In Sh’mot/Ex. 25:5 (Parshah T’rumah) and elsewhere, the main topic is the preparations for building the Mishkan or “Tabernacle” — G-d’s dwelling place in the world. One of the materials required for building the Mishkan is clearly specified as “acacia wood.” Not just “any” wood or no wood at all.
In Hebrew, acacia wood is called עצי שטים — “atzei Shi’tim;” the “wood of Shi’tim.”
“Shi’tim” was a town or locale. 
Why is acacia wood designated so specifically as the wood to be used in the Mishkan?
It seems like a simple question. But just as in scientific research a seemingly inconsequential detail can uncover mountains of data, small details in Torah can likewise have infinite layers of meaning.
Rabbinic tradition allows for four levels of interpretation or understanding: “p’shat,” “remez,” “d’rash” and “sod.” This post is about “p’shat” — the “plain meaning” of the term. Future posts will cover the others.
 On the “p’shat” level — the level of plain meaning — acacia wood seems to have been mandated because it was plentiful and easily accessible to the B’nai Yisrael during the “wilderness” years, and a material that was known to last:
“This tree grows abundantly in the Sinai peninsula but not farther north. It is a most durable wood.” 
It’s “…darker and harder than oak…avoided by wood- eating insects… common in the Sinai peninsula.” 
Acacias “…flourish in dry soil…” 
“The shi’tah (pl. shi’tim) tree, or acacia…though rare in Israel [proper], is the most common one found in the Sinai. In fact, the name ‘Sinai’ probably derives from the Hebrew ‘seneh,’ a name given to another variety of acacia.” 
“Seneh” or “sneh” is also the Hebrew word used for the bush that Mosheh sees burning without its being consumed by the flames.  Dr. Rittmeyer is connecting “s’neh” with “Sinai.” I’ve also seen “shi’tim” connected with the root-word “shin,” meaning “tooth,” because of the thorns that acacias can have. A midrash connects “sh’tim” with “sh’tut” — “folly.”
“Because of the slow growth of the tree, the wood is hard and dense, therefore heavy. The heartwood of acacia is dark red-brown…due to deposits of metabolic wastes that act as preservatives, rendering the wood unpalatable to insects and resistant to water and fungi.” 
In fact, “acacia” is the name of not only one, but a family of trees: “The genus Acacia contains 750 species, half of which grow in Australia and the Pacific Ocean islands. In Israel there are four species that grow wild and several other domesticated species.” 
We don’t actually know exactly which tree in the acacia family Torah’s indicating. Not all are found in the Sinai, where the B’nai Yisrael were wandering. Some acacias can be more like bushes — which wouldn’t permit their conversion to lumber and planks — while others are more actually tree-like:
“There are about 800 species of acacias. Only a few have a straight trunk suitable for cutting timbers used in construction. These yield hard, durable planks that are lightweight.” 
We can only make a reasonable guess:
“Based on present distribution of acacias in the Sinai, A. Albaida (Faidherbia alba) was the likely source of the wood.” 
One scholar asserts that acacia wood, along with the other materials mentioned in v. 25:5, could have been used while the B’nai Yisrael were wandering:
“Acacia wood…ramskins, lambskins, cloth of goat’s hair, and the like are all manifestations of nomadic existence.” 
We can see that acacia might have been the wood-of-choice because of its natural properties and its availability alone.
We can also speculate that the mandate to use acacia is connected in some way with the bush where Mosheh has his first “vision.” As a reminder, perhaps?
So, even the “p’shat” or plain level of understanding may not always be so easy to define.
Other recommended online articles: http://ww2.odu.edu/~lmusselm/plant/bible/acacia.php and http://www.holylandrestorers.com/trees-of-the-bible/acacia/
For pictures of acacias in their natural setting, and more information about them, see: http://www.treepicturesonline.com/acacia_tree_pictures.html and http://www.holylandrestorers.com/trees-of-the-bible/acacia/
For the discussion of “acacia wood” on the “remez” level, see: https://rabbielimallon.wordpress.com/2013/02/11/2-11-13-acacia-wood-2-remez/ ______________________________________________________________________________  http://en.wikipedia.org/wiki/Abila_%28Peraea%29: “Abila (Arabic: ابيلا) – also, Biblical: Abel-Shittim or Ha-Shittim (or simply Shittim) – was an ancient city east of the Jordan River in Moab, later Peraea, near Livias, about twelve km northeast of the north shore of the Dead Sea; the site is now that of Abil-ez-Zeit, Jordan. Abel-Shittim (Hebrew meaning “Meadow of the Acacias”), is found only in Num. xxxiii.49; but Ha-Shittim (Hebrew meaning “The Acacias”), evidently the same place, is mentioned in Num. xxv.1, Josh. iii.1, and Micah, vi.5. It was the forty-second encampment of the Israelites and the final headquarters of Joshua before he crossed the Jordan. Josephus states that there was in his time a town, Abila, full of palm trees, at a distance of sixty stadia from the Jordan, and describes it as the spot where Moses delivered the exhortations of Deuteronomy. There is to this day an acacia grove not far from the place, although the palms mentioned by Josephus are no longer there.””
 image from: http://search.yahoo.com/search?fr=mcafee&p=acacia+wood+pictures. The planks, although floorboards, are notched and fitted the way that the wall-planks in the Mishkan are described to have been.
 Hertz, Rabbi Joseph I.; Pentateuch and Haftarahs (text and commentary); on Sh./Ex. 25:5, p. 326
 NIV (New International Version) Bible (text and commentary); on Ex. 25:5; p. 123
 ibid. on Yoel/Joel 3:18; p. 1344
 Ritmeyer, Leen and Kathleen; From Sinai to Jerusalem; p. 11
 See Sh’mot/Ex. 3:2
 Musselman, Lytton John; Figs, Dates, Laurel and Myrrh: Plants of Bible and the Quran; Timber Press, © 2007; p. 38
 Etz Hayim (Torah and Commentary); Rabbinical Assembly (Conservative), © 2001; p. 487 (on 25:5)
 ibid. p. 40
 H.M. Orlinsky, quoted in Plaut, W. Gunther; The Torah: A Modern Commentary; Union for Reform Judaism Press, © 2006; p. 553 (H. M. Orlinsky headed a committee of American Jewish scholars who prepared a modern-English version of the Pentateuch in 1963 under the name, The Torah: The Five Books of Moses, published by the Jewish Publication Society of America.)