Paul Bunyan Trail in October

Photographs in this posting show off fall scenery near Walker, Minnesota along the Paul Bunyan Trail, a Rails-to-Trails route between Crow Wing State Park and Bemidji (115 miles). This hilly and remote section of the trail, between highways 34 and 371, runs through the Chippewa National Forest.

Scenic Overlook

Fir and Aspen

Forest Views

Patterns in Conifer Growth

Annual growth is reflected by patterns seen in the branches of conifer trees. Robert Knudson, a local biologist, points this out in a terrific YouTube video about our Northern Minnesota conifers. Pictures in this post illustrate two of the patterns featured in his presentation.

Annual growth of Balsam Fir

The pictures above show buds of a Balsam Fir that are the starting points for next year’s new growth. Note that the buds are in groups of three.

Zooming out, the picture above shows how last year’s group of three buds at a tip of a branch (at the red dot) have grown out to produce three new branches. Each new branch has its own set of three buds at its tip.

Zooming out again, the picture above shows the pattern of annual growth in this Balsam Fir branch. The picture is annotated with alternating red and blue lines to indicate five years growth of this branch.

Annual Growth of Red Pines

Stands of Red Pine are shown in the pictures above. Note that branches are seen at fairly regular intervals along the trunks of the trees. Each interval between levels with branches reflects one year of the tree’s growth. The age of a Red Pine can be roughly estimated by counting the levels with branches along the trunk of the tree.

White and Jack Pines have the same growth pattern, but not as pronounced or regular as seen in Red Pines.

I noticed that this growth pattern is also evident in knotty pine tongue-in-groove panelling. As shown in the photos below knots in the wood are at regular spacings, reflecting yearly growth of the pine trees.

Fall Colors; Why?

Interplay among three pigments is responsible for the changing colors seen in plant leaves each fall.

  1. Chlorophyll — this is the key green compound that enables the plant to convert sunlight and CO2 to sugar throughout the summer.
  2. Carotenoid — a yellow/orange compound that is present in the leaf throughout the year. When green chlorophyll breaks down in the fall leaves can take on the color of carotenoid.
  3. Anthocyanin — a red compound that is usually produced in fall when excess sugar is trapped in the leaf.

In response to longer fall nights, deciduous plants begin withdrawing sugars from their leaves and stop providing leaves with nutrients needed to maintain chlorophyll. The chlorophyll breaks down, which may turn the leaves the yellow color of carotenoid. Alternatively, a leaf may turn red because of anthocyanin created from trapped sugar.

Maple Leaves

Maple leaves with yellow, red, and green colors reflect different proportions of carotenoids, anthocyanin, and chlorophyll.

Hazelnut Bushes

Hazelnut bushes in the two photographs above are directly across an east-west road from each other. The side of the road with the southern, sunny exposure has hazelnut bushes that have turned reddish. The other side with less sun, has bushes that have turned yellow.

The likely reason for the color difference is that leaves with more sun exposure contained more sugar, which transformed to red anthocyanin. Yellow carotenoid has colored the bushes that have had less sun exposure.

Early Meadow-Rue

Color change is not restricted to trees. The image above shows a plant in the buttercup family, Early Meadow Rue, with fall colors. Its leaves with green centers and purple edges likely reflect the distribution of remaining chlorophyll and anthocyanin.

Wildflower Roundup

With fewer wildflowers in fall there is an opportunity to feature interesting flowers previously overlooked.

White Rattlesnake-root (Prenanthes alba)

White rattlesnake-root, also known as White Lettuce, is a shade-loving member of the aster family that flowers in the late summer. The plant pictured was in a wooded section of the Paul Bunyan Trail north of Hackensack Minnesota.

Native Americans used Rattlesnake-root for many medicinal purposes. In particular, the Iroquois used a poultice made from its roots to treat rattlesnake bites. There are also stories that juice from the plant is effective as a rattlesnake repellent.

Birdsfoot Trefoil (Lotus corniculatus)

Birdsfoot Trefoil is a plant in the pea family native to Europe. It has been purposely introduced in North America as a forage plant and as a control for roadside erosion, and is commonly seen blooming in our area from June to August. “Birdsfoot” refers to its seed pods that occur in clusters that resemble a bird’s foot.

While seed for this plant is still offered commercially as a cover crop, the Minnesota DNR considers it an invasive species that should be controlled. Dense mats of it choke out desirable native plants, which is of concern.

Butter and Eggs (Linaria vulgaris)

Butter and Eggs is an invasive species also native to Europe, with flowers similar to snapdragons . Yellow Toadflax is one of its many alternate names. It was brought to America as an ornamental plant, and because it was used to make yellow dye. It has spread aggressively to become an undesirable weed, mildly toxic to livestock.

Mullein (Verbascum thapsus)

Mullein was featured in a previous post, prior to its bloom. That post focused on the utility of its velvety leaves (Nature’s Charmin). But, it also has interesting flowers, as shown in the photo to the left.

Fungus on Trees

Shelf-like fungal growths on trees are known as conks

Fungus identification is best left to experts, but I think the “conks” shown in the pictures above are the species Phellinus Tremulae. The photograph in the upper right is a close-up of the porous bottom-side of one of them. So far I have seen these growths only on the aspen trees locally called “popples”.

Phellinus Tremulae fungus is notorious for causing heartrot, which is the decay of the heartwood of live trees. This weakens trees, and aspens infected with this fungus are susceptible to toppling over in the wind.

Phellinus Igniarius is a very closely related fungus that is usually found on willows. I mention it because of a strange use. Alkaline ash produced by burning this fungus enhances the effects of natural plant alkaloid compounds, like nicotine and caffeine. Alaskan Native Americans mix tobacco with this fungal ash to make a concoction they call “iqmik”. Chewing it provides a dangerously powerful dose of nicotine.

Heartland Trail in September

Photographs in this posting show off fall scenery near Nevis, Minnesota along the Heartland Trail, a Rails-to-Trails trail for biking/running/walking that extends from Park Rapids to Cass Lake (49 miles). Also in our area is the Paul Bunyan Trail, a Rails-to-Trails route between Crow Wing State Park and Bemidji (115 miles).

The Rails-to-Trails Conservancy (RTC) promotes conversion of abandoned rail corridors to bike/running paths across the country. As a frequent user of these paths in Minnesota and other states, I’d like to advocate that people get out and use them. They are tremendous resources, and seem to me to be under-utilized.

Along the Trail

Lake Belle Taine

A very different wildflower

Indian pipe is different from any of the plants previously shown in this blog. It also has the most interesting survival strategy.

Indian Pipe (Monotropa uniflora)

Unlike most plants, Indian Pipe has no chlorophyll and does not depend on the sun. This clump of it was thriving in a deeply shaded forest setting. However it is not a fungus, it is in the Ericaceae family of plants, the same family as blueberries and azaleas.

The Indian Pipe survives as a parasite of the Russulaceae family of fungi in a relation known as mycotropism. Fungi are thought of as parasites of plants, but actually plants and fungi are commonly in a mutually beneficial relationship (mycorrhiza). Fungi receive sugars from the plants and give the plants nutrients that they have liberated by breaking down vegetative debris in soil. Indian Pipes seem truly parasitic though, fungi don’t appear to realize any benefit in return for feeding them.

September Wildflowers

Wildflowers, particularly members of the aster family, are still decorating the roadsides in our area in September.

Asters (genus Symphyotrichum and Eurybia)

Asters are very prevalent along the roadsides here in mid-September. Minnesota has many species of Aster, within the genus Symphyotrichum the Minnesota Wildflower website lists 19! The first two asters shown in the slideshow below have white petals. I believe the first of these shows the Panicle Aster and the second is the Calico Aster. The following four slides are blue/violet asters and there are many species these could be: Lindley’s Aster, Smooth Blue Aster, Large-Leaved Aster, Sky Blue Aster… maybe others too.

Tall Goldenrod (Solidago altissima)

Goldenrod is another very common roadside wildflower here in September. It is actually in the same family as asters (Asteraceae). Like the asters, there are numerous species of Goldenrod, I believe Tall Goldenrod is the one most often seen locally.

Goldenrod is widely believed to cause seasonal allergies, but this is not true. Goldenrod pollen is too heavy to be wind-borne. Ragweed produces wind-blown pollen at the same time that Goldenrod blooms; it is likely responsible for the bad reputation of Goldenrod.

While Goldenrod is generally considered a weed in North America, it is regarded as a desirable garden plant in Europe.

Common Ragweed (Ambrosia artemisiifolia)

Ragweed was mentioned as the true culprit largely responsible for seasonal allergies (not Goldenrod). So, it seems appropriate to show what it looks like.

This picture of Ragweed was taken in July, before it produced its characteristically non-showy flowers. It is very common alongside our gravel roads, but I confess that I did not realize its identity until using the Picture This app…

September Scenery

We took a walk along the Paul Bunyan Trail, north of Hackensack MN, on a gorgeous day in mid September. This post simply intends to share some of the views from along the way.

Sumac turning red among paper birch

Virginia Creeper climbing in a Green Ash

Virginia creeper and its similar species Woodbine are vines that can strangle their ‘hosts’. Also their berries are toxic to humans. In these pictures its red leaves contrast nicely with the yellow leaves of an ash.

White pine towering over yellowing ash and maple

Paper birch, feisty garter snake, and red sumac

Scenic ponds


Mushrooms have appeared in abundance in our area in September. Mushrooms are actually reproductive structures that seasonally sprout from networks of fungal cells in the soil called mycelium. These fungi are critically important in the forest ecosystem as decomposers, soil would not form without them. About 120,000 species of fungus have been identified, however it is estimated that there actually are 2-4 million distinct fungal species. There is much left to be learned in this field!

Definite identification of mushrooms requires expertise and careful examination. All the identifications of mushrooms below are uncertain, specific species are often nearly impossible to distinguish. After struggling to identify the mushrooms pictured below and learning how several mushroom species are deadly poisonous, I certainly will not be tasting any of the specimens I find in the woods!

Genus Amanita (?)

The mushrooms in the pictures above are likely in the genus Amanita. A possible species identification is Amanita vaginata, or the grisette mushroom. If so, the mushroom is not poisonous. However, the Amanita genus include the most deadly poisonous mushrooms, namely Amanita bisporigera, a.k.a the Destroying Angel, and Amanita phalloides, a.k.a. the Death Cap. Mushrooms in the Amanita genus are estimated to have caused 95% of deaths from mushroom poisoning. So, eating any mushroom from this genus is strongly discouraged.

False Chanterelle (?)

Chanterelle are sought-after edible mushrooms, but they can easily be confused with the false chanterelle. I think the mushrooms pictured above are the false chanterelle — a helpful YouTube video describes how to distinguish between the two.

Boletaceae family

Mushrooms in the Boletaceae family, commonly called Boletes, are characterized by pores rather than gills on their undersides. The more common boletes are not poisonous. Like many mushrooms, boletes are mycorrhizal partners with trees. This means that they and trees have a mutually beneficial relationship. The mushroom helps the tree absorb water and nutrients, while the tree provides sugars and amino acids to the mushroom.

Genus Russula (?)

Genus Clitocybe (?)