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Weed Identification

spotted St. Johnswort

Family

Hypericaceae

Scientific Name

Hypericum punctatum

Other Common Names:

dotted St. Johnswort

Synonyms (former Scientific Names):

Hypericum subpetiolatum

Habit

Herb

Leaves

The oval leaves of Spotted St. Johnswort are hairless, easily seen veins, and arranged opposite each other without a petiole. They are larger than those of Common St. Johnswort at 2.5 inches (63mm) long and 1 inches (25mm) wide and have a more blunt tip. Margins are smooth and the leaves typically do not have a petiole, if they do it is very short. Smaller leaves can be seen on the axils of other leaves. Semi-Translucent, but mostly black dots are seen from the undersides of the leaves. It may also cause phytotoxicity to light colored animals through toxins (hypericin).

Identifying Characteristics

Spotted St. Johnswort typically grows to 2.5-3 ft tall and may sometimes branch. Most of its stems end in a cluster of yellow flowers. It is similar to Common St. Johnswort; however, there are a few distinct differences. The dots are more prevalent on the leaves and flower petals. Its stem is more red and green than These dots are also less translucent, but black rather than the Hypericum perforatum. It also has larger leaves but smaller flowers than the Common St. Johnswort. Like Common St. Johnswort, Spotted can spread vegetatively (by short rhizomes off its taproot) or by seed.

Flower Seed Head

The flowers are typically yellow and around 1/2 inch (12mm) across with 5 petals. One of the most distinguishing characteristics is its spots on the petals. They are of a darker color and may be seen in streaks. Styles are yellow and often have red tips.

Seed Fruit

Fruit is red/purple and about a 1/4 inch (6mm) long. The seed is small and pods split into 3 parts. Seed can be carried by the wind to be spread.

Where Found

Forests, Pastures, roadsides, etc.

Growth Habit

upright and nonwoody

Thorns or Spines

not present

Approximate Flower Diameter

Varies: 
pencil
dime

Dominant Flower Color

yellow

Flower Symmetry

radial symmetery

Leaf Hairs

no hairs

Leaf Shape

Varies: 
lance
oval

Leaf Arrangement

opposite

Leaf Margin

entire

Leaf Structure

simple

Leaf Stalk

Varies: 
none
shorter than leaf

Stem Hairs

no hairs

Stem Cross Section

round or oval

Milky Sap

not present

Root Structure

Varies: 
taproot
rhizomes present

Life Cycle

perennial

Ochrea

not present

Plant Type

Herb