Yellow-Flowered Cinquefoil Is a Popular Garden Plant on Island
By Patricia Martin

This past week I've had several local people ask me about plants with yellow flowers. Midsummer is the time for questions about yellow flowered plants because this is when they are abundant. At least two of the yellow-flowered plants asked about are in the genus Potentilla. You may be familiar with at least one of these plants as in the last few years a shrub in this genus has become very popular as a garden plant, though it may be better known as Cinquefoil.

Cinquefoil refers to the idea that most of the species in the genus Potentilla have leaves composed of five leaflets, though some have seven or more and a couple have only three. The leaves are usually regularly toothed along the margins. All of the members of this genus have five petals that make up the flower and the flowers are usually yellow, though some are white or purple. This genus of plants is in the Rose family and the flowers might remind people of strawberries or raspberries.

As I mentioned, the shrub is probably the most familiar to people here. It is commonly called Shrubby Cinquefoil (Potentilla fruticosa). It is found in the wild at Lone Lake and is planted around many houses in town, including mine. The yellow flowers with five petals are about 3/4-inch wide with rounded petals. The leaves have five, sometimes seven lanceshaped leaflets, which are hairy on both sides. The leaves are alternately arranged along woody twigs and the shrubs are usually one to four feet in height.

Cream, white, and even pink flowered varieties have been developed.

One reason that this shrub has become so popular with people here on Mackinac is that they grow very easily and take little care. This is in part because the Shrubby Cinquefoil loves calcareous soils. In other words, it loves limestone and that is one thing that Mackinac has in abundance.

Another Cinquefoil that is blooming right now and has been mentioned to me is the Sulfur or Rough-fruited Cinquefoil (Potentilla recta). This European native can now be found in areas throughout North America. It was first collected in Michigan in Washtenaw County in 1894 but it is now pretty well established statewide. Roughfruited Cinquefoil is a common weed of roadsides, fields, railroads, clearings, gravel pits, and dry places. On the Island it is found in many of our open areas and I've noticed it particularly near Sugar Loaf.

This herbaceous plant grows one to two feet high and blooms during the summer. The five-petaled flowers of this cinquefoil are pale, delicate, and have a rounded notch at the outer margin. The center of the flower is a darker colored yellow disk. The leaves at the base and on the lower stem are long-stalked and terminate in five to seven long, narrow, toothed leaflets that are hairy above and below. The leaflets that are found higher on the stem are short-stalked or stalkless, are much smaller than the lower ones, and may have only three leaflets. The stems are stout, hairy, and erect.

The final and most asked about Potentilla on Mackinac that I'm going to mention is the Silverweed (Potentilla arserina). It is a prostrate plant which grows in sandy and gravelly shores of lakes and ponds or, occasionally, rivers. It can sometimes be found on rock outcrops, extending to marshy ground, ditches, and roadsides. It is especially found in damp places, often calcareous or even marly areas, and is especially abundant along the Great Lakes shores. On the Island you find it in many places, but it's common along the rocky beaches, though you also find it inland occasionally.

This plant usually has yellow flowers with five petals (though there sometimes can be six or more) up to one inch across on leafless stalks. Each petal and the entire flower are essentially round.

The leaves are what give this plant its common name. They are pinnately compound with seven to many leaflets which are somewhat hairy on the upper surface but with prominent, long, silvery hairs beneath. It is these hairs that give the plant the appearance of silvery leaves (at least on the bottom) and also its name. The margins of the leaves are coarsely and sharply toothed. The leaflets are larger at the terminal end of the leaf and are interspersed with smaller leaflets. These plants often spread by runners that are usually red and have long hair.

The name Potentilla is indicative of the powers attributed to cinquefoil over the years, especially in the Middle Ages. It was believed that these plants possessed strong medicinal powers and were thought to be quite potent, hence the name. A tea made from the leaves of these plants was used as a gargle and mouthwash and was said to cure inflammation of the mouth and gums. Apoultice made from the plant was put on skin wounds. Witches of earlier ages used cinquefoil as a drug, rubbing it over their bodies to produce a trancelike state. The juice of the plant was mixed with such ingredients as deadly night shade, hemlock, thorn apple, and spider's legs to make a variety of potions. It's funny that though these plants were used in witch's brews, they were also used as protection against witches. On a more practical note, there are some records that the juice of cinquefoil mixed with corn makes a good fish bait.

Cinquefoil, in the tradition of flowers, is the symbol of the beloved daughter, because when it rains, the leaves bend over the flower to cover it as a mother would protect a daughter. Actually, this only happens in certain species of Potentilla.

I hope you get out in the woods and along the shore to look for these and other summer, yellow flowering plants. They're in great abundance.

Trish Martin is a year-around resident of Mackinac Island, has earned a master's degree in botany from Central Michigan University, and owns Bogan Lane .