Characteristics: This flowering deciduous shrub has a rounded form with erect, slender, crayon green twigs. Flowers are yellow and present from May to June. ‘Lena’ is a compact grower somewhat dwarf size. The upper petal of the flower is ruby-red and the two front petals are pale yellow.ark turns dark purplish-gray and fissures into plates. Grows to 4 to 5 feet tall. Zones 6 to 9.