Common Name(s): Paperbark Thorn

Synonym(s):

Family: Fabaceae

Native To: Africa

Native Habitat: Wooded grasslands, plains, often along rivers or in floods plains, apparently prefering more mild situations – not in the driest sites.

Growth Habit: Wide-spreading, multi-trunked, flat-topped tree reaching to 45 feet and taller.

Flowering: Mid to late spring months

Distinguishing Characteristics: Deep green feathery foliage, with bi-pinnate leaves to seven inches long. The rachis is pale green and very flexible. In Tucson the tree is deciduous during the later winter months, and re-leafs after spring has begun. Leaves are arranged in alternate formation and are enclosed by stipules at the base. Pairs of white thorns (which can grow as large as three inches long) are arranged along the branches at the nodes, near the leaf bases and stipules. They appear to diminish in length with height. Flowers are clusters of creamy puffballs which have a unique smell. The fruits are typical cylindrical legume pods, rather woody, about 3 inches long. The pods can hang on the tree for nearly a year, and are thick and fuzzy. The bark is unique – layered, papery, exfoliating.

Natural History and Cultivation Notes: Some anthropologists say that humanity’s first and deepest visual imprint of trees are those wide spreading African veldt shapes, dotting miles and miles of open land. The theory is based on knowledge of where humans evolved, of course. But also, there’s a surprising similarity between descriptions that many people have given from dreams – imagining views, under tree canopies, to the horizon.

That iconic tree we all know from the African safari shots, the “branding” of Africa, and from current nature TV programs is Acacia sieberiana or Paperbark Thorn. The species sieberiana was named after Franz Sieber (1789-1844) who was a Bohemian botanist, traveler and plant collector. Woodii is the name given to this particular botanical variety that occurs in east, central and southern Africa and has slightly larger leaflet size.

Matt Johnson, of the Desert Legume Program in Tucson remembers driving through Kruger National Park under a canopy of these wide-spreading trees. He says, “ The highway through part of the Drakenburg had huge, flat-topped, spreading (Acacia sieberiana) trees of variety woodii that stretched across the highway. The canopies were high enough for big trucks to pass beneath them with ease.” The arching canopy attracts several types of birds who build nests and burrow into the trunk, eventually feeding on insects and seeds.

The tree at the University of Arizona in Tucson is situated on the north side of the Cherry Avenue Garage. This is a fairly cold place, and the tree’s trunk and roots remain in shade all winter long. Nonetheless, it seems to be hardy to below freezing.

The University of Arizona’s tree was planted around 1988 from seeds brought to Tucson by Warren Jones. It might be the oldest one in Tucson. It has an expansive canopy that can put on several inches of growth per year. Just now, at about 35 feet, it is beginning to get the balanced, elegant look of the African plains.

Ethnobotany:

Back to UA Arboretum Species Listing Page