Types of Oaks

• Oaks fall into two broad categories: red oaks and white oaks. The leaves of red oaks have sharp lobe tips, in contrast to the rounded lobes of white oak leaves. In addition to differences in quality and density of hardwood, red and white oaks differ in acorn types. White oak acorns need only 1 year to reach maturity, but red oak acorns stay on the tree for 2 years. Red oak acorns sprout only if subjected to a long period of winter chill. This stratification period triggers embryonic growth in the acorn the following spring. White oak acorns need no stratification, and if planted they sprout roots the same year they fell from the tree.
  
  

Bitter Acorns

• All acorns contain tannic acid, a chemical also found in oak leaves, bark and wood. High tannic acid content earns oaks a classification as poisonous plants. Toxins in acorns include gallotannins, as well as quercitrin and quercitin. Ingesting unprocessed bitter acorns could cause bloody diarrhea, stomach pain and constipation. The amount of tannic acid in acorns varies with the species. Some varieties of acorn contain low levels of toxins and could be eaten raw. All acorns become edible when processed by grinding and leaching repeatedly in clean water.
  
  

Sweet Acorns

• White oak acorns yield the best nutmeats with the lowest amount of tannin. Two species in North America, the live oak and bur oak, produce acorns that are of higher quality than those of most other white oaks. Evergreen live oaks grow in subtropical North America and bear acorns up to 1 inch long, either singly or in clusters, with up to 5 nuts in a cluster. Acorns of the bur or mossycup oak can reach 2 inches in length. Both types require little or no processing, although to be safe, all acorns should undergo grinding and leaching to remove any bitter flavor.
  
  

Special Varieties

• The quality of the acorn varies with the individual tree as well as with the species of oak. Breeding or grafting superior oaks provides homeowners with the best acorns and fastest-producing oak trees. The maximus bur oak yields the largest acorns of any oak native to North America, according to producer Oikos Tree Crops. Maximus bur oak acorns ripen in late November and weigh up to 2 ounces each, so it usually takes only 8 to 12 of them to equal a pound. Mature kreider bur oaks might produce 500 pounds of low-tannin acorns in one season. Long-lived oak trees often need many years of growth before bearing the first acorn crop, but the ecos bimundors oak bears fruit at only 6 to 10 years old, and at 25 years could bear 25 to 75 pounds of acorns.