What is the botanical definition of the word “mast”?

Mast is the edible “fruit” of woody plants, like trees and shrubs.

Hard mast is produced by trees, such as the beech, hickory, and oak. Beechnuts, hickory nuts, and acorns have traditionally been used to fatten domesticated pigs. When enough mast has accumulated, the pigs are let loose to feed in the forest. Other hard mast includes the fresh growth of plants on the tips of branches, which wild animals eat.

Soft mast includes berries, drupes, catkins, berries, leaf buds, and rose hips. Drupes are fleshy fruits with hard stones that contain seeds. Apricots, cherries, mangoes, olives, peaches, and plums are examples. Blackberries and raspberries are not berries but aggregate drupes. Catkins are flowers that tend to grow in spikes or cylinders on trees. The word is Dutch for “kitten” because some resemble the tail of a kitten. Birch, hickory, and willow trees, as well as some shrubs, produce them.

Some “masting” species produce seeds at long intervals, while some reproduce using seeds only once before they die. In a “mast year”, a lot more mast than usual is produced. Massive production of seeds in a mast year generates a lot of food for rodents, including stoats (long-tailed weasels) and their distant cousins, rats. A mast year can result in overpopulation of these animals, who were short of food in non-mast years. This type of population explosion can cause these rodents to feed on birds and invade nearby fields in what is known as a “rat flood”.