Albizia julibrissin (Willd.) Durazz., family Leguminosae. Persian Acacia, Silk Tree or Pink Siris A native to western Asia now commonly planted as a shade tree in Europe and China, in areas where it can be unaffected by severe frost. In Britain it is most commonly planted as an annual bedding plant, being destroyed or taken into a greenhouse in winter. Height may reach 12m (40ft). The brightly coloured flowers open in July and August, their long pink stamens giving the appearance of a soft brush. The seed pod is 7.5-l5cm (3-6in) long constricted between each seed. Zone 7.