[Hydrangea paniculata f. grandiflora (Siebold) Ohwi, moreHydrangea paniculata subsp. grandiflora Siebold ex Van Houtte, Hydrangea paniculata var. praecox Rehder]
Straggling shrub to 5 m; lvs ovate to elliptic; panicles pyramidal or ovoid, 15-25 cm; pet 5; stamens 10; carpels 2-4; ovary only half-inferior; sterile sep 4, 15 mm, white changing to greenish or bluish in age; seeds linear, minutely caudate; 2n=36, 72. Native of e. Asia, sometimes escaped from cult. in our range. Aug., Sept. A form with all the fls sterile is called peegee hydrangea.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.