rachos, = a thorn-bush, briar, a thorn-hedge; a thorn-stick, a twig;
rhach-, rach-, = pertaining to the main axis, spine or backbone;
carpos, = fruit. (LS, BL)
purpura, = purple colour, purple;
-ascens, = indicates process of becoming, hence not fully achieved resemblance, often expressed by the termination ‘-ish’.
purpurasco, = to grow purple, become a purple colour. (ld, BL)