Native Plant of the Month – November

November 2018 – Native Plant of the Month
Written by Guest Contributor: Elenore Goode

 

Rusty Blackhaw, Cramp Bark – Viburnum rufidulum
Family: Caprifoliaceae (Honeysuckle)

Fall weather draws beautiful colors from the leaves and berries of the Rusty Blackhaw tree, one of the most common and widespread species of the Viburnum genus in Texas. Rarely growing over 20 feet in height, the berries of this graceful understory tree are an important source of food for wildlife heading into winter. Viburnum rufidulum can tolerate full sun and rockier soils than other Viburnums, but truly loves to grow in the deep, rich soils and shade in the understory of tall forests, the forest edge, and along streams and rivers. They send out bright puffs of white blooms in spring, which are similar to the blooms of other small trees like Roughleaf Dogwood and Elderberry, which are often found in the same areas. This genus is also frequently referred to as Cramp Bark, and the different species have long been used for their medicinal qualities that soothe muscle spasms, such as women’s menstrual cramps, among other uses.

All Images © Elenore Goode 2018
Rusty Blackhaw’s distinct features include its dime-sized oval-shaped berries that change in color from green, to pink, to purple, blue and then dark bluish-black when ripe, its small, toothed, oval leaves that turn a deep red hue in fall, the drooping form of its limbs, the rusty color of the new leaf buds, and the large, rough “dinosaur scales” of its bark. The edible berries are sweet and mild when ripe, and somewhat prune-like once they dry; a nice nibble on the trail. In landscapes where there are not enough fruiting trees present to support wildlife, the berries may disappear as soon as they ripen, or before…but where there are enough berries relative to wildlife and they aren’t immediately eaten, the berries can remain edible on the tree into winter, providing a long-lasting food source.

 

Viburnum rufidulum is one of the many beneficial fruiting trees of the natural hill country forests and prairies that were once present here in great numbers before large-scale habitat destruction occurred. The loss of the vast amount of vegetation that sustained and was managed by the millions of deer, elk, bison, black bears, etc that lived here is still felt by wildlife and plant populations today, as this habitat has never been allowed to fully recover to its historic species diversity and abundance. Like many of the more palatable natives trees (more palatable than Juniper, that is), most Rusty Blackhaw seedlings are currently unable to grow and mature across much of their natural range.
The continued presence of high browsing pressure on a habitat that is already denuded of much of its plants has created a situation where most species of native plants in many parts of the hill country and much of Texas have not been successfully reproducing for anywhere from decades to even 100 years or more. These are any areas where we see old trees, but no new young stands of trees growing up to someday replace the old.

Despite the very small number of livestock and wildlife currently in TX compared to 200 years ago, the vegetation is still unable to recover because livestock have unrestricted constant access to the plants, and there are too few predators left to influence the movement of wild herbivores, many of which are also fed and managed like livestock. The distribution of plants has subsequently shifted towards the spiny, thorny, less palatable species that can withstand this land mismanagement. Many places have a large amount of young junipers constantly coming up because there are few other fruiting trees left for birds and mammals to eat, and so they eat the prolific juniper berries and drop those seeds under every large tree they sit in. And in many places, the only seedlings able to survive browsing once they germinate are also the junipers. Thickets of spiny brush in forests often contain many rare and endangered native plants that manage to remain in the landscape only in such safe and impenetrable areas.

All Images © Elenore Goode 2018
Understory trees and shrubs like Rusty Blackhaw are still locally present and sustaining viable population sizes in some areas, but are also locally extinct from large areas, as has happened to the population distribution of many trees in heavily-browsed and eroded landscapes. Some species, like the Hawthornes/Mayhaws, have become extinct from most of their range in the hill country due to the loss of suitable habitat and soil moisture that comes with erosion and deforestation. The micro-climate conditions these trees thrive in that were once present here – in terms of soil depth, moisture, and canopy cover – can be re-created across their historic range by stopping erosion, slowing and soaking in rainfall runoff, letting forests grow old and create deep shade, and allowing forest organic matter from limbs and leaves to accumulate and build the rich soil these understory trees love.
Re-introducing the great historic diversity of native fruiting trees is also essential to creating the habitat stability necessary for restoring so many other macro and micro wildlife populations above and below ground. When there are more different species growing, then there is a greater amount of time when food is available from their leaves and fruits, reducing the temporal fragmentation of resources in the landscape.

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