Potentilla recta / sulfur cinquefoil

Adjectives: disturbed, invasive, LSRP, non-native, ruderal, undisturbed, weed, widespread

Sulfur cinquefoil is an introduced perennial that does well in a variety of habitats. It is also invasive… in undisturbed grasslands, scrublands and open forests.  Of course, disturbed sites are also good targets, e.g. roadsides, abandoned fields and heavily grazed pastures. There, it is “safe” because of the high tannin content of the leaves and stems; livestock avoid it. Although sulfur cinquefoil can spread clonally, at least a bit, it really depends on wind-dispersed seeds. The seeds do not require special treatment to germinate, and can do so in their first season, or remain in the soil up to 3 years. Longer distances are traversed by glomming onto animal fur, clothing or vehicles.

Sulfur cinquefoil flowers are pale yellow. They grow on branched inflorescences (cymes), each of which can have from one to 60 flowers. Each flower has five petals, and each of those has a notch in the center of the tip. In the center of the flower is a deeper yellow, sulfur-colored cluster of many pistils, surrounded by many rounded, flattened stamens. Flowering starts in early May and continues at least into July.

The stems are covered with shiny, erect hairs at right angles to the stem. Reaching 8 to 30 inches in height, sulfur cinquefoil has one to eight stems arising from a woody base. Below the woody base is a single taproot with several shallow, spreading lateral roots. The plant grows new shoots from this woody base in early spring and the flowering stems begin to grow in May.

Sulfur cinquefoil can be confused with native cinquefoils, but, unless it has hybridized with them, it can be distinguished by 1) long hairs perpendicular to the stem, and 2) many stem leaves but few basal leaves. The individual leaves are alternate and palmately compound, with five to nine leaflets per leaf. Leaf edges are serrated and covered with sparse, stiff hairs. Unfortunately, this last characteristic is shared by other cinquefoils. The leaves are always green (i.e. not silvery) on both surfaces but a bit lighter underneath.