JARS Volume 26, Number 3: July 1972 articles including the article by Dr. Tor G. Nitzelius "http://scholar.lib.vt.edu/ejournals/JARS/v26n3/"
R. brachycarpum ssp. tigerstedtii is a tall shrub (5 m and taller) or small tree. Young shoots are 1 cm thick (Japanese ssp. about 0.7 cm) and scarcely covered with radiate hairs. The leaves are 15-25 cm long and 5-9 cm broad (Japanese from 7-15 cm long and 3-7 cm broad), covered below with radiate hairs. Flowering is normally 2-3 weeks earlier than in ssp. brachycarpum. Flowers white with greenish spots, 7 cm broad (Japanese ssp. about 5 cm.). Calyx flat, cup-shaped, with distinctive half incised lobes, about one month after anthesis. Pedicels of capsule 3-5 cm long (ssp. brachycarpum has a somewhat smaller cuneate calyx with indistinct lobes and with pedicels only 2-3 cm long). Seeds are much alike in both subspecies. JARS 26(3)