Conifers

Conifers are one member of a group of plants known as gymnosperms, meaning ‘naked seeds’, a reference to the seed not being enclosed in an ovary or fruit.  These plants do not flower, but have both male and female cones.  The male cones carry pollen, which is dispersed by the wind.  The female cones that come in contact with the blowing pollen will take some into the ova and produce seeds in the cone.   Cones are green as they grow, turning brown as the seeds mature.  When cones open, seeds are dispersed by falling to the ground or being picked up and moved by animals.  In some conifer species, cones will not open until certain environmental conditions are met, namely the presence of fire.  These species have serotinous cones, ones that only open when exposed to high heat.  Fire also kills other plants that compete with conifers for resources such as sunlight and water, and it releases minerals from burned plants into the soil providing nutrients for new conifer seedlings. 

Most conifers are evergreen, although a few are deciduous.  Deciduous trees lose their leaves all at the same time, when temperatures start to drop in autumn.  Evergreens also lose their needles, a few at a time throughout the year, and they are quickly replaced by new growth so the tree is never bare.  Evergreen needles are thin leaves found on several types of conifer including fir, spruce, and pine.  Other types of conifers like juniper, cypress and cedar, have soft, scale-like needles.  An examination of the needles is the best way to identify a conifer species.  Whether they are stiff and sharp, or flexible and soft; bunched in groups or growing singly; and the number of needles that are in each bundle will help you to identify a specific tree species.

Climate conditions, especially temperature and precipitation, greatly influence the tree species found in any one area.  Colder temperatures reduce the ability of plants to function.  Deciduous plants handle this change by entering a state of dormancy until warmer temperatures arrive in spring.  Precipitation in northern Illinois is generally well distributed throughout the year, although in winter, it falls as snow.  Combined with a frozen soil layer, this water is not available for ready use by any plant species until the spring thaw.  Evergreen species are well equipped to handle these conditions.  Needles have a waxy, outer covering, while roots and stems are filled with resin, a chemical that acts as antifreeze.  The general shape of the tree, with branches sloping down and out, keeps snow from accumulating and freezing on the foliage.  The plants can survive very cold temperatures without damage and are able to start photosynthesizing food as soon as liquid water is available in spring.  This gives evergreen species a jump on shorter growing seasons in cooler northern climates.

Conifers in this area are used extensively by birds, mammals and insects for food and shelter.  They make good habitat, providing protection from wind, rain and flying predators.  A wide variety of insects call conifers home including spider mites, aphids, bark beetles and various caterpillars.  Many of these insect species provide food for woodpeckers and nuthatches.  Squirrel nests are well screened from wind and precipitation by evergreen boughs.  During the day, many bird species like to browse among the ground litter of pine needles and fallen food.  And later in the evening, that same activity is taken up by several mammals prowling the night time.

There are about 700 conifer species found world-wide, and they can be found in backyards, city parks and nature areas all over DuPage County.  They are most abundant in cooler climates and are important timber trees.  All are softwoods, a versatile building material for mouldings, windows, flooring, paneling and plywood.  They provide great backyard habitat in our area, and serve as an important natural resource for many over-wintering species in DuPage County.