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Trees of Wisconsin

Thuja occidentalis L.
white cedar; arbor vitae
Family: Cupressaceae

Arbor Tree Arbor Leaves Arbor Trunk Arbor Bark
trees leaves trunk bark deer browse
Arbor Cones

male cones
(before anthesis)

male cones female cones
(in flower)

female cone
(partial dissection)

female cones

Thuja occidentalis is easily recognized. The leaves are small, scale-like and tightly appressed to the branches. The leaves are of two distinct types, the first flat and broad and the second appearing folded and narrower. They are arranged as shown above to create a strongly flattened appearance to the twigs. Male and female flowers are found in separate cones that are so small as to frequently go unnoticed (see photos above). After anthesis (the act of dispersing pollen) the male cones quickly wither. The flowering female cones persist and eventually develop a few woody scales oppositely arranged and containing seeds in their axils (the acute angle formed by the scale and the central axis of the cone). Flowering begins about mid-April in upland sites in Brown County.

Thuja occidentalis ranges from Ontario and northeastern Minnesota to Nova Scotia, south through Wisconsin to northeastern Illinois, Michigan and New York and at scattered locations as far south as North Carolina in the Appalachians. In Wisconsin it is most common in the northern half of the state and farther south in the east along Lake Michigan. It is most often found on calcareous sites, including the thin soils of Door County and other eastern Wisconsin sites underlain by dolomite. It is also prominent in swamps where it may be the dominant species. Thuja occidentalis is not reproducing well in Wisconsin, at least in part due to the large numbers of deer which find the leaves highly palatable, thereby reducing the survival of seedlings to a very small number in some areas.

WI Distribution Map


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