According to a recent study (based on the 2010 world population of 6.9 billion) by The Pew Forum, there are: 1  2,173,180,000 Christians (31% of world population), of which 50% are Catholic, 37% Protestant, 12% Orthodox, and 1% other. 2  1,598,510,000 Muslims (23%), of which 87-90% are Sunnis, 10-13% Shia.
Look for the distinctive male Hazelnut flowers, called catkins, which look like 2-inch to 3-inch long yellow or brown growths at the end of the tree branches. The male flowers grow in clusters of two to three and typically form in the winter months. 1  6.
Also called filberts, hazelnuts grow best under full sun. Hazelnut trees (Corylus avellana) are deciduous trees that thrive in U.S. Department of Agriculture plant hardiness zones 4 through 9. The trees have a fast growth rate and reach heights of 15 to 40 feet with a spread of 10 to 12 feet.