Leopard Slug in Michigan

 Limax maximus

Leopard Slug

Giant Slug or Leopard Slug (Limax maximus) is a European species now found in North America and Australia. It is in the family Limacidae which is comprised of the keel back slugs. Keel back slugs are longer and thinner than the round back slugs that make up the family Arionidae. Keel back slugs also possess an internal shell under their mantle shield. The mantle shield is the section of the slug closest to their “head.” On the slug’s right side is their respiratory opening.

 Limax maximus

Slug anatomy

 Limax maximus

Front of Leopard Slug

I found Leopard Slugs at the Royal Oak Arboretum behind the Senior Center in Royal Oak, Michigan. They come out when it is getting dark and are active throughout the night. They are 10-15cm (4-6 inches) long. Eating mainly fungus, dead vegetation, and other slugs they are not normally garden pests unless the population is large. I was surprised at how fast they moved. I timed one crossing a 1.5m (6 foot) path in 15 seconds.

 Limax maximus

Leopard Slug at full stretch

For more information on this slug and other gastropods check out Robert Nordsieck’s great website The Living World of Molluscs. The Leopard Slugs are here.

Copyright 2014 by Donald Drife

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Bowl and Doily Weavers

Frontinella communis Web

Bowl and Doily spider webs

I often see the webs of Bowl and Doily Weavers (Frontinella communis) in the shrubs surrounding our cabin near Grayling, Michigan. This spider is also called by the later name of Frontinella pyramitela.

Frontinella  communis Waiting on underside of web

Bowl and Doily spiders waiting on underside of webs

On dewy mornings in late summer and fall the small webs sparkle in the sunlight. A large web is 150mm (6 inches) across and our field can have 50-100 webs. As the common name states the web looks as if it is a woven doily stretched under a bowl. It is one of the most distinctive webs in the Great Lakes Region. The bowl portion of the web collects debris, leaves, twigs, and dust and lasts several weeks. It is repaired but not replaced. The spider hangs from the underside of the bowl. Trip lines span the supporting twigs over the bowl and always look fresh. Insects fly into those lines and then drop onto the sticky bowl. After the spider retrieves its prey it sits on the doily portion to eat.

Frontinella  communis Bowl and Doily Spider

Bowl and Doily spiders up close

After years of seeing these webs I recently found the spider that spins them. It is only 3 or 4mm (3/16 inch) long. The females are slightly larger than the males. This species’ white markings on the abdomen are distinctive. Male and female spiders sometimes share the same web.

I spied a spider on a web about 3m (10 feet) off the ground. After photographing the web I climbed a stepladder to photograph the spider. I normally work with a camera mounted to a tripod and stand on firm ground. I managed to get a few photos and not fall off my perch.

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Michigan Nature Guy

Copyright 2014 by Donald Drife

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Michigan’s Naturalized Teasels

Dipsacus laciniatus

Cut-leaf Teasel

Dipsacus fullonum-habit-white flower-lavender

Wild Teasel habit, white flower, lavender flower


Cut-leaf Teasel habit, flower, seedhead

Michigan has two naturalized species of Teasel: Wild Teasel (Dipsacus fullonum), and Cut-leaf Teasel (Dipsacus laciniatus). Both were originally from Europe but now are found commonly in southern Michigan but rarely in the north. Being tall plants, often 2m [7 feet] high, they are easy to spot along highways. Dried “winter bouquets” sometimes use the attractive heads either naturally or spray-painted. They bloom starting in the center of the head and moving outward toward the top and bottom. Both species are biennials, developing a basal rosette of leaves the first year and flowering in the second.

Dipsacus fullonum leaves

Wild Teasel leaves

Wild Teasel has stem leaves that have entire (smooth) margins but sometimes they have prickly margins or even coarse teeth. The flowers are normally lilac colored but can be white or cream-colored. This species was first collected in Michigan in 1844.

Dipsacus laciniatus leaves

Cut-leaf Teasel leaves

Cut-leaf Teasel is not listed in many wildflower books. Its stem leaves are pinnatifed (with deep lobes) or bipinnatfid (with the lobes, lobed again). Their leaf bases join and sometimes will hold water. The genus name Dipsacus is said to be derived from the Greek word dipsa meaning to thirst, based on this characteristic. This species is taller on average than the Wild Teasel and often forms large colonies. Normally the flowers are a dirty white. The earliest records are from 1894.

Basal rosettes of Dipsacus fullonum-l and D. laciniatus-r

Basal rosettes of Wild Teasel-l and Cut-leaf Teasel-r

Both species are in flower now and easy to find in southern Michigan. Take a close look at teasel and learn to separate the two species. These are impressive plants.

Note: The nomenclature of Teasel is confusing. Dipsacus fullonum was called D. sylvestris and is so-named in older wildflower books. D. fullonum was applied to a European species,now called D. sativus, that has not yet been found in Michigan.
Copyright 2014 by Donald Drife

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Blueberry: a Taste of Summer

Vaccinium augustifolium Flowers and Fruit

Low Sweet Blueberry
Flowers and Fruit

Low Sweet Blueberry (Vaccinium augustifolium) is the common species we see in the sandy uplands near Grayling, Michigan. It has clusters of bell-shaped flowers in June and the fruit ripens in July. The bushes are short, less than 3dm [1 foot] tall and it is hard on my back to bend for hours picking berries. Wild blueberries are smaller but sweeter than their domestic cousins.

Vaccinium augustifolium habit

Low Sweet Blueberry

In years when a hard frost occurs during flowering time or the spring is too dry blueberries yield little if any fruit. Some years the only plants bearing fruit are at the edges of fields that have tall trees surrounding them and protecting the plants from frost. In a dry year, we sometimes find a few berries on bushes growing in a depression that collects some water. In a good berry year, there are acres of fruiting plants. Low Sweet Blueberries are deep-rooted and survive wildfires. The best picking is often two to five years after a burn. Competing plants are gone, sunlight reaches the plants, and the sterile sand is enriched.

Vaccinium augustifolium Fruit showing variations

Low Sweet Blueberry Fruit showing color variations

Vaccinium augustifolium in pail showing fruit color variations

Low Sweet Blueberries in pail showing fruit color variations

Low Sweet Blueberries form a variable species complex. Berries are blue with a solid glaucous bloom, or purple with a gray striped bloom, or shiny black. The leaves are green or glaucous green. The fruit types do not breed true from seed. Shiny black fruit can produce offspring with blue fruit. The extreme plants are distinctive and have been named as separate species or varieties of V. augustifolium but appear to me to be only forms. I know of no pure stands containing only one fruit type. It seems best to treat this as a single variable species.

Vaccinium augustifolium Undersides of leaves

Low Sweet Blueberry Undersides of leaves

Difficulties in classifying this species however do not distract from my pleasure of eating the fruit. A handful of blueberries eaten on a hike is a treat. Blueberry pancakes and pies are a highpoint of my summer. My family has a scale for rating the quality of the blueberry crop. A bad year is when less than a handful is found. Next is a pancake year (1 cup full), a pie year (4 cups), and then an abundant year. In an abundant year, such as this year, you pick enough for pancakes, pies, and to freeze a few for a rare winter treat.

Blueberry Pancakes and Pie

Blueberry Pancakes and Pie

The short bushes are hard to pick from but it is worth the work. Get out while the picking is still good but watch out for bears.
Copyright 2014 by Donald Drife

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