By 1812 Johann Jacob Paul Moldenhawer had shown that plant tissue was composed of independent cells, and in 1826 Henri Milne-Edwards determined that all animal tissues were formed from globules. From time immemorial, humans have enjoyed the medicinal advantages of many species of shrubs. An extract derived from the bark of willows, called salicin, is the active ingredient in one of the most important and useful of all household drugs: aspirin. The distilled liquid from the bark of witch hazel is sold as a skin ointment. A soothing ointment is made of the oil of teaberry. Tannic acid, used for tanning leather and for medicinal purposes, was for many years obtained from the fruits of native sumacs.
The barberries (Berberis) are a worldwide group of deciduous shrubs best known for their thorns and bright red berries. They have yellow wood and simple alternate or whorled leaves clustered on short spurs. Barberries were very popular landscape ornamentals, but their reputation and use drastically decreased when they were found to be the alternate host for the black stem rust, a fungus that infects wheat. The use of hybrid varieties eliminates this ecological problem, and the barberries have once again become common as interesting and colorful ornamentals that provide good hedges, ground covers, and living barriers. The bright red leaves make them an attractive fall shrub, while the persistent, bright red berries attractively color a yardscape through the winter months. The berries are also an important wildlife food used by a variety of birds and small mammals through the winter months.