silverweed

not listed

N3N5 - Vulnerable to Secure

SNR - Unranked

not listed

FACW - Facultative wetland

FACW - Facultative wetland

FACW - Facultative wetland

Silverweed is a 2″ to 8″ tall, ascending to erect, perennial forb that rises on basal leaves from a narrow, often branched taproot.

It first appears as a dense cluster (rosette) of basal leaves. Soon it produces one or more above-ground, creeping, widely spreading runners (stolons).

Basal leaves are inversely lance-shaped in outline (widest toward the tip), up to 10″ long, and up to 4″ wide, rarely longer and usually much smaller. They are on 1″ to 10″ long leaf stalks. Each leaf is pinnately divided into 5 to 31 primary leaflets which often alternate with much smaller secondary leaflets. The leaf axis (rachis) is light green and covered with long, soft, shaggy, sometimes spreading hairs.

The leaflets are oblong or inversely egg-shaped. The larger leaflets are up to 2″ long and ¾″ wide, sometimes larger. The lower leaflets are much smaller. The upper surface is green and may be hairless or covered with long, silky, somewhat appressed hairs. The lower surface is white. It is densely covered with short, white, matted or tangled hairs, and moderately to densely covered with long silky hairs. The margins are deeply toothed with sharp, forward pointing teeth. There are usually 5 to 8, but as many as 11 or more teeth per side.

The stolons are 12″ to 36″ long with leafy nodes every 4″ to 6″ long. Node leaves are similar to basal leave but smaller. Stolons are red and are covered with long, soft, shaggy, sometimes spreading hairs. They send down roots from the nodes which often creates new plants.

The inflorescence is a single flower rising from a stolon node on an ascending to erect, hairy, 2″ to 6″ long stalk (pedicel).

The flowers are ⅜″ to ¾″ in diameter. There are 5 modified leaves (epicalyx bractlets), 5 sepals, 5 petals, 20 to 25 stamens, and 20 to 200 or more pistils. The epicalyx bractlets are green, narrowly to broadly egg-shaped to triangular, often toothed, and about the same size as the sepals. They alternate with the sepals and are hidden below the petals when the flower is viewed from above. The sepals are ⅛″ to ⅜″ long and are densely covered with whitish, silky hairs. The petals are yellow, inversely egg-shaped or oval, 3 ⁄16″ to ⅝″ long or longer, and ⅛″ to ⅜″ wide. The petals are longer than the sepals. The stamens have yellow, 1 ⁄16″ to ⅛″ long filaments and yellow anthers.

The fruit is a 1 ⁄16″ long seed capsule (achene) with a groove on the upper (dorsal) surface.

2″ to 8″

Yellow

Silvery cinquefoil (Potentilla argentea) leaves are palmately divided into 5 leaflets.

Moist to wet. Meadows, marshes, beaches, lakeshores, streambanks, mowed paths. Full sun. Sandy or gravelly soils.

May to September

Sources

2, 3, 4, 5, 7, 28, 29, 30.

Native

Common

Genus
Silverweed was previously placed within the Anserina/Pentaphylloides section of the genus Potentilla, and was named Potentilla anserina. The genus Potentilla as traditionally used includes from about 300 to over 500 species. However, the group is not evolutionarily distinct (monophyletic). The Anserina group was separated into the genus Argentina by Hill in 1756 based on a single but unique morphological feature, lateral insertion of styles. The separation was supported by Rydberg in 1908 but not widely accepted. In 2010, the separation was strengthened by the discovery of a second, unique, previously unused morphological feature, ventral stipular auricles, as well as by recent molecular phylogenetic studies by Dobeš and Paule in 2010 and Töpel et al. in 2011. The new genus Argentina contains a single species, Argentina anserina, in North America and 63 species in Asia.

The separation of Argentina remains controversial. USDA PLANTS, GBIF, World Flora Online, and Plants of the World Online recognize the genus; ITIS, GRIN, NCBI, BONAP, and Flora of North America do not.

Subspecies
There are four recognized subspecies of Argentina anserina, all of them occurring in North America. Only ssp. anserina occurs in Minnesota.

Habitat

Plant

Inflorescence

Leaf