Sean Bradley, staff 

In fall, many plants produce and drop fruits to spread seeds and ensure regeneration for next year. There are some of these native fruit-producing plants on campus.

In botanical terms, a fruit is a mature, ripened ovary (reproductive structure of a flowering plant). The ovary’s purpose is to enclose and protect the ovules until the ovules fertilize and turn into seeds. All fruits have a pericarp (the part of the fruit that surrounds the seeds) with three layers, including an exocarp (outermost layer), a mesocarp (middle layer) and an endocarp (innermost layer). While there are three main types of fruit, including simple, aggregate and multiple, we’ll only look at simple fruits since most of the native fall fruits on campus are in this group. Simple fruits are fruits formed from flowers with one carpel or multiple carpels fused together so that it looks like just one carpel; and they can be fleshy or dry. Three types of simple fruits found on campus are drupes, berries and nuts.

Drupes derive from one carpel and typically have one or two seeds. The exocarp is a thin skin, the mesocarp may be fleshy, and the endocarp is hard and contains the seeds. One native drupe found on campus comes from the flowering dogwood. Dogwood drupes come in clusters of two to ten and turn red when ripe. Despite being inedible, the fruits are an important food source for songbirds because they’re rich in calcium and fats. Another native drupe found on campus comes from the black walnut. Black walnut fruits have a fleshy, brownish-green husk when ripe. Inside the husk is a hard, brown, corrugated seed shell (nut) containing a light brown, edible kernel. The kernels are enjoyed by both people and wildlife.

The next type of simple fruit we’ll look at are berries. Berries consist of a fleshy pericarp, one carpel or multiple fused carpels, and many seeds. A native fall berry found on campus comes from an herbaceous perennial called American pokeweed. Growing up to three meters tall, pokeweed has round, alternate leaves on a purplish stem. The berries are purplish-black when ripe and grow on hanging clusters. Despite being poisonous to humans, the berries are enjoyed by songbirds.

The last type of simple fruit we’ll look at are nuts. True nuts are dry, indehiscent (meaning the seeds are retained in the dried pericarp), one-seeded fruits with hard exocarps. Acorns, which come from oak trees, are an example of a true nut found on campus. Every two to five years, oaks produce high yields of acorns in what are called “mast years”. While the exact reasons for masting are unknown, it is believed to have an evolutionary benefit of ensuring future offspring. Lastly, not only are they important for feeding native birds and mammals, but acorns are also edible but must be leached of tannins (a bitter plant compound that’s harmful when consumed in high amounts) and properly cooked before consuming.