Unique Features: The Pin Oak, also known as the swamp ‘Spanish’ oak is native to the east central U.S. They are one of the fastest growing oaks and transplant easily because of their shallow root system, unusual for an oak. The dark green leaves have distinct sharp points and very deep sinuses, or indentations, almost reaching the central vein of the leaf.  This tree is intolerant of soil pH above 6.5, and prefers an even lower pH, so a soil test of the planting site is recommended.  High pH soils impede iron uptake, and the result is iron deficiency, or chlorosis. This shows up as a yellowing of the leaves while the veins remain dark green. Since iron is important in the photosynthesis process this causes the tree to languish, and it can eventually fail. Amending with soil sulfur will help lower pH, as will using a pine needle or oak leaf mulch.