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

Triosteum aurantiacum — orange-fruited horse-gentian

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New England distribution

Adapted from BONAP data

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North America distribution

Adapted from BONAP data

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Facts

In spite of the popular name, orange-fruited horse-gentian is not a gentian (Gentianaceae); rather, it is related to the honeysuckles. The Iroquois used an infusion of this plant for soaking sore feet.

Habitat

Forest edges, forests, woodlands

Characteristics

Habitat
terrestrial
New England state
  • Connecticut
  • Maine
  • Massachusetts
  • New Hampshire
  • Rhode Island
  • Vermont
Flower petal color
  • blue to purple
  • pink to red
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 is only one way to evenly divide the flower (the flower is bilaterally symmetrical)
Number of sepals, petals or tepals
there are five 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
5
Fruit type (general)
the fruit is fleshy
Fruit length
8–10 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 palate
    no
    Corona lobe length
    0 mm
    Epicalyx
    the flower does not have an epicalyx
    Epicalyx number of parts
    0
    Flower description
    the flower has an inferior ovary, with or without a hypanthium
    Flower length
    8–17 mm
    Flower number
    1–5
    Flower petal color
    • blue to purple
    • pink to red
    Flower reproductive parts
    the flower has both pollen- and seed-producing parts
    Flower symmetry
    there is only one way to evenly divide the flower (the flower is bilaterally symmetrical)
    Flowers sunken into stem
    no
    Form of style
    the style is knob-like at the tip, and unbranched
    Fusion of sepals and petals
    the petals or the sepals are fused into a cup or tube
    Hairs on flower stalk
    NA
    Hairs on inflorescence
    at least some of the hairs on the axis of the inflorescence have glands
    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
    Length of flower stalk
    0 mm
    Length of peduncle
    0 mm
    Marks on petals
    • the petals have spots or streaks on them
    • there are no noticeable marks on the petals
    Nectar spur
    the flower has no nectar spurs
    Number of branches in umbel
    0
    Number of sepals, petals or tepals
    there are five petals, sepals, or tepals in the flower
    Number of styles
    1
    Ovary position
    the ovary is below the point of petal and/or sepal attachment
    Perianth shape
    • the perianth is campanulate (bell-shaped, with a tube about as long as wide, flaring at the mouth)
    • the perianth is cylindric (tube-shaped)
    Petal and sepal arrangement
    the flower includes two cycles of petal- or sepal-like structures
    Petal and sepal colors
    • blue to purple
    • pink to red
    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 length
    10–15 mm
    Petal nectaries
    the petals have at least one nectary
    Petal number
    5
    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 color
    • blue to purple
    • green to brown
    • pink to red
    Sepal length
    10–18 mm
    Sepal number
    5
    Sepal shape
    the sepal outline is linear (extremely narrow, thread-like)
    Sepal uniformity
    all the sepals are about the same size
    Stamen attachment
    the stamens are attached at or near the bases of the petals or tepals
    Stamen number
    5
    Stamen position relative to petals
    the stamens are lined up with the sepals
    Stamen relative length
    anything
    Staminodes
    there are no staminodes on the flower
    Style petal-like
    the styles are not petal-like
    Style relative length
    the stigma does not protrude beyond the mouth of the corolla
    Umbel flower reproductive parts
    NA
    Upper lip of bilabiate corolla
    • NA
    • 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
    • orange
    • red
    Capsule color (Viola)
    NA
    Capsule ribs
    NA
    Capsule splitting
    NA
    Carpel beak length
    0 mm
    Fruit (pyxis) dehiscence
    NA
    Fruit beak length
    0 mm
    Fruit cross-section
    • the fruit is roughly triangular in cross-section
    • the fruit is round in cross-section
    Fruit features (Brassicaceae)
    NA
    Fruit length
    8–10 mm
    Fruit locules
    four
    Fruit shape
    • the fruit is pyriform (roughly pear-shaped)
    • the fruit is spherical
    Fruit stalk orientation
    NA
    Fruit type (general)
    the fruit is fleshy
    Fruit type (specific)
    the fruit is a drupe (fleshy, with a firm inner ovary wall that encloses a single seed)
    Hair type on fruit
    the hairs on the fruits have glands at their tips
    Hairs on fruit
    the fruits have hairs on them
    Legumes (Fabaceae)
    NA
    Mericarp length
    0 mm
    Mericarp segment shape (Desmodium)
    NA
    Other markings on berry
    the ripe berries are mostly one color without spots or streaks
    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 number
    3
    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
    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)
    Horizontal rooting stem
    the plant does not have stolons
    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
    Bracteole shape
    the bracteoles are lanceolate (widest below the middle, and tapering at both ends)
    Bracteoles
    the plant has bracteoles between the primary bracts and the flowers
    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
    NA
    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
    • 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
    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
    Leaf blade base symmetry
    the leaf blade base is symmetrical
    Leaf blade bloom
    the underside of the leaf has no noticeable bloom
    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
    the leaf blade has simple hairs with no glands, and not tangled or wooly
    Leaf blade length
    100–300 mm
    Leaf blade primary vein pattern
    the secondary veins branch off at intervals from the primary vein
    Leaf blade shape
    • the leaf blade is oblong (rectangular but with rounded ends)
    • the leaf blade is obovate (egg-shaped, but with the widest point above the middle of the leaf blade)
    • 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
    40–150 mm
    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 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 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
    New England state
    • Connecticut
    • Maine
    • Massachusetts
    • New Hampshire
    • Rhode Island
    • Vermont
    Specific habitat
    • edges of forests
    • forests
    • woodlands

  • Scent

    Plant odor
    the plant does not have much of a smell

  • Stem, shoot, branch

    Branched tendrils
    NA
    Direction of stem hairs
    the hairs point mostly upwards to outwards
    Hair between stem nodes
    the stem has hairs between the nodes
    Hairs between stem nodes
    at least some of the hairs on the stem have glands
    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
    0.5–1.5 mm
    Plant height
    Up to 130 cm
    Stem bloom
    there is no powdery or waxy film on the stem
    Stem hair distribution
    the hairs on the stem are distributed more of less uniformly
    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
    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

Wetland status

Not classified

New England distribution and conservation status

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.

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

var. aurantiacum

Massachusetts
fairly widespread (S-rank: S4)
Rhode Island
extremely rare (S-rank: S1), concern (code: C)
Vermont
uncommon (S-rank: S3)

Native to North America?

Yes

Sometimes confused with

Triosteum angustifolium:
sepals 9–12 mm long, conspicuously hispid-ciliate, the abaxial surface glabrous or short-pubescent, stem long-pubescent, the longer hairs 1.5–3 mm long, and leaf blades 2–6 cm wide (vs. T. aurantiacum, with sepals 10–18 mm long, the margins and abaxial surface pubescent with hairs of uniform length, stem pubescent with hairs up to 2 mm long, and leaf blades 4–15 cm wide).
Triosteum perfoliatum:
leaf blades of the middle nodes broadly connate at base, the lower ones and the upper ones sometimes sessile or petiolate, stem short-pubescent, the eglandular hairs up to 0.5 mm long with a few scattered hairs may range to 1.5 mm, and sepals 0.9–2 mm wide (vs. T. aurantiacum, with leaf blades not basally connate or sometimes the middle nodes with slightly gamophyllous leaves, stem with longer pubescence, the eglandular hairs 0.5–1.5 mm long, and sepals 1.5–2.8 mm wide).

Synonyms

  • Triosteum perfoliatum L. var. aurantiacum (Bickn.) Wieg.

Family

Caprifoliaceae

Genus

Triosteum

Notes on subspecies and varieties in New England

Our variety is Triosteum aurantiacum Bickn. var. aurantiacum.

Help

From the dichotomous key of Flora Novae Angliae

2.  Triosteum aurantiacum Bickn. var. aurantiacum N

orange-fruited horse-gentian. Triosteum perfoliatum L. var.  aurantiacum (Bickn.) Wieg. 
• CT, MA, ME, NH, RI, VT. Dry-mesic to mesic forests, woodlands, and forest borders.

1×2. Triosteum angustifolium × Triosteum aurantiacum → Triosteum ×‌eamesii (Wieg.) A. Haines is a rare horse-gentian hybrid that is known from CT and was formerly treated as Triosteum angustifolium var. eamesii Wieg. It most resembles T. angustifolium due to its short sepals and long-pubescent stems. It has leaf blades mostly 2.2–3.2 times a long as wide that are moderately puberulent abaxially and dried stems (3–) 4–7 mm thick at the midpoint (vs. leaf blades mostly 3.5–7 times as long as wide that are sparsely pubescent abaxially and dried stems 2–2.7 mm thick at the midpoint in T. angustifolium). Recognition of this hybrid shows T. angustifolium to be far more rare than previously believed because many collections of T. angustifolium were of the var. eamesii (i.e., they were hybrid plants).