larger Canadian St. Johnswort

(Hypericum majus)

               
Conservation Status

IUCN Red List

not yet assessed

 

No image available

NatureServe

NNR - Unranked

SNR - Unranked

Minnesota

not listed

Wetland
Indicator
Status

Great Plains

FACW - Facultative wetland

Midwest

FACW - Facultative wetland

Northcentral & Northeast

FACW - Facultative wetland

Nativity

Native

Occurrence

Scattered but common

Habitat

Moist to wet. Meadows, fields, lakeshores, streamsides, edges of wetlands, roadside ditches, disturbed sites.

Flowering

June to September

     
Flower Color

Yellow

     
Height

4 to 24

     

Identification

This is an erect, perennial forb that rises from a horizontal, underground stem (rhizome) and fibrous roots. It can be 4 to 24 in height but is usually no more than 20 tall. It spreads by producing short, leafy, above-ground, horizontal stems (stolons).

The stems are erect, slender, hairless, and leafy. They have few if any branches below the inflorescence. They are ridged below the base of each leaf. They do not have black glands.

The leaves are opposite, lance-shaped to narrowly oblong or narrowly elliptic, stalkless, and more or less pointing upward. The larger leaves are ¾ to 1½ long and to wide. They are broadly angled or rounded at the tip and broadly angled, rounded, or slightly heart-shaped and weakly clasping at the base. The bases of opposite pairs of leaves meet around the stem. They have 5 to 7 veins originating at the base: a prominent midvein; one prominent vein on each side of the midvein that extends in an unbroken arc to the tip; and one or two secondary veins. The outermost veins are strongly ascending at the base. The leaf blades are dotted with sunken, brownish, translucent glands. The upper and lower surfaces are hairless. The margins are untoothed.

The inflorescence is a branched cluster of few to many flowers at the end of the stem and at the ends of a few strongly ascending branches rising from leaf nodes immediately below. The terminal clusters together with the flowering branches form a compact, flat-topped or rounded array (cyme).

The flowers are small, ¼ to in diameter. There are 5 sepals, 5 petals, 14 to 21 stamens, and 3 styles. The sepals are green, lance-shaped, and to ¼ long. They are broadest below the middle and narrowly angled with straight sides along the tip. They are erect in bud, bent backward in flower. The petals are yellow, and 1 16 to long. They shrivel and turn brown but often remain attached as the fruit develops. The stamens are not grouped. The anthers are yellow. The styles are about 1 32 long. The stigmas are often reddish.

The fruit is a maroon, elliptical to cone-shaped, 3 16 to 4 16 long, 1-chambered capsule with numerous seeds. The capsule is pointed at the top.

 
Similar
Species

Northern St. Johnswort (Hypericum boreale) sepals are broadest near the middle. The capsule is rounded at the top.

The small flower size helps to distinguish this from other Hypericum species.


Distribution Distribution Map   Sources: 2, 3, 4, 5, 7, 28.

Comments

What’s In a Name
The common name refers to the blooming period. The plant is usually in bloom on June 24, St. John’s Day.


Taxonomy

Family:

Hyperiaceae (St. Johnswort)

 

Tribe:

Hypericeae

 

Genus:

Hypericum

 

Section:

Trigynobrathys

 
Synonyms

Hypericum canadense var. majus

 
Common
Names

greater Canadian St. John’s-wort

large St. Johnswort

larger Canadian St. Johnswort


 

 

 

 

 

 

 

 

 

Glossary

Bract

Modified leaf at the base of a flower stalk or flower cluster.

 

Cyme

A branched, flat-topped or convex flower cluster in which the terminal flower opens first and the outermost flowers open last.

 

Linear

Long, straight, and narrow, with more or less parallel sides, like a blade of grass.

 

Node

The small swelling of the stem from which one or more leaves, branches, or buds originate.

 

Rhizome

A horizontal, usually underground stem. It serves as a reproductive structure, producing roots below and shoots above at the nodes.

 

Sepal

An outer floral leaf, usually green but sometimes colored, at the base of a flower.

 

Stigma

In plants, the portion of the female part of the flower that is receptive to pollen. In Odonata and Hymenoptera, a blood-filled blister or dark spot at the leading edge of each wing toward the tip, thought to dampen wing vibrations and signal mates. In Lepidoptera, an area of specialized scent scales on the forewing of some skippers, hairstreaks, and moths.

 

Stolon

An above-ground, creeping stem that grows along the ground and produces roots and sometimes new plants at its nodes. A runner.

 

Style

Part of the pistil, usually a slender stalk, connecting the ovary to the stigma(s).

       

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