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.
Floridaâs pawpaws tend to be shrubs, if not dwarfs. They are: Asimina obovata, Asimina incana, Asimina reticulata, Asimina longifolia, Asimina pygmaea, and Asimina tetramera. Farther north one can find the Asimina triloba reaching small tree height and in the coastal areas Asimina parviflora.