Sterculia murex: Lowveld chestnut

 

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Interactive Botanical tour

Point No. 2

Species: Sterculia murex Hemsl.

Family: Malvaceae

 

Sterculia murex with common names: lowveld chestnut (English), laeveld kastaiing (Afrikaans), umbhaba (Swazi), mohlatsane (Northern Sotho) is a generally understudied endemic tree with a small distribution in the Mpumalanga escarpments of Legogote Scarp Forest Subtype and some patches in the Kruger National Park preferring loamy soil ⁴.This family contains 243 genera and at least 4225 species of herbs, shrubs, and trees.

This tree was planted here close to the law building to serve as a grove. It was the tree of the year in 2009, facilities usually make a point of planting the tree of the year on their property. This undomesticated African nut tree is often used by the Consumer Science department for recipe development, particularly novel cereal bars made from indigenous nuts.

The genus Sterculia is named after the Roman god Sterculius, the god of manure, referring to the foul smell of some of the flowers in this genus. The species epithet, murex, means spiky parts referring to the spiky fruits enclosing the dark rounded seeds. Even though this tree’s common name is the lowveld chestnut, it is not closely related to the chestnuts at all. The flowers bloom in great abundance between July and September. The bark of the tree turns dark and grooved over time, indicative of its archaic age ².  

Figure 1: Large clusters of waxy flowers forming. Simon Attwood, iNaturalist.

 

This tree species has lobed leaves and can get quite large in canopy structure over time reaching heights of up to 18 meters! This tree blossoms in Spring for roughly two weeks presenting its charming yellow and orange spotted flowers.

Figure 2: The large lobed leaves. Rob Palmer, iNaturalist.

Interesting uses include using the open fruit shell to make a funky ashtray since the shell isn’t easily charred by lighted cigarettes. Botanists grow the tree mostly for decorative purposes since the wood is soft and does not burn long ¹. The ecological use includes sweet, oily seeds fed upon by baboons and monkeys that can also be roasted to be enjoyed by us humans.

Figure 3: The spiky seed capsule with the large and nutrient rich seeds inside. Timmcclurg, iNaturalist.

 

A study done by ³Regnier, and colleagues found that the nuts contain on average 14% protein, has phenolics rich with antioxidants, and has an array of micronutrients like calcium and iron. Roasted Lowveld chestnuts can be incorporated into cereal bars and snacks as a healthy and nutritional snack. There are even talks of domesticating the tree to produce these nuts on a large scale, that’s so cool right!

I hope you all enjoyed the story of this false nutcase of a tree as well as the shade it provides on those scorching hot days!

 

Text prepared by Christiaan Steenekamp and Hanro de Beer, 2022 BOT 366 class.

 

Cited sources:

 

¹Becking, D. (2022), October. Tree sa. Nelspruit, Mpumalanga, South Africa. Retrieved from https://treesa.org/sterculia-murex/

²Butchart, D. (2012). Natuurlewe van suid-afrika. Nelspruit: Struik nature.

³Regnier, T., Kazaz, S., Du Plessis, B., De Jager, K., Augustyn, W., Roux-Van der Merwe, R., & Badenhorst, J. (2017). Quality and safety of Sterculia murex, a scientifically unknown nut from southern africa. South African Journal of Botany, 108: 287-293.

⁴Sampson, J. (2022), October. Growing the lowveld chestnut. South African Smallholder, pp. 13-15.

 

Images:

Simon Attwood, iNaturalist, https://www.inaturalist.org/observations/122983759

Rob Palmer, iNaturalist, https://www.inaturalist.org/observations/147832920

Timmcclurg, iNaturalist, https://www.inaturalist.org/observations/147105041