Secretion of GH by the pituitary into the bloodstream stimulates the liver to produce another hormone called insulin-like growth factor I (IGF-I). IGF-I is what actually causes tissue growth in the body. High levels of IGF-I, in turn, signal the pituitary to reduce GH production.
Site and Spacing. 1  The pawpaw is a small tree that typically grows to about 20 feet high and less broad. 2  In an orchard setting, tree centers should be at least 10 feet apart. Row widths depend on the size of tractors and equipment -- 20 foot rows may be a minimum width.
DESCRIPTION. Foliage: The dark green, obovate-oblong, drooping leaves grow up to 12 inches long, giving the pawpaw an interesting tropical appearance. The leaves turn yellow and begin to fall in mid-autumn and leaf out again in late spring after the tree has bloomed. Flowers: Dormant, velvety, dark brown flower buds develop in the axils of the previous years' leaves. They produce maroon, upside-down flowers up to 2 inches across.