Tag Archives: stomata

Michigan’s Spruces (Picea)

Posted on by
3

Spruces have needles less than 20mm (3/4 inch) long with square cross-sections. They never occur in bunches, just one needle per node. They can be confused with Balsam Fir (Abies balsamea) but Firs have needles with flattened cross-sections. If you can roll a needle in your fingertips then it is a spruce.

Balsam Fir and Spruce Needles and Branchlets

Balsam Fir and Spruce Needles and Branchlets

Michigan has two native spruces, Black Spruce (Picea mariana) and White Spruce (P. glauca). Norway Spruce (P. abies) is now naturalized into the state.

Picea mariana branchlets

Black Spruce Branchlets

Picea mariana pegs and cones

Black Spruce pegs and cones

Black Spruce has needles shorter than 16mm (5/8 inch) and densely pubescent, meaning furry, first year branchlets. The needle bases, which sit on a peg-like projection, are difficult to see. These peg-like projections stick out at 90 degrees to the twig. If cones are present, they are about as wide as they are long. In southern Michigan, Black Spruce grows only in cool bogs. North of Bay City, it will also grow in upland forests and interdunal swales. Even in the north, it prefers a damp habitat and often occurs with Tamarack (Larix laricina) and White Cedar (Thuja occidentalis). The common name refers to the dark needles this tree normally has.

Picea glauca needles and cone

White Spruce needles and cone

White Spruce has needles that are normally longer than 16mm (5/8 inch) and hairless first year branchlets. The needle bases are easily seen. The peg-like projections  point forward at approximately 60 degrees from the twig. Cones are two to three times longer than wide. The tree’s native range is north of West Branch. It grows in similar habitats as Black Spruce but will also thrive in drier locations. The common name refers to the waxy layer on the young needles.

Picea abies needles and cone

Norway Spruce needles and cone

The native range of Norway Spruce is central and northern Europe. It is escaping throughout Michigan. The branchlets droop and its cones are large, approximately 130mm (5 inch) long. Norway Spruce is commonly planted and beginning to escape into natural areas. Its needles are stiff and have rows of minute openings properly called stomata.

Picea abies stomata

Norway Spruce stomata

Copyright 2014 by Donald Drife

Webpage Michigan Nature Guy
Follow MichiganNatureGuy on Facebook

Balsam Fir and Hemlock in Michigan

Posted on by
4
Balsam Fir and Spruce Needles and Branchlets

Balsam Fir and Spruce Needles and Branchlets

Balsam Fir, (Abies balsamea) is a common conifer in northern Michigan. It often grows with Aspen (Populus grandidentata & P. tremuloides), Jack Pine (Pinus banksiana), or Paper Birch (Betula papyrifera). It is also found in White Cedar (Thuja) swamps and bogs. Often the needles form flat branchlets but the needles can encircle a branch, resembling a spruce (Picea) branchlet. When I began to look for spruce trees to photograph I was surprised to find that many of the stands I thought were spruce actually were Balsam Fir with their needles encircling the twigs. Spruces have square needle cross-sections and Balsam Firs have rectangular cross-sections. The needle scar, that is the mark left on the twigs when the needle falls off, is round on the Balsam Fir. Its needles fall and leave a clean branch. Spruces leave rough projections along the branchlets after the needles fall. Balsam Firs tend to hold their dead needles on older branches and spruces shed their needles. Balsam Fir has distinctive pitch filled pockets under the surface of its bark.

Abies balsamea Branchlet and Bark

Balsam Fir Branchlet and Bark

Abies balsamea Balsam Fir Needles

Balsam Fir Needles

Although I spend much of my field time in the range of Balsam Fir, I seldom see it producing cones. Perhaps they are produced at the tops of tall firs and I miss them. The cones fall apart, dehisce is the technical term, while still attached to the branches, so no cones fall to the forest floor. I often see seedling Balsam Firs so they must be producing cones.

Tsuga canadensis Branchlet Stomata Cones

Eastern Hemlock Branchlet, Stomata, and Cones

Eastern Hemlock (Tsuga canadensis) is common north of Bay City and rarer in southern Michigan where it will grow in a protected hollow or ravine. In the north, it will grow with hardwood trees, White Pine, or in pure stands. Hartwick Pines State Park has an elevated, barrier free, “treetop” walkway leading into its Forest Center. The walkway leads through a nice Hemlock and American Beech (Fagus grandifolia) woods. I enjoy walking through the treetops and peering into the canopy. I photographed the Hemlock cones from this platform.

The needles are short, normally less than 13mm (1/2 inch), blunt, with a few teeth toward the tip. They are dark green above and have a white stripe on the lower surface. The white stripe is actually composed of minute openings in the leaf called stomata. These openings allow the plant to “breath.” Hemlocks also have needles that lay on the twig, with their lower surface pointing up. The needles appear to occur in flattened clusters but actually are produced from around the twig. The leaves bend, giving the branch its characteristic flattened look.

Copyright 2013 by Donald Drife

Webpage Michigan Nature Guy
Follow MichiganNatureGuy on Facebook