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

Proboscidea louisianica — ram's-horn

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Facts

Ram's-horn (aka Louisiana unicorn-plant) is native to the south-central U. S. and introduced in New England, where it can be found in fields and cultivated areas. This is one of only a few species in the Pediliaceae in our region. It gets its common name from the curving horn-shaped pod; the pod contains pigments that have been used in traditional black dyes for basketry by the Shoshoni and other Native American tribes.

Habitat

Anthropogenic (human-disturbed or -maintained habitats), meadows and fields

New England distribution

Adapted from BONAP data

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North America distribution

Adapted from BONAP data

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Characteristics

Habitat
terrestrial
New England state
  • Connecticut
  • Massachusetts
  • Rhode Island
  • Vermont
Flower petal color
  • white
  • yellow
Leaf type
the leaves are simple (i.e., lobed or unlobed but not separated into leaflets)
Leaf arrangement
  • alternate: there is one leaf per node along the stem
  • 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
4
Fruit length
100–200 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 spurs
    the anthers do not have spurs on them
    Calyx symmetry
    there is only one way to evenly divide the calyx (the calyx is bilaterally symmetrical)
    Cleistogamous flowers
    there are no cleistogamous flowers on the plan
    Corolla palate
    no
    Corona lobe length
    0 mm
    Epicalyx number of parts
    0
    Flower description
    the flower has a superior ovary, and lacks a hypanthium
    Flower number
    8–20
    Flower petal color
    • white
    • yellow
    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 lobed at the tip, and unbranched
    Fusion of sepals and petals
    the petals or the sepals are fused into a cup or tube
    Horns in hoods (Asclepias)
    NA
    Inner tepals (Rumex)
    NA
    Marks on petals
    the petals have spots or streaks on them
    Nectar spur
    the flower has no nectar spurs
    Number of carpels
    2
    Number of pistils
    1
    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 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
    • white
    • yellow
    Petal appearance
    the petals are thin and delicate, and pigmented (colored other than green or brown)
    Petal hairs (Viola)
    NA
    Petal length
    35–55 mm
    Petal number
    5
    Petal tips (Cuscuta)
    NA
    Scales inside corolla
    no
    Sepal and petal color
    the sepals are different from the petals
    Sepal appendages
    the sepals do not have appendages on them
    Sepal appendages (Oenothera)
    NA
    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 number
    4
    Stamen position relative to petals
    the stamens are lined up with the sepals
    Staminodes
    the flower has staminodes
    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

  • Fruits or seeds

    Achene shape
    NA
    Achene surface (Polygonum)
    NA
    Capsule color (Viola)
    NA
    Fruit (pyxis) dehiscence
    NA
    Fruit features (Brassicaceae)
    NA
    Fruit length
    100–200 mm
    Fruit locules
    one
    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)
    Legumes (Fabaceae)
    NA
    Mericarp segment shape (Desmodium)
    NA
    Other markings on berry
    NA
    Rows of seeds in fruit (Brassicaceae)
    NA
    Schizocarpic fruit compression
    NA
    Schizocarpic fruit segments
    0
    Septum in fruit (Brassicaceae)
    NA
    prickles on fruits
    • the fruits are armed with thorns-like defensive structures
    • 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)
    Lifespan
    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
    • there are spines on the plant

  • Leaves

    Bracteole number (Apiaceae)
    0
    Bracts in plantain (Plantago)
    NA
    Final leaf segment length (compound lvs only)
    0 mm
    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
    • alternate: there is one leaf per node along the stem
    • 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 cordate (heart-shaped, has rounded lobes at the base)
    Leaf blade edges
    the edge of the leaf blade is entire (has no teeth or lobes)
    Leaf blade length
    Up to 250 mm
    Leaf blade shape
    • the leaf blade is cordate (heart-shaped with backward-facing rounded lobes), or sagittate (arrow-shaped with backward-facing pointed lobes)
    • the leaf blade is orbicular (roughly circular, as wide as long)
    • the leaf blade is reniform (kidney-shaped; wider than long)
    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
    Leaf teeth and lobes
    • the edge of the leaf blade is entire (has no teeth or lobes)
    • the leaf blade margin is wavy, but does not have teeth
    Leaf type
    the leaves are simple (i.e., lobed or unlobed but not separated into leaflets)
    Leaves per node
    • there are two leaves per node along the stem
    • there is one leaf per node along the stem
    Specific leaf type
    the leaves are simple (i.e., lobed or unlobed but not separated into leaflets)
    Stipule features
    NA
    Stipules
    there are no stipules on the plant

  • Place

    Habitat
    terrestrial
    New England state
    • Connecticut
    • Massachusetts
    • Rhode Island
    • Vermont
    Specific habitat
    • human-disturbed or -maintained habitats
    • meadows or fields

  • Stem, shoot, branch

    Branched tendrils
    NA
    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
    Plant height
    At least 60 cm
    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
present
Vermont
present

Conservation status

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

Massachusetts
not applicable (S-rank: SNA)

ssp. louisianica

Massachusetts
unranked (S-rank: SNR)

Subspecies and varieties

Our subspecies is Proboscidea louisianica (P. Mill.) Thellung ssp. louisianica.

From Flora Novae Angliae dichotomous key

1.  Proboscidea louisianica (P. Mill.) Thellung ssp. louisianica E

ram’s-horn. Martynia louisianica P. Mill. • CT, MA, RI, VT; also reported from ME and NH by Kartesz (1999), but specimens are unknown. Fields, areas of cultivation.

Native to North America?

Yes and no (some introduced)

Sometimes confused with

Sesamum orientale:
flowers solitary in the axils of leaves, corolla 15–33 mm long, and fruit 2–3 cm long, tipped by a short, broad, straight beak that is ultimately split into two halves (vs. P. louisianica, with flowers in mostly 8- to 20-flowered racemes, corolla 35–55 mm long, nad fruit 10–20 cm long, tipped by long, arching, horn-like beak that is ultimately split into two halves).

Synonyms

  • Martynia louisianica P. Mill.

Family

Pedaliaceae

Genus

Proboscidea