Lab 3: Gymnosperms


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Gymnosperms are woody plants that bear seeds. Pollen is produced in male cones (smaller) and the ovules are produced in female cones (what you usually think of when you think “pine cone.”) This is an important group in Northern Wisconsin. There are few enough native gymnosperms in the state that you should be able to master all of them with a little work. Many more species/varieties have been brought in for ornamental or other commercial purposes.

Useful resources for today will be the Field Manual of Michigan Flora (Voss & Reznicek), Michigan Trees (Barnes & Wagner), and the Wisconsin Gymnosperm key

Available here is a color jpg image of all the native genera and families of gymnosperms in the Great Lakes Region.


Pinaceae, the Pine family, diagnostic family characters:

Leaves: Linear or needle-like, spirally arranged, sometimes in fascicles (bundles).
Cones: Female cones with several spirally arranged ovule-bearing scales, each with two ovules. Male cones with spirally arranged microsporophylls (pollen-bearing). Mature cones are often dry and woody.
Habit: Monoecious (separate male and female structures but both borne on the same individual, trees or shrubs.


Plants to key out (and learn):

11. Thuja occidentalis (Cupressaceae) 'Northern white cedar,' 'Eastern arborvitae'
The common name 'arborvitae' is Latin for 'tree of life' because early voyageurs made a tea from the foliage which was high in vitamin C and prevented scurvy. An important food source for deer in the winter. Seedlings and saplings of this species are getting rarer and rarer due to a higher-than-ever deer population in this region.

12. Pinus strobus (Pinaceae) 'White pine'
Another common name for this one is ‘Cork pine’ because it floats so well. One reason why the White Pine forests of the Northwoods of Minnesota, Wisconsin, and Michigan was clear-cut so rapidly in the early 1900s was because of how well this species floated down the rivers. If the loggers had had to haul out the logs using teams of horses they would still be at it. Excellent for construction purposes.

13. Tsuga canadensis (Pinaceae) 'Eastern hemlock'
This Hemlock is different from the one that is poisonous - the poison that Socrates drank was made from a plant from the Apiaceae family. Nevertheless, its bark does contain high concentrations of tannins and was harvested for use in the leather-tanning industry. A favorite food of porcupines. Keep an eye out for the Hemlock on your way out of Birge.

Species to learn:

14. Abies balsamea (Pinaceae) 'Balsam fir'
All true firs have erect female cones. Named 'balsamea' for its scented resin. A popular Christmas tree, and an important component of Boreal forests.

15. Pinus resinosa (Pinaceae) 'Red pine'
One of our most commonly cultivated pines, large plantations can be found in sandier parts of the state. The needles are held in fascicles of two, like Jack pine, but are much longer. Fresh needles break cleanly when snapped.

16. Pinus banksiana (Pinaceae) 'Jack pine'
Named after Sir Joseph Banks, onetime unofficial director of Kew Gardens in London. Its cones are serotinous, meaning that they are tightly glued together with resin and will only open when exposed to the high temperatures of a forest fire, or after several years. Jack Pine forests of a certain age (10- 15 years old) are the only place where the Kirtland’s Warbler, a highly endangered songbird, will nest. Due to this, massive amounts of money and effort have been spent on Jack Pine research and forestry.

Genera to learn:

17. Larix (Pinaceae) 'Tamarack,' 'Larch'
Look out the lab windows to see if you can spot two large Larches.
The only decidous conifer native to Wisconsin. It commonly grows in swamp forests.

18. Juniperus (Cupressaceae) 'Juniper'
The "berries" are used to make Gin, and are relished by birds such as Cedar waxwings. It has fast growing, rot resistant wood. Junipers are considered “weeds” by many farmers and ranchers, who might have them in their pastures, because they are alleged to deplete groundwater.

19. Picea (Pinaceae) 'Spruce'
A Boreal element, similar to Abies in superficial appearance but with needles square in cross section and pointy to the touch. As a general rule of thumb, Fir cones point up, Spruce cones point down. Many spruces have also been brought over from Europe. Black spruce is the usual host of dwarf mistletoe, Arceuthobium pusillum.

20. Taxus (Taxaceae) 'Yew'
The cancer-fighting compound taxol is found in the bark of this genus. The fleshy "fruits" are actually modified cones, these are eaten by birds and spread in their feces. There are several yew shrubberies near Birge Hall. Also due to heavy consumption by deer, the native yew is becoming rarer and rarer in Wisconsin.