What is the exactly "Sal tree" described in the Tripitaka?

Because in last time I wrote the story of Bodhi tree as a part of the Buddha history, I was curious and interesting in the content of this history, which involved a lot of plants occur in Indian peninsula. One of the most important plants in the Buddha history, besides the Bodhi tree, is the Sal tree. Thia plant is connected to both the birth and the death of the Buddha. The Tripitaka informed that Queen Maya (Prince Siddhārtha’s mother) gave birth to him under the Sal tree while grasping its branch during the journey to her hometown. The Buddha then reached nirvana under the couple of Sal trees, too.

The Sal tree has the scientific name as Shorea robusta. The Indian myth told that this plant was born from one of the Indian goddress. She then told human that this plant is the great timber that suits for building house. This might be the origin of the name “Sal” (derived from sala - “house”) came from. Its scientific name also described this property as robusta means strong in Latin.

In Thai-language Tripitaka, Sal tree was translated to be the Rang tree (Shorea siamensis). Unlike Sal tree, this plant is the native species in indochina continent. Their appearance is almost identical, except in the minor detail, for example, the withered leaves of Sal tree are yellow while the Rang tree is red. One possible reason for this confusion between the Sal tree and Rang tree in Thailand might come from the native name of Sal tree in some region in India, which is called Harang tree. The “Harang” sound resemble to Rang in Thai and might cause the misunderstanding that “Harang” is Rang tree.

Another sound-alike plant of Sal tree is the cannonball tree or Couroupita guianensis, the native plant from South Africa continent. In Sri Lanka (and other countries like Indonesia), this plant is called “Sala”, which is sound like Sal tree and some people misunderstand that this plant is the Sal tree in Tripitaka. This misconception was passing through to Thailand, so nowadays you can see the cannonball trees are cultivated in many Thailand’s temples.

From left to right: The flowers of Rang tree, Sal tree and cannonball tree (Pictures from the website of  the Forest Herbarium, Department of National Parks, Wildlife and Plant Conservation, Bangkok, Thailand.)