Tag Archives: Rhamnus alnifolia

Our Native Buckthorn

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Rhamnus alnifolia

Alder-leaved Buckthorn

Michigan has a native Buckthorn, Alder-leaved Buckthorn (Rhamnus alnifolia).  It normally grows in fens and is seldom found in dry habitats. It is similar to the invasive Common Buckthorn (R. cathartica) but the two species are easy to tell apart.

Rhamnus alnifolia

Alder-leaved Buckthorn showing stipules and leaf characters

Alder-leaved Buckthorn is normally shorter than 1m [3 feet] tall. Its toothed leaves are strictly alternate with 5 to 9 veins per side and are more pointed at the tips than Common Buckthorn. The leaves have stipules at the base of the petioles; however, they are sometimes missing late in the growing season. The flowers lack petals. The petal-like structures are sepals. Sepals are the covering of flower buds; petals are found inside the bud. There are 5 sepals and 5 stamens on each flower. The flowers, and hence the fruits, are in small groups, less than 3 in a cluster.

Rhamnus alnifolia

Alder-leaved Buckthorn flowers, immature fruit, and ripe fruit

Common Buckthorn can reach the size of a small tree. Its toothed leaves can vary from alternate, to sub-opposite, to opposite, on the same branch. Its flowers are 4-parted with both sepals and petals. Flower and fruit clusters are large, seldom as few as 3in a cluster. The branch tips are normally spine tipped and spines can often be found on the along the main trunk.

Glossy Buckthorn (Frangula alnus) is a wetland invasive species but has non-toothed leaves. Its veins are 6 to 9 per side. It has 5 sepals and 5 petals on each flower. The leaf buds are tan pubescent (covered with dense short hairs).

If you are removing invasive buckthorn you should know this native species. One site in Oakland County was almost destroyed by over-zealous invasive species hunters who did not realize that the invasive Common Buckthorn did not grow into the fen at the bottom of the hill.
Copyright 2016 by Donald Drife

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A Visit to a Fen

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Fens are fascinating. They are sedge peat areas with little, if any, standing water. Groundwater flows through a peat layer that is close to the surface. Less acid than a sphagnum bog, fens host a different community of plants and animals. Unfortunately, Glossy Buckthorn is invading many of our southeast Michigan fens. Recently we checked on a favorite fen, looking for invasive species. Thankfully, none were found but we had a reason to explore the fen for several hours.

Cambarus polychromatus

Paintedhand Mudbug

Walking into the fen on a narrow trail Joyce came across a crayfish. It stood defiantly in the center of the trail, reared up on its tail, pincers waving, antennae flexing through the air. Joyce got her walking stick too close and the crayfish lunged at it. Joyce stepped over him and the crayfish spun to face me. I felt as if I was Tolkien’s Balrog facing a mini lobster Gandolf. “You cannot pass.” [Note: It is only in the movie that he says, “You shall not pass.”] As I stepped over him, he charged my boot. I looked back and he was still guarding his path.

Physocarpus opulifolius

Ninebark

Ninebark (Physocarpus opulifolius) flowered along the trail holding some of its flower clusters at shoulder height. Five-petaled flowers, lobed sepals united at their bases to form a calyx tube, and its many stamens tell me that this is a member of the Rose Family (Rosaceae). Half spherical clusters of white to pinkish flowers with petals dotted in black result in this being one of our showier native shrubs. Its exfoliating (separating into layers) bark is said to give rise to the common name although I have never seen one with nine layers. Another explanation is that it is a corruption of the German word “nein” meaning no. “No bark” better explains the look of this plant.

Cypripedium reginae

Showy Lady-slipper group with last years seed capsules L Closeup of flowers R

A Showy Lady-slipper (Cypripedium reginae) blossomed under a Ninebark. It is our largest native orchid and this plant stood 2 feet (.6m) tall. A pair of flowers topped the plant; one at its prime, emitting a faint vanilla scent, and the other fading. We saw approximately 150 plants. A few Lady-slippers were past flowering, 50 non-blooming, 50 flowering, and 40 in bud. It is a healthy population.

Rhamnus alnifolia

Alder-leaf Buckthorn

Rhamnus-alnifolia

Alder-leaf Buckthorn showing fruit and flower

Our native Buckthorn, Alder-leaf Buckthorn (Rhamnus alnifolia) grew in two small colonies, one with three stems and the other with six. Alder-leaf Buckthorn seldom forms large stands and is not invasive like Glossy or European Buckthorn is. Toothed, strictly alternate leaves, with branches never tipped with spines, characterize Alder-leaf Buckthorn. This plant is seldom over 3 feet (1m) tall. I have seen plants cut and poisoned by over-zealous invasive species hunters. Anyone working to eradicate our invasive Buckthorns should learn to distinguish this native species.

Toxicodendron vernix

Poison Sumac

Poison Sumac (Toxicodendron vernix) flowered in a low, wetter, section of the fen. Shiny leaflets, red petioles, and gray bark are characters of this tall shrub. Urushiol oil, the same oil as Poison Ivy has, is found in all parts of the plant and many people are allergic to it.

Fens are delicate environments and require monitoring for invasive threats. Monitoring provides a great excuse to spend a few hours poking around outdoors.

I later learned that Michigan has eight to ten species of crayfish and this one is a native named Paintedhand Mudbug (Cambarus polychromatus). Crayfish Ontario, part of the Bishops Mills Natural History Centre has a nice guide for Crayfish identification. Mael Glon from Ohio State University corrected an earlier misidentification of this crayfish. Checkout his Crayfishes of Michigan page. Thanks Mael.
Copyright 2015 by Donald Drife

Revised March 2018

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