE Grayish to reddish-brown, thin, furrowed, separating into long rather thin, fibrous and 

 often persistent strips. 



TWIGS Yellowish-green, evidently flattened, somewhat 4-sided, completely covered by closely 

 adhering leaves, zig-zag or arranged in fan-shaped clusters. 



BUDS Leaf-buds not scaly, covered by closely adhering scale-like leaves. 



LEAVES Opposite, scale-like, closely overlapping, aromatic when crushed, with very conspic- 

 uous glandular spots on the thrifty shoots, i of an inch long, of two kinds in alternating 

 pairs. Those on the side, of the twigs keeled; those on the face of the twigs flat. 



FLOWERS Appear about April or May. Staminate and pistillate flowers usually occur on 

 different twigs. Staminate roundish, inconspicuous and yellowish. Pistillate small, ovoid, pur- 

 plish, with 4-6 paira of thin oval scales. 



FRUIT An oblong cone with 6-12 obtuse scales, J- of an inch long, reddish-brown, matures 

 in one season. Seeds oblong, winged, about i of an inch long. 



WOOD Non-porous; resin passages absent; light, soft, durable, fragrant; sapwood almost 

 white, heartwood yellowish-brown. Weighs 19.72 Ibs. per cubic foot. Used for fence posts, rails, 

 shingles, spools, .and railroad ties. 



DISTINGUISHING CHARACTERISTICS The Arbor Vitae, also known as White Cedar 

 and Cedar, may be distinguished at any season of the year by its scale-like and closely overlap- 

 ping leaves from all the other trees native to the State of Pennsylvania except the White 

 Cedar. It can be distinguished from the latter, which also has scale-like leaves, by its more 

 flattened and larger twigs, which are also more fan-shaped. The fruit of the Arbor Vitae is 

 oblong with thin oblong scales, while that of the White Cedar is spherical with thick shield-shaped 

 scales. 



RANGE Southern Labrador west to Manitoba and Minnesota, and south along the mountains to 

 North Carolina and eastern Tennessee. 



DISTRIBUTION IN PENNSYLVANIA The Arbor Vitae is found to the north and south of 

 Pennsylvania, but so far no authentic records are available which show that it is native to this 

 State. It is, hcwever, found very commonly throughout the entire State as an ornamental tree 

 and sometimes as a hedge. 



HABITAT Usually found in low swampy situations on the borders of ponds, streams, and lakes, 

 but occassionally ascends to drier ground. In the north it is often found in the sphagnum bogs 

 with Spruce and Kir, while in the south it is usually found on the mountain slopes and tops with 

 the Spruce and other coniferous species. 



IMPORTANCE OF THE SPECIES The Arbor Vitae is one of our most valuable species for or- 

 namental purposes. It is common throughout the State as an ornamental tree and occasionally 

 planted for hedges. As a timber tree, however, it is surpassed by many other native species and 

 should be planted for forestry purposes only in such habitats where other more valuable species 

 will not grow. 



