Tree of the Week: Arrowwood (Viburnum dentatum)

 

This week we are studying a grouping of plants located on the west side of Mickle Hall. Planned renovations to Mickle will result in major changes in this area of the arboretum: the building will expand outward into the landscape, which means that all of the above vegetation will be removed, along with the shed. So, let's examine a few of the plants in this area.

 

In February of 1985, Jack Price donated five arrowwood (Viburnum dentatum) plants to the arboretum collection. They were planted in this spot, at the top of a steep slope, which, at this time, is a sunny location. We cannot say if any of the original five plantings are still with us; however, at minimum, this species has persisted, mostly as shrubs, rather than trees, for over 38 years. The arrowwood shrubs have required regular pruning of dead or drooping branches. A thick stem would die, but then a new shoot would appear. Today, we have three thin shrubs, one 'tree' with a crooked trunk, and a few seedlings in the leaf litter.

The arrowwood shrubs are extra special this week because of the clusters of pretty flowers.

The arboretum sign marks an arrowwood shrub. Rather than one thick trunk, we see four stems, and all four stems have some age on them―the bark is mature; rough and peeling.

 

Viburnum dentatum, mature bark

 

Viburnum dentatum, mature bark

 

This photo shows that pruning has been necessary.

In the first half of May, we are seeing bunches of beautiful white flowers.

The flowers are numerous and pleasing to view, but they do not have a pleasant fragrance.

Viburnum dentatum, flowers and leaves

Viburnum dentatum, flower cluster

 

Two twigs were snipped for inspection. An inflorescence appears at the tip of one twig. Leaves are a dark, rich green, with dentate margins. Twigs and leaves are fuzzy!

 

Underneath, leaves are lighter green, and we see that the leaves are opposite.

This inflorescence measures approximately 2 inches across. Flowers are tiny.

 

This leaf has an ovate shape and measures approximately 2½ inches in length. The toothed margins aren't as noticeable in this picture.

 

This leaf is in the shape of a circle and measures 1¾ inches across.

This leaf is heart-shaped and measures 2¼ inches across. The dentate margins are very noticeable in this photo.

Viburnum dentatum, variable leaf shape but all are fuzzy

 

For quite some time, at minimum 10 years, a dewberry patch (Rubus trivialis) has thrived under the protection of this grouping of arrowwood. Annually, it produced handfuls of delicious black berries. This year, the patch looks thinner than usual because back in March, two toothache trees (Zanthoxylum clava-herculis) were removed from this spot and transplanted elsewhere in the arboretum.

 

There are only a few scattered ripe fruits today. This patch is almost finished for the year.

Rubus trivialis, fruit

 

Rubus trivialis, fruit and leaves

 

Spiderwort (Tradescantia hirsutiflora) has also thrived alongside the dewberry. Two groupings of spiderwort have been cultivated, although it would prefer to thoroughly intermix with the dewberry. Both spiderwort and dewberry are common in the arboretum, and, happily, the arrowwood shrubs have been reproductively successful, as there are multiple arrowwood volunteers in the arboretum collection. So, from this grouping of plants, the arboretum catalogue will not lose a unique species with the proposed expansion of Mickle Hall.

 

 

Tree of the Week: Arrowwood Viburnum (Viburnum dentatum)

The arrowwood viburnums (Viburnum dentatum) are currently flowering in the arboretum. As shown in the photo above, this species produces large clusters of tiny white flowers. The individual pictured above is our tree of the week—one of seven arrowwood volunteers.

Our tree of the week grows on the west side of Mickle Hall, at the top of a slope in a mostly sunny location. This specimen is at least 14 years old. Over the years it has been trimmed to resemble a multi-stemmed small tree, but it would have preferred to grow as a large, spreading shrub.

Not all of the arrowwood viburnums are flowering as marvelously as this one. The other six volunteers, for the most part, are sparsely decorated, perhaps because of their low-light growing conditions.

A frantic pollinator was also examining this particular arrowwood. These beautiful flowers have a definite fragrance, but not a pleasant one.

A few twigs were snipped for closer inspection. An individual leaf is about the same size as a flower cluster.

Arrowwood viburnum twig

This flower cluster measures more than 3½ inches wide.

The fresh, velvety leaves appear opposite from one another along the twig.

Opposite leaf arrangement of arrowwood viburnum

Twigs and leafstalks are textured, not smooth. Leaves are noticeably soft and fuzzy.

Leaf shape varies. On the left, we have an orbicular shape with an obtuse tip. The center leaf has a more characteristic deltoid shape. On the right, a cordate shape is apparent. But for each leaf, the margins are toothed (dentate).

The upper surface is green while underneath, leaves are light green, almost white.

These new leaves vary in size, ranging from 3 to 3½ inches wide.

Our center leaf is 3¼ inches wide.

Leafstalk measures ½ inch long, and the leaf measures 3⅜ inches long.

The slender trunks have dark grey bark.

One year ago today this same little tree was flowering. You can see proof here.

You can find additional photos of the arboretum's arrow wood viburnums here. 

For more information about this species consult the following:
United States Department of Agriculture
Louisiana Plant Identification and Interactive Virtual Tours (LSU AgCenter)
University of Arkansas

Winter Fall Foliage: Arrow Wood

Fall foliage of the arrow wood viburnum (Viburnum dentatum) can still be seen after the winter solstice.

Yellow and red leaves of the arrow wood viburnum

This grouping of arrow wood started out as a few volunteer saplings, first noted in 2009. This spot was initially designated for Virginia willow (Itea virginica), which remains and continues to spread.

Arrow wood fall foliage

Yellow leaves with reddened 'teeth'

Springtime Flowers

The arrowwood viburnum (Viburnum dentatum) is covered in blossoms this week.

This shrubby tree is growing in full sun on a slope. Other arrowwood viburnums have volunteered in very shady locations: they are growing taller in the shade, but they do not have as many blossoms.

New Leaves

Ashe's viburnum (Viburnum ashei)

Arrow wood viburnum (Viburnum dentatum)

Toothache tree (Zanthoxylum clava-herculis)