"I keep only a small stock for those witches or wizards of sufficient subtlety, for acacia is not suited to what is commonly known as 'bangs-and-smells' magic."
-- Mr. Ollivander (Pm)
Acacia is a type of wand wood known for creating “tricky wands,” described by Ollivander in his essays on wandlore (Pm).
Acacia might be subtle enough for potions work, according to Mr. Ollivander.
The name comes from the Greek akis; "thorn".
Some Acacia species are valuable as timber, such as A. melanoxylon (blackwood) from Australia, which attains a great size; its wood is used for furniture, and takes a high polish; and A. omalophylla (myall wood, also Australian), which yields a fragrant timber used for ornaments. A. seyal is thought to be the shittah-tree of the Bible, which supplied shittim-wood. According to the Book of Exodus, this was used in the construction of the Ark of the Covenant. A. koa from the Hawaiian Islands and A. heterophylla from Réunion are both excellent timber trees. Depending on abundance and regional culture, some Acacia species (e.g. A. fumosa) are traditionally used locally as firewoods. It is also used to make homes for different animals.
From the Web
"Wand Woods" on Pottermore
"Acacia" on the Harry Potter Wiki