((Q. macrocarpa x robur) x lobata) x lobata | Valley Springs
The acorns shown on the previous page are likely from a tree grown from an acorn shown in this photo. In other words, the mom of the acorns in the previous image is likely one of these. The sprouting trays are deep, and have an open lattice on the bottom, to allow air-pruning of the powerful tap roots emerging from these large acorns, packed with hybrid vigor. Air pruning takes advantage of the fact that roots can't grow in air. If a root grows through a soil medium, and then emerges into air, the root tip dies, causing the root to form multiple sprouts, which then themselves grow into the air, die back, and repeat the process, creating a dense root root system that grows well in nursery situations. A key to successfully growing oaks in a nursery setting is to temporarily convert the root system from the natural tap root to a fibrous root system, avoiding problems with circling and girdling of roots in solid-walled containers, and increasing the root surface area for water uptake, speeding the growth of the trees. Pioneer nursery containers are an excellent example of such a system, and have proven highly efficacious in nursery production.