60 Rhodora [Marcu 
In West Virginia Thuja is known from but two localities, in the 
extreme Northeast: Knobly Mountain in Mineral County and near 
Petersburg in Grant County! Knobly Mountain extends across 
Mineral and Grant Counties and consists, according to Darton & 
Taff, of Silurian limestones and calcareous sandstones,’ while Peters- 
burg is on the South Branch of the Potomac, which drains these and 
the calcareous Devonian sandstones and shales. 
“This is about the rarest tree in North Carolina... .It is said to 
occur in only a few places, as on Cripple Creek and Linville River, 
on limestone soil” *; while in Tennessee it is only “along Holston 
River [see above] in the mountains," * the Holston in Tennessee 
flowing through a highly calcareous region, the rocks, as indicated 
by Keith,’ being chiefly Cambrian and Silurian limestones. 
In Ohio Thuja is known only in “Champaiga, Franklin, Greene, 
Highland, Adams" counties; * Orton, on his map of the Limestone 
Formations of Ohio, showing Champaign and Greene Counties as 
wholly limestone, Highland and Adams almost wholly so, and the 
western half of Franklin County calcareous. 
In Indiana Thuja is known only in Lake County,’ which is Silurian, 
although thinly covered at the north by the wind-blown sand-dunes 
beside Lake Michigan. The “Tamarack-Arbor-vitae swamp is on 
the eastern boundary" of the sand dunes where Pinus Banksiana 
abounds, but not on the dunes themselves. Here, however, Nieuw- 
land informs us, “The Arbor-vitae trees are not in the best of con- 
dition,” ° although he ascribes their poor condition to the cutting of a 
ditch some distance away. 
So much for the southern colonies of Thuja occidentalis. Now 
turning in the opposite direction we find a strikingly similar restriction 
to calcareous soils of the extreme northern colonies. 
In Labrador, Low states that “ Thuja occidentalis Linn. (Cedar) 
hardly enters the southern limits of the peninsula. It occurs just 
south of the mouth of the Rupert River, at the foot of James Bay, 
1 Millspaugh, Living Flora of W. Va. 199 (1913). 
2 Darton & Taff, Piedmont Folio (no. 28), Geol. Atlas U. S. (1896), 
3 Coker & Totten, Trees of N. C. 26 (1916). 
! Gattinger, Flora of Tenn. 32 (1901). 
5 Arthur Keith, Morristown Folio (no. ?7), Gecl. Atlas U. S. (1896). 
5 Shaffner, Cat. Ohio Vasc, Pl. 136 (1914). 
? Orton, Geol. Surv. Ohio, ser. 4, Bull. no. 4 (1906). 
8 Deam, Indiana State Bd. Forestry, Ann. Rep. xi. 110 (1912). 
? Nieuwland, Am. Mid. Nat. ii. 165 (1912). 
