The 505 leaves collected with one leaf per plant from Platanus acerifolia (Ait.) Willd. were measured. Two new phenomena were found: Firstly, angles between principal veins of three major lobes from the plant indicated the "recessive" golden number". It was meant that golden number was showed by trigonometric function (values were -0.618 and 0.382); Secondly, angle of 60° between principal veins of three major lobes from the plant was a manifestation of taking the shortest path to transport moisture and nutrient, meanwhile this angle was a kind of the Steiner tree structure. Statistical analysis showed angles between principal veins of three major lobes of the plant containing recessive golden number were 31.72°, 38.18°, 51.86°and 67.55°, respectively. The amount of angles including 31.72°, 38.18°, 51.86° and 67.55°, were accounted for 60.69% of all collected leaves. And the percent of angle with 60° was 34.85% of all samples. Thus the amount of angles containing "recessive" golden number and presenting the Steiner tree structure was calculated for 95.54% in the whole samples. The new findings of angles between principal veins of three major lobes of P. acerifolia (Ait.) Willd. are very beneficial for people to deeply understandthe plant architecture.