R. D. Meikle, Flora of Cyprus 1. 1977R. Jahn & P. Schönfelder, Exkursionsflora für Kreta. 1995
but modified
1Small shrub, prostrate or ascending, usually less than 0.5 m high; spines up to 50 mm long; fruit 25-50 mm long, with flattish navel
1'Robust shrub, often with stem, usually 2-5 m high; spines lacking or rarely 1-2, up to 15 mm long; fruit 60-100 mm long, with concave navel