47. Kousa Dogwood

Also called the Japanese Dogwood

Specimen Size: 23.8ft tall, 5.25in in diameter.

Location: West of Denny Hall, just south of the central wing of the building.

Historical Background: A native of Japan and central China, this very pleasant tree is well noted for its autumn color. A great ornamental, the species had been introduced to commerce in the United States by 1871, although earlier clippings had made it to country prior to that point and, when compared to the related eastern dogwood by botanists, helped lend credence to the then controversial “Origin of Species” published in 1859 by Charles Darwin. One interesting trait of the Kousa Dogwood is that it produces fruit which is edible, both raw and cooked, a feature not shared amongst many other dogwoods (which produce fruit toxic to humans). The skin is tough but the interior is said to be quite delightful, although the presence of many drupes can make eating them an exercise in patience as one spits out seeds. They generally appear in late summer (although recent heat and droughts due to climate change appears to prevent successful fruiting on this particular specimen).

Non-native

Native Range: Native to Japan and Central China.

Identifying Features light: A small tree with low apical control, this species generally achieves heights of just 32’ (10m), with wide spreading branches. The leaves have the distinctive trait of dogwoods, that being pinnate venation where the secondary veins curve parallel to the edges of the ovular leaf. When pulled gently in half widthwise in the center of the leaf, the two halves will remain held together by thin stands emanating from each vein. Another distinguishing feature is of course the large showy white bracts which accompany flowers in this genus. This creamy floral display is but one of the colorful displays put on by this tree. The fruits are bright orange-pink and can be very abundant, and in fall the leaves turn a stunning shade of red, and even in summer the leaves have an extremely pleasant variety of green shades depending on shading.

Identifying Features In Depth:

1. Form: A small tree up to about 32’ (10m) in height, with an open irregular crown of dense foliage. The whole tree may appear to droop in cases where it has been impacted by severe heat or drought, which may be a factor in future years as climate change impacts the Pacific Northwest.

2. Leaves: The leaves are ovoid, about 3” (8cm) in length and more elliptical than their North American cousins, tapering to a long graceful point. Veins are pinnate, and secondary veins run parallel to the leaf edge, which is smooth. They grow opposite and are variable in size, glabrous except for tufts on the axils. The tops are a shiny green, the buttons duller or even gray in color. The bracts surrounding flower clusters of this species are distinct from those of the two dogwoods seen earlier in this tour. They are pointed, unlike the Pacific dogwood which has rounded bracts and the Eastern dogwood which has notches on the tips of its bracts.

3. Bark: Very pleasant, a variety of reds and tans with new colors revealed as the bark flakes, much in the same fashion as the sycamores which will be seen shortly on this tour.

4. Reproductive Bodies: Small flowers clustered together in a ball and held up by upright shoots are surrounded by the showy white bracts of the dogwood. These flowers give rise to rounded fruits of an orange pink color, on a long petiole about 5mm long. The fruits are strawberry like, with many fleshy drupes clustered together ripening in late summer.