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Seeds (What Time is it in Nature)

December 13, 2014

Most of the leaves have fallen from the Prairie Ridge trees at this point and have entered their comparatively dull, leafless stage for the winter. While you might not get to see many leaves on the trees for a while, there are still interesting things going on with a lot of the plants! Many trees produce their seeds in the summer and release them in the fall, so there are seeds everywhere. Looking for seeds can be a great way to see a lot of the interesting shapes and textures that allow our trees to reproduce. Today, let’s take a look at some of the many types of seeds you can find on the grounds!

There are several different styles of tree seeds in the world, but one of the styles that lots of people are familiar with are the samaras. You may have called these “helicopter seeds” or something similar at some point in your life. Trees in the maple group are the best known samara seed bearing trees, including this Box Elder:

Box elder seed

Samaras flutter down slowly from the trees when they fall off, spinning as they go. Winds can blow them a little way so that the trees can spread, but others fall near the parent tree. Many of these will eventually grow new trees where they fall.

Some seeds are kept safe inside a sort of protective case. You are probably familiar with at least one type of tree with this system, such as this pines:

Pine cone

Pine cones start off as compact, dense cones with the seeds developing safely inside. When the seeds have matured and are ready to germinate, the cones begin to expand and the cone scales spread apart, exposing the seeds in the center to the environment. The seeds either fall out of the cones or are moved around by animals, such as squirrels, that gather the seeds from the cones and bury them in other locations. However, pine trees aren’t the only types of trees that keep their seeds hidden inside a sort of case. You may be familiar with these:

sweetgum ball

Sweetgums develop many large green, spiky fruits in the summer and the seeds develop inside. In the fall, the fruits dry out and small holes appear along the surface that allow the seeds to fall from the pods. While you may have a hard time finding the actual seeds of the Sweetgum, you can certainly find a lot of the seed pods, the “gum balls,” along the Prairie Ridge Forest Trail.

Some seeds grow in very dense clusters that either open or break apart to release the individual seeds they contain. The Tulip Poplar has an interesting structure:

Tulip poplar seeds

The fruits grow high up in the trees in the summer in dense, compact clusters. Each fruit contains many seeds, packed together tightly within the fruit. When the seeds mature and the fruit begins to dry out, the seeds begin to spread apart, forming the sort of flower-shaped clusters you can see in the photo. The long, slender individual seeds (the “petals” in the photo above) eventually dislodged themselves from the base of the fruit and fall to the ground.

Many of the seeds we’ve looked at already fall from the tree and, if all goes well and the seed isn’t eaten by something, will grow where it falls. Other trees and shrubs depend on animals (often birds or mammals) to disperse their seeds so that the seeds don’t all grow in one place. Many of these trees offer the animals they depend on for dispersal a tasty treat, a fruit, in exchange for moving their seeds to another location. One example is this Viburnum species:

Viburnum berries

As the fruit passes through the animal’s digestive system, the edible parts are digested and absorbed by the animal and the inedible parts, including the seeds, are expelled in the animal’s droppings. Typically the seeds are moved some distance from the parent tree so that the tree or shrub is able to spread its offspring to new areas. There are lots of fruits still visible on the Prairie Ridge grounds, including American Beautyberry, American Holly, Poison Ivy, Persimmon, and the subject of next week’s What Time is it in Nature, Winterberry.

The Prairie Ridge Forest Trail is a great place to look for seeds at this time of year! You may see seeds on the black top along the paved portion of the trail, but if you take a moment to look you’ll see seeds littered everywhere under the trees. I encourage you to pick up a samara, toss it in the air, and watch it “helicopter” back down to the grounds or shake a few gum balls to see if there are any seeds still inside. Wander down to the shrubs near the bird feeders and you’ll see dozens of bird species feasting on Viburnum and American Beautyberry berries. You may even see a squirrel gathering seeds and burying them in the ground, saving them for later in the winter when other food sources become scarce. There are many interesting seed textures and shapes, so be sure to look out for some on your next visit!

What Time is it in Nature is a weekly feature highlighting the current plants, animals, and other wildlife at the Museum’s public outdoor facility, Prairie Ridge Ecostation. Find out more about the natural happenings at Prairie Ridge at our What Time is it in Nature Archive!

(Photo by Chris Goforth)

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