Yellow Avens is a native erect perennial forb, growing on stout hairy stem from 20 to 40 inches high.
The leaves are lyrately divided with 2 to 6 pairs of leaflets, though usually 3 or less, with both upper and lower surfaces sparsely hairy as are the leaf stalks. Leaflets are unequal with the terminal leaflet the largest and the lateral leaflets smaller but similar in shape; and on the larger basal leaves the additional lateral pairs will be smaller than the first pair. The overall leaf shape is rhombic to circular. Leaflet bases of this species are more tapered as opposed to heart shaped. Leaf margins are coarsely toothed. Upper stem leaves are smaller with the leaflets appearing to be just toothed lobes on the very upper leaves. The leaf stalks end with a pair of ovate leaf-like stipules that also have coarse toothed margins.
The inflorescence is a terminal loosely branched cluster of one to several flowers on long stalks.
The flowers have hairy stalks with a green calyx that has five sepals that have triangular pointed tips and hairy underside surfaces. These reflex when the flower is open. The corolla has five yellow petals broadest in the middle with rounded tips and narrowed bases. These are longer than the sepals. There are numerous stamens with greenish-yellow filaments and reddish-brown anthers. These surround a central green receptacle that is composed of numerous carpels each with a style. These styles are jointed about 1/4 of the distance back from the tip and twisted at that point to form a hook. The base part of the style has very fine hair but not glandular hair.
Seed: At maturity a dry achene is produced that is flattened in shape, longer than wide, with the base part of the style forming a long beak. The hooked end of the style frequently breaks away if not caught on fur or clothing first. Seeds require 60 days of cold stratification for germination.
Habitat: Yellow Avens is found in wet to moist soils of meadows, marshes, woodlands and also at higher elevations in moist woods. It needs sun but will grow in partial shade.
Names: The genus, Geum, is an old Latin name for plants in the Avens group - said to have been used by Pliny in his natural history. The species aleppicum, means 'of Aleppo', the city in Syria. Geum is a world-wide genus and this species is also found in Eurasia. The author name for the plant classification from 1787 - ‘Jacq.’ is for Nikolaus Joseph von Jacquin (1727-1817), Dutch botanist who became Professor of Botany and Chemistry at the University of Vienna where he was also director of the botanical gardens.
Comparisons: There is one other yellow flowered Avens that can be confused with our species here - that is Large-leaf Avens, Geum macrophyllum (photo below). There the base of the styles do not have hair, the leaves have heart-shaped base segments. The White Avens, G. canadense is also similar and when not in flower, one must look to the leaves which are less lobed and the plant overall is less hairy.
Above: The inflorescence is a loosely branched cluster top the stem, each cluster having several flowers. The green calyx that has five triangular sepals that have pointed tips and hairy underside surfaces. These reflex when the flower is open.
Below: The five yellow petals are broadest in the middle. The stamens surround a green receptacle made up of numerous carpels each with a style. The styles are jointed near the tip and twisted there to form a hook.
Below: At the base of each leaf is a pair of ovate leaf-like stipules that also have coarse toothed margins. The base section of the style (2nd photo) has many fine non-glandular hair.
Below- Leaves: The larger lower leaves have several pairs of lateral leaflets and a larger terminal leaflet. Both the upper surface and the lower surface are sparsely hairy.
Below- comparison: The larger leaves with heart-shaped bases of Large-leaf Avens, Geum macrophyllum. Photo ©Emmett J. Judziecwicz, Wisconsin Flora.
Notes: Yellow Avens is not indigenous to the Garden, however it was in the Garden during Curator Martha Crones time as she catalogued in on her 1951 Garden Census as Geum strictum, which is considered an unaccepted name for G. aleppicum. These photographs are from 2009 and 2013 in the Garden wetland. Yellow Avens is widespread in Minnesota, with most county absences being in the drier SW quadrant. In North America it is found in most states of the U.S. except some of the deep south and in Canada it is found in most provinces except Nunavut, Labrador and Newfoundland.
There are six species of Geum, or Avens, found in Minnesota. Besides this species they are G. canadense, White Avens; G. laciniatum, Rough Avens; G. macrophyllum, Large-leaf Avens; G. rivale, Water Avens; and G. triflorum, Prairie Smoke. Most are widespread, except for G. macrophyllum; G. canadense, G. triflorum and G. rivale are also in the Garden.
References: Plant characteristics are generally from sources 1A, 32, W2, W3, W7 & W8 plus others as specifically applied. Distribution principally from W1, W2 and 28C. Planting history generally from 1, 4 & 4a. Other sources by specific reference. See Reference List for details.
Identification booklet for most of the flowering forbs and small flowering shrubs of the Eloise Butler Wildflower Garden. Details Here.
Friends of the Wild Flower Garden, Inc. Text and photos are by G. D. Bebeau unless otherwise credited. "www.friendsofthewildflowergarden.org"