A prickly customer, this is known to me as cockspur. It grows like an upright bush to a height from where it can hook onto branches etc with its long thorns to gain greater height. It sprawls outwards in search of more branches to elevate from. The younger leaves on a young plant (photos # & 4) appear rounder than more mature leaves. I have only seen thse in this local over the past 20 years or so, but not before.