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Fabaceae Acacia tortilis Research Text

  • Writer: Ava Lee
    Ava Lee
  • Mar 10, 2025
  • 2 min read

Updated: Apr 14, 2025


Plant.  Fabaceae Acacia tortilis


Name: Fabaceae Acacia tortilis (umbrella thorn)

Family: Fabaceae

Date & Location: Nashobio, Kenya, February, 2025



Why I chose this plant: I initially was curious as to why I often observed  fabaceae acacia t on the Maasai Mara conservation intertwining. 


Scientific question: How has the Fabaceae adapted to maximize survival by intertwining (circumuntation)? 


The Acacia tortilis belong to the second largest family of the flowering plants, the Fabaceae (Leguminosae); they can be found in various habitats from subtropical biomes in China to grasslands in Kenya. The Acacia tortilis thrive in arid and semi-arid climates, such as Kenya. They feature deep roots, allowing access to water far beneath the surface; minimal leaf surfaces, to limit energy use; and thorns, a defensive mechanism against herbivores. The tortilis, along with the Fabaceae family, exhibits a pronounced DNA found (known as auxin, a hormone) in all plant species that results in a spiral growth (circumnutation) during primary growth.


Circumnutation is the result of  unequal growth rates on different sides of an organ; the side experiencing faster growth causes the organ’s apex to bend toward the side with slower growth, causing a spiral effect (NameThatPlant.net, 2022). The hormone auxin can create different growth rates and is influenced by the internal oscillator (Batista-Silva et al., 2024). And the spiral growth movement can also be caused by the pulvinus, which expands or contracts at the top and bottom.  (Migliaccio et al., 2013). 


The Fabaceae Acacia tortilis responds to external stimuli such as light (phototropism), during its primary phase and develops mechanisms for stability against the winds in the grasslands. A notable example of a species in the Fabaceae family reacting to external stimuli are the rococo beans (phaseolus vulgaris or most commonly known as cranberry beans), which are a staple in Kenya. These beans can be grown in two main forms: climbing (relying on an external support structure) and bush types (Melindamyers.com, 2025). While inner oscillator (a plant's internal clock like humans circadian rhythms) and gravitropism are essential for primary and secondary growth, they do not directly impact circumnutation, however gravitropism can affect circumnutation (Migliaccio, Tassone, & Fortunati, 2013).


Reference List:

Batista-Silva, W., de, J., Joao Antônio Siqueira, Martins, A. O., Ribeiro, D. M., Adriano Nunes-Nesi, Zsögön, A., & Araújo, W. L. (2024). Auxin metabolism and the modulation of plant growth. Environmental and Experimental Botany, 105917–105917. https://doi.org/10.1016/j.envexpbot.2024.105917

Migliaccio, F., Tassone, P., & Fortunati, A. (2013). Circumnutation as an autonomous root movement in plants. American Journal of Botany, 100(1), 4–13. https://doi.org/10.3732/ajb.1200314

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