Vachellia macracantha aka Porknut

Vachellia macracantha belongs to the pea family, Fabaceae. This woody plant grows as a shrub or tree in tropical America. Kew gives its native range as Mexico to northern Chile. It spans much of the tropical Americas between these points. Older sources use the name Acacia macracantha. Its form varies, which has led to many names. Plants once seen as distinct now fall within this species.

Useful Tropical Plants lists a height of 26 feet [8 metres]. Its main account gives a top height of 33 feet [10 metres]. These figures do not show a clear garden size range. The plant grows in scrub, savannah, and dry woodland. It also grows in fields where plants are coming back. It lives by roads and in forests that shed their leaves. Records range from sea level to about 5,580 feet [1,700 metres].

Kew links the plant to a tropical climate with dry seasons. In the wild, it grows in several kinds of dry forest. These records show where it lives, not tested garden care. The sources give no firm frost limit. Nor do they give a plan for when to water. Useful Tropical Plants says bees and other insects pollinate it. The evidence gives no flower colour or time of bloom. It gives no fruit details, leaf traits, or bark texture.

Root nodules house bacteria that take nitrogen from the air. The tree uses some of this nitrogen to grow. Plants nearby can gain from this process too. Growers plant it with timber trees in tropical South America. Some people grow it to get tannins from its bark. They also cut its wood to use as fuel. In the wild, it can cross with two other species. These are Vachellia cochliacantha and Vachellia pennatula.

Useful Tropical Plants lists no known food uses for this species. Most tested samples could make hydrogen cyanide, which is toxic. Tests found this in 89 percent of samples from Mexico and Central America. The share reached 91 percent in the South American samples tested. The source links this effect to a compound called proacacipetalin. It also notes the use of boiled mature bark in folk care. People have swallowed it or put it on the body. They have used it for eye and kidney complaints. These reports do not prove that such use is safe. Nor do they prove that it works as a treatment.