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- Hypericaceae
- Hypericum
- Hypericum mutilum
Hypericum mutilum — dwarf St. John's-wort
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Facts
As in other St. John's-worts (Hypericum), the foliage of dwarf St. John's-wort contains the compound hypericin, which produces a photosensitive reaction to sunlight in light-skinned individuals.
Habitat
Meadows and fields, shores of rivers or lakes, wetland margins (edges of wetlands)
New England distribution
Adapted from BONAP data
Native: indigenous.
Non-native: introduced (intentionally or unintentionally); has become naturalized.
County documented: documented to exist in the county by evidence (herbarium specimen, photograph). Also covers those considered historical (not seen in 20 years).
State documented: documented to exist in the state, but not documented to a county within the state. Also covers those considered historical (not seen in 20 years).
Note: when native and non-native populations both exist in a county, only native status is shown on the map.
Found this plant? Take a photo and post a sighting.
Characteristics
- Habitat
-
- terrestrial
- wetlands
- New England state
-
- Connecticut
- Maine
- Massachusetts
- New Hampshire
- Rhode Island
- Vermont
- Flower petal color
-
- orange
- 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)
- Number of sepals, petals or tepals
- there are five petals, sepals, or tepals in the flower
- Fusion of sepals and petals
- both the petals and sepals are separate and not fused
- Stamen number
-
- 10
- 11
- 12
- 13 or more
- 5
- 6
- 7
- 8
- 9
- Fruit type (general)
- the fruit is dry and splits open when ripe
- Fruit length
- 2–3.5 mm
-
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 attachment
- the anther is attached near its midpoint to the filament
- Anther color
- the anthers show no hint of a pink, reddish or purplish tint
- 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
- Anther tube length
- 0 mm
- Calyx growth after flowering
- the calyx does not grow to cover or partially cover the fruit
- Calyx symmetry
- there are two or more ways to evenly divide the calyx (the calyx is radially symmetrical)
- Carpel hairs
- the carpels have no hairs
- Carpels fused
- the carpels are fused to one another
- Cilia on petals
- the petal margins do not have cilia
- 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 appearance
- the flowers appear after the leaves have appeared
- Flower description
- the flower has a superior ovary, and lacks a hypanthium
- Flower diameter
- 1–4 mm
- Flower orientation
- the flower points upwards or is angled outwards
- Flower petal color
-
- orange
- 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)
- Flowers sunken into stem
- no
- Form of style
- the style is knob-like at the tip, and unbranched
- Fringed petal edges
- the petals are not fringed
- Fused stamen clusters
- NA
- Fusion of sepals and petals
- both the petals and sepals are separate and not fused
- Hairs on flower stalk
- the flower stalk has no hairs on it
- 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
- Hypanthium length
- 0 mm
- 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
- Interior flower disk
- the flower does not have an interior disc
- Length of flower stalk
- 2–12 mm
- Marks on petals
- there are no noticeable marks on the petals
- Nectar spur
- the flower has no nectar spurs
- Number of branches in umbel
- 0
- Number of carpels
- 3
- Number of pistils
- 1
- Number of sepals, petals or tepals
- there are five petals, sepals, or tepals in the flower
- Number of styles
- 3
- Ovary position
- the ovary is above the point of petal and/or sepal attachment
- Perianth shape
- the perianth is rotate (platter-shaped, the corolla flattened, circular, with nearly horizontally spreading lobes)
- Petal and sepal arrangement
- the flower includes two cycles of petal- or sepal-like structures
- Petal and sepal colors
-
- orange
- yellow
- Petal appearance
- the petals are thin and delicate, and pigmented (colored other than green or brown)
- Petal base
- the petal narrows gradually or does not narrow at the base
- 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 glandular dots or scales
- no
- Petal hairs (Viola)
- NA
- Petal hairs on inner/upper surface
- there are no hairs on the inner/upper petal surface
- Petal length
- 1.5–2.5 mm
- Petal length relative to sepals
- the petals are about equal in length to the sepals
- Petal nectaries
- the petals do not have nectaries
- Petal number
- 5
- Petal shape
- the petal outline is oblong (rectangular, but with rounded ends)
- Petal tip shape
- the petal tip is obtuse (bluntly pointed)
- Petal tips (Cuscuta)
- NA
- Raceme attachment (Veronica)
- NA
- Reproductive system
- all the flowers have both carpels and stamens (synoecious)
- 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 auricles
- the sepals have no auricles
- Sepal cilia
- the sepals do not have cilia
- Sepal color
- green to brown
- Sepal features
- one or more sepals have glands on the surface of the sepal
- Sepal length
- 2.5–3.5 mm
- Sepal number
- 5
- Sepal orientation
- the sepals are pressed against the corolla, or jutting stiffly upward
- Sepal relative length
- NA
- Sepal shape
-
- the sepal outline is lanceolate (lance-shaped; narrow, gradually tapering from the base to the tip)
- the sepal outline is linear (extremely narrow, thread-like)
- the sepal outline is oblong (rectangular, but with rounded ends)
- Sepal texture
- the sepals are either very thin but flexible, like a membrane, or they are leaf-like in texture
- Sepal tip shape
-
- the sepal tip is acute (is sharply pointed)
- the sepal tip is obtuse (is bluntly pointed)
- Sepal uniformity
- all the sepals are about the same size
- Sepals fused only to sepals
- the sepals are separate from one another
- Spur length
- 0 mm
- Spur number
- NA
- Stamen appendages
- stamen appendages are absent
- Stamen attachment
- the stamens are not attached to the petals or tepals
- Stamen number
-
- 10
- 11
- 12
- 13 or more
- 5
- 6
- 7
- 8
- 9
- Stamen position relative to petals
- NA
- Stamen relative length
- anything
- Stamens fused
- the stamens are not attached to one another
- Staminodes
- there are no staminodes on the flower
- Stigma position
- the stigmas are positioned at the tip of the style
- Style length
- Up to 1 mm
- Style petal-like
- the styles are not petal-like
- Style relative length
- NA
- Surface of ovary
- the ovary surface has no points, bumps or wrinkles
- 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 ribs
- the capsule has no prominent ribs or wings
- Capsule splitting
- the capsule splits by three main valves, teeth or pores
- Carpel beak length
- 0 mm
- Fruit (pyxis) dehiscence
- NA
- Fruit beak length
- 0 mm
- Fruit cross-section
- the fruit is round in cross-section
- Fruit features (Brassicaceae)
- NA
- Fruit length
- 2–3.5 mm
- Fruit length relative to sepals
- the fruit is about the same length as its associated sepals
- Fruit locules
- one
- Fruit shape
-
- the fruit is ellipsoid (widest in the middle and tapering to each end)
- the fruit is ovoid (egg-shaped)
- Fruit stalk orientation
- the fruits point upward or spread or curve outward
- 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)
- Hair type on fruit
- NA
- 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
- Ovary stipe length
- 0 mm
- Placenta arrangement
- the plant has parietal placentation, where ovules develop on the wall or slight outgrowths of the wall forming broken partitions within a compound ovary
- Rows of seeds in fruit (Brassicaceae)
- NA
- Schizocarpic fruit compression
- NA
- Schizocarpic fruit segments
- 0
- Seed length
- 0.4–0.7 mm
- Seed relative length
- the seed is longer than it is wide
- Seed surface
-
- the seed is covered with reticulate markings (a netlike pattern due to splitting and rejoining of lines or ridges)
- the seed is hairless
- the seed is smooth or without clear markings
- Seeds comose
- no hairs
- 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 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
- the plant lives only a single year or less
- Parasitism
- the plant is not parasitic
- Plant color
- the leaves or young stems of the plant are green
- Plants darken when dry
- no
- Spines on plant
- the plant has no spines
- Underground organs
- the plant has a rhizome (a horizontal underground stem with roots growing from it)
-
Leaves
- Bracteole edges
- NA
- Bracteole length
- 0 mm
- Bracteole number (Apiaceae)
- 0
- Bracteole shape
- NA
- Bracteoles
- there are no bracteoles on the plant
- 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
- Floral bract texture
- the floral bracts are green, with a leaf-like texture
- Floral bracts
- the flower has one or more bracts associated with it
- Flower bract length
- 1–4 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
- no
- Inflated hairs on leaf
- the leaf blade does not have inflated hairs on it
- 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
-
- the base of the leaf blade is cuneate (wedge-shaped, tapers to the base with relatively straight, converging edges), or narrow
- the base of the leaf blade is rounded
- Leaf blade base symmetry
- the leaf blade base is symmetrical
- Leaf blade bloom
-
- the underside of the leaf has no noticeable bloom
- there is a noticeable powdery or waxy bloom on the underside of the leaf
- Leaf blade edges
- the edge of the leaf blade is entire (has no teeth or lobes)
- Leaf blade flatness
- the leaf is flat (planar) at the edges
- Leaf blade hairs
- NA
- Leaf blade length
- 10–40 mm
- Leaf blade primary vein pattern
- the secondary veins branch off at intervals from the primary vein
- 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)
- the leaf blade is ovate (widest below the middle and broadly tapering at both ends)
- Leaf blade surface colors
- the upper side of the leaf blade is relatively uniform in color
- Leaf blade texture
- the leaf blade is herbaceous (has a leafy texture)
- Leaf blade vein pattern
- the major veins of the leaf blade branch, but do not rejoin
- Leaf blade veins
- the leaf blade has one main vein running from the base towards the tip (it may or may not have secondary veins)
- Leaf blade width
- Up to 15 mm
- Leaf duration
-
- the leaves drop off in winter (or they whither but persist on the plant)
- the leaves remain green all winter
- Leaf form
- the leaves are green, with an expanded blade and a leaf-like texture
- Leaf hair orientation
- NA
- Leaf sheath length
- 0 mm
- Leaf shiny
- the upper side of the leaf is dull or slightly shiny
- 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 stalk attachment to leaf
- NA
- Leaf stalk base
- NA
- Leaf stalk length
- 0 mm
- 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 tufts in axils
- there are no clusters of smaller leaves growing out of axils
- Leaf type
- the leaves are simple (i.e., lobed or unlobed but not separated into leaflets)
- Leaf types
- NA
- 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)
- Stipels
- NA
- Stipule edges
- NA
- Stipule features
- NA
- Stipule fused to leaf stalk
- NA
- Stipule length
- 0 mm
- Stipule shape
- NA
- Stipules
- there are no stipules on the plant
- Teeth per side of leaf blade
- 0
-
Place
- Habitat
-
- terrestrial
- wetlands
- New England state
-
- Connecticut
- Maine
- Massachusetts
- New Hampshire
- Rhode Island
- Vermont
- Specific habitat
-
- edges of wetlands
- meadows or fields
- shores of rivers or lakes
-
Scent
- Plant odor
- the plant does not have much of a smell
-
Stem, shoot, branch
- Branched tendrils
- NA
- Direction of stem hairs
- NA
- Flowering stem cross-section
-
- the flowering stem is circular, or with lots of small angles so that it is roughly circular
- the flowering stem is roughly square
- Hair between stem nodes
- the stem has no hairs between the nodes
- Hairs between stem nodes
- NA
- Hooked hairs on stem between nodes
- no
- Leaves on stem
- there is at least one full leaf above the base of the flowering stem
- Length of hairs between stem nodes
- 0 mm
- Plant height
- 10–80 cm
- Stem bloom
-
- the stem has a powdery or waxy film on it that can be rubbed away
- there is no powdery or waxy film on the stem
- Stem hair distribution
- NA
- Stem nodes swollen
- the stem is not swollen at the nodes
- Stem orientation
- the stems are upright or angled outwards
- Stem roughness between nodes
- the stem does not feel rough
- Stem spacing
-
- the plant is growing in tufts, or compact clusters with closely spaced stems, or it is densely matted together in clumps, cushionlike
- the plant is solitary, or a few plants are growing together
- Stem succulence
- the stems are not succulent
- Tendril origin
- NA
- Tendrils
- the plant does not have tendrils
- Wings on stem
-
- the stem does not have wings on it
- the stem has wings on it that run down the stem from the leaf nodes
Wetland status
Usually occurs in wetlands, but occasionally in non-wetlands. (Wetland indicator code: FACW)
In New England
Distribution
- Connecticut
- present
- Maine
- present
- Massachusetts
- present
- New Hampshire
- present
- Rhode Island
- present
- Vermont
- present
Conservation status
Exact status definitions can vary from state to state. For details, please check with your state.
- Massachusetts
- widespread (S-rank: S5)
From Flora Novae Angliae dichotomous key
11. Hypericum mutilum L. N
dwarf St. John’s-wort. Hypericum mutilum L. var. parviflorum (Willd.) Fern. • CT, MA, ME, NH, RI, VT. Shorelines, low fields, wetland edges.
4×11. Hypericum canadense × Hypericum mutilum → This rare St. John’s-wort hybrid is known from ME. It is similar to H. ×dissimulatum (3 ×4) except that the sepals tend to be more pointed at apex (sharply acute vs. merely acute; side by side comparison of specimens is useful here).
10×11. Hypericum majus × Hypericum mutilum → This very rare St. John’s-wort hybrid is known from ME. It can be recognized by its intermediate capsule shape, similar to H. ×dissimulatum (3 ×4). It differs fromH. ×dissimulatum in that the leaf blades average broader (principal ones 4.8–10.8 mm wide vs. 1.5–10 mm).
Native to North America?
Yes and no (some introduced)
Sometimes confused with
- Hypericum boreale:
- bracts of inflorescence leaf-like and sepals shorter than the capsule (vs. H. mutilum, with bracts of inflorescence tiny, not resembling the leaves and sepals approximately as long as the capsule).
- Hypericum canadense:
- capsule pointed at apex and sepals broadest below the middle (vs. H. mutilum, with the capsule rounded at apex and sepals broadest near middle).
- Hypericum majus:
- capsule pointed at apex and sepals broadest below the middle (vs. H. mutilum, with the capsule rounded at apex and sepals broadest near middle).
Synonyms
- Hypericum mutilum var. parviflorum (Willd.) Fern.