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- Mentha longifolia
Mentha longifolia — horse mint
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Facts
Horse mint is native to Europe, Asia and Africa, and introduced in North America. As with other mints, it is widely used as a medicinal and culinary herb.
Habitat
Anthropogenic (man-made or disturbed habitats), shores of rivers or lakes
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
- Massachusetts
- Flower petal color
-
- blue to purple
- white
- 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 has teeth
- 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
- there are four petals, sepals, or tepals in the flower
- Fusion of sepals and petals
- the petals or the sepals are fused into a cup or tube
- Stamen number
- 4
- Fruit type (general)
- the fruit is dry but does not split open when ripe
-
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 length
- 0.28–0.38 mm
- Calyx symmetry
-
- there are two or more ways to evenly divide the calyx (the calyx is radially symmetrical)
- there is only one way to evenly divide the calyx (the calyx is bilaterally symmetrical)
- Carpels fused
- the carpels are fused to one another
- Cleistogamous flowers
- there are no cleistogamous flowers on the plan
- 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 number
- At least 4
- Flower petal color
-
- blue to purple
- white
- Flower reproductive parts
-
- the flower has both pollen- and seed-producing parts
- the flower has either only pollen- or only 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 branched above the base
- Fused stamen clusters
- NA
- Fusion of sepals and petals
- the petals or the sepals are fused into a cup or tube
- 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
- Marks on petals
- there are no noticeable marks on the petals
- Nectar spur
- the flower has no nectar spurs
- Number of carpels
- 2
- Number of sepals, petals or tepals
-
- there are five petals, sepals, or tepals in the flower
- there are four petals, sepals, or tepals in the flower
- Number of styles
- 1
- 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
-
- blue to purple
- white
- Petal appearance
- the petals are thin and delicate, and pigmented (colored other than green or brown)
- Petal folds or pleats
- the petals of the flower do not have folds or plaits
- Petal hairs (Viola)
- NA
- Petal number
- 4–5
- Petal tip shape
- the petal tip is retuse (with a blunt or rounded apex and a notch at the center)
- Petal tips (Cuscuta)
- 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 length
- 1.5–2 mm
- Sepal number
- 5
- Sepals fused only to sepals
- the sepals are fused to each other (not other flower parts), at least near their bases
- Stamen attachment
- the stamens are attached at or near the bases of the petals or tepals
- Stamen lengths differ
- the stamens are all approximately the same length
- Stamen number
- 4
- Stamen relative length
- anything
- Stamens fused
- the stamens are not attached to one another
- Staminodes
- there are no staminodes on the flower
- Style petal-like
- the styles are not petal-like
- Umbel flower reproductive parts
- NA
- Upper lip of bilabiate corolla
-
- NA
- the upper lip of the bilabiate corolla has one lobe
- the upper lip of the bilabiate corolla has two lobes
-
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
- NA
- Capsule splitting
- NA
- Fruit (pyxis) dehiscence
- NA
- Fruit beak length
- 0 mm
- Fruit features (Brassicaceae)
- NA
- Fruit locules
- four
- Fruit type (general)
- the fruit is dry but does not split open when ripe
- Fruit type (specific)
- the fruit is a schizocarp (when dry it splits into sections, each holding one or more seeds)
- Legumes (Fabaceae)
- NA
- Mericarp length
- 0.54–0.79 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
- the fruit is not flattened
- Schizocarpic fruit segments
- 4
- Seed number
- 1–4
- 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
- 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
- Underground organs
- the plant has a rhizome (a horizontal underground stem with roots growing from it)
-
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
- Floral bracts
- the flower has one or more bracts associated with it
- Hairs on leaf stalk
- the petiole has hairs on it
- Hairs on underside of leaf
- the underside of the leaf is fuzzy or hairy
- Hairs on upper side of leaf
- the upper side of the leaf is fuzzy or hairy
- Leaf arrangement
- opposite: there are two leaves per node along the stem
- Leaf blade base
- the leaf has a distinct leaf stalk (petiole)
- 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 edges
- the edge of the leaf blade has teeth
- Leaf blade hairs
- the leaf blade has simple hairs with no glands, and not tangled or wooly
- Leaf blade length
- 20–70 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)
- the leaf blade is oblong (rectangular but with rounded 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 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 spines
- there are no spines on the leaf edges
- Leaf stalk
-
- the leaves have leaf stalks
- the leaves have no leaf stalks, but attach directly to the stem
- Leaf teeth and lobes
- the leaf blade margin has forward-pointing teeth
- 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
- 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 features
- NA
- Stipules
- there are no stipules on the plant
-
Place
- Habitat
-
- terrestrial
- wetlands
- New England state
-
- Connecticut
- Massachusetts
- Specific habitat
-
- man-made or disturbed habitats
- shores of rivers or lakes
-
Scent
- Plant odor
- the plant has a pleasant smell, for example anise, fruit, mint or resin
-
Stem, shoot, branch
- Branched tendrils
- NA
- Flowering stem cross-section
- the flowering stem is roughly square
- Hair between stem nodes
- the stem has 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
- 30–150 cm
- Stem orientation
- the stems are upright or angled outwards
- Stem spacing
- the plant is solitary, or a few plants are growing together
- Tendril origin
- NA
- Tendrils
- the plant does not have tendrils
Wetland status
Not classified
In New England
Distribution
- Connecticut
- present
- Maine
- absent
- Massachusetts
- present
- New Hampshire
- absent
- Rhode Island
- absent
- Vermont
- absent
Conservation status
Exact status definitions can vary from state to state. For details, please check with your state.
- Massachusetts
- not applicable (S-rank: SNA)
From Flora Novae Angliae dichotomous key
4. Mentha longifolia (L.) L. E
horse mint. Mentha mollissima Borkh. ex P. Gaertn. et al.; M. spicata L. var. longifolia L.; M. sylvestris L. • CT, MA. Roadsides, shorelines, about dwellings.
4×M. suaveolens Ehrh. Mentha ×rotundifolia (L.) Huds. is a fertile mint hybrid known from CT, MA, ME. It is capable of forming hybrid swarms with its parental taxa. Morphologically very diverse and the extremes approach each parent. It usually has pubescent stems, tall slender spike-like inflorescences (5–10 mm thick) with largely or wholly green bracts, leaf blades 1–2 times as long as wide that are pubescent and rugose-veiny abaxially, and small pollen-bearing anthers (mostly 0.28–0.38 mm long).
4×M. suaveolens. Mentha longifolia × Mentha suaveolens → Mentha ×rotundifolia (L.) Huds. is a fertile mint hybrid known from CT, MA, ME. It is capable of forming hybrid swarms with its parental taxa. Morphologically very diverse and the extremes approach each parent. It usually has pubescent stems, tall slender spike-like inflorescences with largely or wholly green bracts, leaf blades 1–2 times as long as wide that are pubescent and rugose-veiny abaxially, and small pollen-bearing anthers (mostly 0.28–0.38 mm long). This hybrid is difficult to separaate from M. ×villosa (see that hybrid for distinguishing characteristics).
Native to North America?
No
Sometimes confused with
- Mentha spicata:
- leaf blades lanceolate to narrow-ovate, widest near the base, sometimes with a few scattered dendroid hairs on the abaxial surface, stems glabrous or rarely sparsely pubescent), and fresh plants with spearmint odor (vs. M. longifolia, with leaf blades oblong-lanceolate to oblong-elliptic or oblong-ovate, widest near the middle, pubescent entirely with simple hairs, stems pubescent, and fresh plants with musty odor).
Synonyms
- Mentha mollissima Borkh. ex P. Gaertn. et al.
- Mentha spicata L. var. longifolia L.
- Mentha sylvestris L.