Your help is appreciated. We depend on donations to help keep this site free and up to date for you. Can you please help us?

Donate

Native Plant Trust: Go Botany Discover thousands of New England plants

Hypericum ascyron — great St. John's-wort

Copyright: various copyright holders. To reuse an image, please click it to see who you will need to contact.

Facts

Great St. John's-wort is native to northeastern and midwestern North America, as well as eastern Asia. In New England it is rare in some states, and is primarily found in the west. It grows in riparian forests, river banks and low fields.

Habitat

Floodplain (river or stream floodplains), marshes, meadows and fields, shores of rivers or lakes

New England distribution

Adapted from BONAP data

Found this plant? Take a photo and post a sighting.

North America distribution

Adapted from BONAP data

enlarge

Characteristics

Habitat
terrestrial
Flower petal color
yellow
Leaf type
the leaves are simple (i.e., lobed or unlobed but not separated into leaflets)
Leaf arrangement
opposite: there are two leaves per node along the stem
Leaf blade edges
the edge of the leaf blade is entire (has no teeth or lobes)
Flower symmetry
  • there are two or more ways to evenly divide the flower (the flower is radially symmetrical)
  • there is no way to evenly divide the flower (the flower is asymmetrical)
Number of sepals, petals or tepals
there are five petals, sepals, or tepals in the flower
Stamen number
13 or more
Fruit type (general)
the fruit is dry and splits open when ripe
Fruit length
15–30 mm
Show all characteristics

  • Clonal plantlets

    Bulbils
    the plant does not appear to have bulbils
    Bulblets replace flowers
    there are no bulblets where the flowers are located

  • Flowers

    Anther opening
    the anthers have narrow slits or furrows that run lengthwise along the anthers
    Anther spurs
    the anthers do not have spurs on them
    Calyx symmetry
    there are two or more ways to evenly divide the calyx (the calyx is radially symmetrical)
    Carpels fused
    the carpels are fused to one another
    Cleistogamous flowers
    there are no cleistogamous flowers on the plan
    Corolla morphology
    NA
    Corolla palate
    no
    Corona lobe length
    0 mm
    Epicalyx
    the flower does not have an epicalyx
    Epicalyx number of parts
    0
    Filament surface
    the filament is smooth, with no hairs or scales
    Flower description
    the flower has a superior ovary, and lacks a hypanthium
    Flower diameter
    40–60 mm
    Flower number
    At least 1
    Flower petal color
    yellow
    Flower reproductive parts
    the flower has both pollen- and seed-producing parts
    Flower symmetry
    • there are two or more ways to evenly divide the flower (the flower is radially symmetrical)
    • there is no way to evenly divide the flower (the flower is asymmetrical)
    Flowers sunken into stem
    no
    Form of style
    NA
    Fused stamen clusters
    there are five clusters of fused stamens
    Hairs on inflorescence
    the axis of the inflorescence has no hairs on it
    Horns in hoods (Asclepias)
    NA
    Hypanthium
    the flower does not have a hypanthium
    Inflorescence one-sided
    the flowers are arrayed in a spiral around the inflorescence axis or branches, or occur singly, or in several ranks
    Inner tepals (Rumex)
    NA
    Nectar spur
    the flower has no nectar spurs
    Number of carpels
    Up to 5
    Number of pistils
    5
    Number of sepals, petals or tepals
    there are five petals, sepals, or tepals in the flower
    Number of styles
    5
    Ovary position
    the ovary is above the point of petal and/or sepal attachment
    Petal and sepal arrangement
    the flower includes two cycles of petal- or sepal-like structures
    Petal and sepal colors
    yellow
    Petal appearance
    the petals are thin and delicate, and pigmented (colored other than green or brown)
    Petal folding in bud
    the petals in bud are rolled like an umbrella, each petal having one edge tucked inside and the other edge exposed (convolute)
    Petal folds or pleats
    the petals of the flower do not have folds or plaits
    Petal hairs (Viola)
    NA
    Petal length
    25–30 mm
    Petal length relative to sepals
    the petals are longer than the sepals
    Petal number
    5
    Petal tips (Cuscuta)
    NA
    Raceme attachment (Veronica)
    NA
    Scales inside corolla
    no
    Sepal and petal color
    the sepals are different from the petals
    Sepal appearance
    the sepals are green or brown, and leaf-like in texture
    Sepal appendages
    the sepals do not have appendages on them
    Sepal appendages (Oenothera)
    NA
    Sepal number
    5
    Sepal relative length
    NA
    Sepal uniformity
    all the sepals are about the same size
    Sepals fused only to sepals
    the sepals are separate from one another
    Stamen number
    13 or more
    Stamens fused
    the stamens are attached to one another at or near their bases
    Staminodes
    there are no staminodes on the flower
    Stigma position
    the stigmas are positioned at the tip of the style
    Style petal-like
    the styles are not petal-like
    Umbel flower reproductive parts
    NA
    Upper lip of bilabiate corolla
    NA

  • Fruits or seeds

    Achene relative orientation
    NA
    Achene shape
    NA
    Achene surface (Polygonum)
    NA
    Achene type
    NA
    Berry color
    NA
    Capsule color (Viola)
    NA
    Capsule splitting
    the capsule splits by five main valves, teeth or pores
    Fruit (pyxis) dehiscence
    NA
    Fruit features (Brassicaceae)
    NA
    Fruit length
    15–30 mm
    Fruit locules
    five
    Fruit shape
    conical
    Fruit type (general)
    the fruit is dry and splits open when ripe
    Fruit type (specific)
    the fruit is a capsule (splits along two or more seams, apical teeth or pores when dry, to release two or more seeds)
    Hairs on fruit
    the fruits are not hairy
    Legumes (Fabaceae)
    NA
    Mericarp length
    0 mm
    Mericarp segment shape (Desmodium)
    NA
    Other markings on berry
    NA
    Ovary stipe
    the ovary or fruit does not have a stipe
    Placenta arrangement
    the plant has axile placentation, in which the ovules are attached where the septa of a compound ovary are united, usually on the central axis, or to the septa themselves
    Rows of seeds in fruit (Brassicaceae)
    NA
    Schizocarpic fruit compression
    NA
    Schizocarpic fruit segments
    0
    Seed surface
    the seed is smooth or without clear markings
    Septum in fruit (Brassicaceae)
    NA
    Wings on fruit
    the fruit does not have wings on it
    prickles on fruits
    the fruits do not have thorn-like defensive structures

  • Glands or sap

    Glands on leaf blade
    • the leaf blades do not have glandular dots or scales
    • the leaf blades have glandular dots or scales
    Sap
    the sap is clear and watery
    Sap color
    the sap is clear

  • Growth form

    Growth form
    the plant is an herb (it has self-supporting stems)
    Lifespan
    the plant lives more than two years
    Parasitism
    the plant is not parasitic
    Plant color
    the leaves or young stems of the plant are green
    Spines on plant
    the plant has no spines

  • Leaves

    Bracteole number (Apiaceae)
    0
    Bracts in plantain (Plantago)
    NA
    Final leaf segment length (compound lvs only)
    0 mm
    Final leaf segment length to width ratio (compound lvs only)
    0
    Final leaf segment width (compound lvs only)
    0 mm
    Hairs on leaf stalk
    NA
    Hairs on underside of leaf
    the underside of the leaf is not hairy, or it has very few hairs
    Hairs on upper side of leaf
    the upper side of the leaf is not hairy, or it has very few hairs
    Hooked hairs on underside of leaf
    NA
    Inflated hairs on leaf
    NA
    Leaf arrangement
    opposite: there are two leaves per node along the stem
    Leaf blade base
    • the leaf has no stalk
    • the leaf has no stalk and at the base it clasps the stem
    Leaf blade base shape
    NA
    Leaf blade edges
    the edge of the leaf blade is entire (has no teeth or lobes)
    Leaf blade hairs
    NA
    Leaf blade length
    40–100 mm
    Leaf blade shape
    • the leaf blade is elliptic (widest near the middle and tapering at both ends)
    • the leaf blade is lanceolate (lance-shaped; widest below the middle and tapering at both ends)
    Leaf blade surface colors
    the upper side of the leaf blade is relatively uniform in color
    Leaf duration
    the leaves drop off in winter (or they whither but persist on the plant)
    Leaf form
    the leaves are green, with an expanded blade and a leaf-like texture
    Leaf hair orientation
    NA
    Leaf spines
    there are no spines on the leaf edges
    Leaf stalk
    the leaves have no leaf stalks, but attach directly to the stem
    Leaf teeth and lobes
    the edge of the leaf blade is entire (has no teeth or lobes)
    Leaf tip
    • the tip of the leaf blade is acute (sharply pointed)
    • the tip of the leaf blade is obtuse (bluntly pointed)
    Leaf type
    the leaves are simple (i.e., lobed or unlobed but not separated into leaflets)
    Leaf variation
    the leaves are nearly similar in size, prominence of teeth, and length of stalks throughout the stem
    Leaflet number
    0
    Leaflet petiolules
    NA
    Leaves per node
    there are two leaves per node along the stem
    Pinnately compound leaf type
    NA
    Specific leaf type
    the leaves are simple (i.e., lobed or unlobed but not separated into leaflets)
    Stipule edges
    NA
    Stipule features
    NA
    Stipule fused to leaf stalk
    NA
    Stipule shape
    NA
    Stipules
    there are no stipules on the plant
    Teeth per side of leaf blade
    0

  • Place

    Habitat
    terrestrial
    Specific habitat
    • marshes
    • meadows or fields
    • river or stream floodplains
    • shores of rivers or lakes

  • Scent

    Plant odor
    the plant does not have much of a smell

  • Stem, shoot, branch

    Branched tendrils
    NA
    Hair between stem nodes
    the stem has no hairs between the nodes
    Hooked hairs on stem between nodes
    no
    Leaves on stem
    there is at least one full leaf above the base of the flowering stem
    Plant height
    70–150 cm
    Stem orientation
    the stems are upright or angled outwards
    Tendril origin
    NA
    Tendrils
    the plant does not have tendrils

Wetland status

Occurs in wetlands or non-wetlands. (Wetland indicator code: FAC)

In New England

Distribution

Connecticut
present
Maine
present
Massachusetts
present
New Hampshire
present
Rhode Island
absent
Vermont
present

Conservation status

Exact status definitions can vary from state to state. For details, please check with your state.

Connecticut
rare (S-rank: S2), special concern (code: SC)
Maine
extremely rare (S-rank: S1), endangered (code: E)
Massachusetts
extremely rare (S-rank: S1), endangered (code: E)
Vermont
rare (S-rank: S2), threatened (code: T)

ssp. pyramidatum

New Hampshire
extremely rare (S-rank: S1), endangered (code: E)

From Flora Novae Angliae dichotomous key

2.  Hypericum ascyron L. N

great St. John’s-wort. Hypericum pyramidatum Ait. • CT, MA, ME, NH, VT; found primarily in western New England. Riparian forests, river banks, low fields.

Native to North America?

Yes

Synonyms

  • Hypericum pyramidatum Ait.

Family

Hypericaceae

Genus

Hypericum