Bingo! Ironwood is used the world over for about 30 species from Acacia to Xanthostemon.
The first is actually Carpinus caroliniana. The 'grove' bonsai is C. laxiflora or "Looseflower". That bonsai is at the Longwood Gardens and if you are ever down this way I always have a membership - the whole place is worth seeing, from majestic stands of trees along the trails to the hall of bonsai in the conservatory. The thorny mess is also in a hot room of the conservatory there and is a Pachypodium lamerai from Madagascar - in the Dogbane family.You're up...