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Desmodium sessilifolium — sessile-leaved tick-trefoil

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Facts

Sessile-leaved tick-trefoil is at the northeastern limit of its range in New England, and is very rare in our region. The slightly misleading name refers not to the absence of petioles, but to the very short petioles (1-3 mm in most cases) possessed by this species.

Habitat

Anthropogenic (man-made or disturbed habitats), meadows and fields, sandplains and barrens

New England distribution

Adapted from BONAP data

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

North America distribution

Adapted from BONAP data

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Characteristics

Habitat
terrestrial
Flower petal color
  • blue to purple
  • pink to red
Leaf type
the leaves are compound (made up of two or more discrete leaflets
Leaf arrangement
alternate: there is one leaf 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
  • 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
10
Fruit type (general)
the fruit is dry but does not split open when ripe
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 is only one way to evenly divide the calyx (the calyx is bilaterally symmetrical)
    Carpels fused
    • NA
    • the carpel is solitary or (if 2 or more) the carpels are not 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 a hypanthium
    Flower length
    Up to 5 mm
    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 narrow at the tip and unbranched
    Fused stamen clusters
    there are two clusters of fused stamens
    Fusion of sepals and petals
    the petals or the sepals are fused into a cup or tube
    Hairs on flower stalk
    the flower stalk has hairs on it
    Hairs on inflorescence
    the axis of the inflorescence has hairs entirely without glands
    Horns in hoods (Asclepias)
    NA
    Hypanthium
    the flower has 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
    Interior flower disk
    the flower does not have an interior disc
    Length of flower stalk
    1.5–4.5 mm
    Nectar spur
    the flower has no nectar spurs
    Number of carpels
    1
    Number of pistils
    1
    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
    • pink to red
    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 arranged in a cycle with edges overlapping like roof shingles (imbricate)
    Petal folds or pleats
    • the petals of the flower do not have folds or plaits
    • the petals of the flower have folds or plaits on them
    Petal hairs (Viola)
    NA
    Petal length
    4–6 mm
    Petal length relative to sepals
    the petals are longer than the sepals
    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
    green to brown
    Sepal number
    4–5
    Sepal orientation
    the sepals are slightly curved outwards from the corolla
    Sepal relative length
    the sepal lobes are longer than the fused portion
    Sepal texture
    the sepals are either very thin but flexible, like a membrane, or they are leaf-like in texture
    Sepal uniformity
    one or more of the sepals is much narrower or shorter than the others
    Sepals fused only to sepals
    the sepals are fused to each other (not other flower parts), at least near their bases
    Stamen morphology
    the stamens within each cycle are the same
    Stamen number
    10
    Stamens fused
    the stamens are attached to one another at or near their bases
    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

  • 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
    • the capsule splits by two main valves, teeth or pores
    Fruit (pyxis) dehiscence
    NA
    Fruit cross-section
    the fruit is at least somewhat flattened
    Fruit features (Brassicaceae)
    NA
    Fruit locules
    one
    Fruit shape
    the fruit is flat or strongly compressed
    Fruit stalk orientation
    the fruits point upward or spread or curve outward
    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)
    Hair type on fruit
    the hairs on the fruits are simple (not branched), don’t have glands, and are not woolly
    Hairs on fruit
    the fruits have hairs on them
    Legumes (Fabaceae)
    the legume has none of the mentioned special features
    Mericarp length
    4–6.5 mm
    Mericarp segment shape (Desmodium)
    the mericarp is rounded on the lower margin
    Other markings on berry
    NA
    Ovary stipe
    the ovary or fruit has a stipe
    Ovary stipe length
    1–3 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
    the fruit is flattened perpendicular to the commissure
    Schizocarpic fruit segments
    1–3
    Seed number
    1–3
    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)
    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
    Plants darken when dry
    no
    Spines on plant
    the plant has no spines
    Underground organs
    NA

  • Leaves

    Bracteole number (Apiaceae)
    0
    Bracteoles
    there are no bracteoles on the plant
    Bracts in plantain (Plantago)
    NA
    Final leaf segment length (compound lvs only)
    30–70 mm
    Final leaf segment length to width ratio (compound lvs only)
    3–10
    Final leaf segment width (compound lvs only)
    5–15 mm
    Floral bracts
    the flower has one or more bracts associated with 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
    Hooked hairs on underside of leaf
    yes
    Leaf arrangement
    alternate: there is one leaf per node along the stem
    Leaf blade base
    • the leaf has a distinct leaf stalk (petiole)
    • the leaf has no stalk
    Leaf blade base shape
    the base of the leaf blade is rounded
    Leaf blade base symmetry
    the leaf blade base is symmetrical
    Leaf blade edges
    the edge of the leaf blade is entire (has no teeth or lobes)
    Leaf blade hairs
    the leaf blade has simple hairs with no glands, and not tangled or wooly
    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 oblong (rectangular but with rounded ends)
    Leaf blade surface colors
    the upper side of the leaf blade is relatively uniform in color
    Leaf blade texture
    the leaf blade is coriaceous (has a firm, leathery texture)
    Leaf blade vein pattern
    the major veins form a net-like pattern due to splitting and rejoining
    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 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
    • the hairs are flat against the leaf surface, mostly pointing towards the leaf tip
    • the hairs are standing up straight or curved in different directions
    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 leaf stalks
    • the leaves have no leaf stalks, but attach directly to the stem
    Leaf stalk attachment to leaf
    the petiole attaches at the basal margin of the leaf blade
    Leaf stalk base
    the petiole base is narrow where it attaches to the stem
    Leaf stalk length
    1–4 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 type
    the leaves are compound (made up of two or more discrete leaflets
    Leaf types
    There is a gradual change in appearance of the leaves from the base (or near the base) of the plant to those from further up on the stem, with leaves progressively changing as one moves higher on the stem (often becoming shorter, or less toothed/lobed, and/or with shorter petioles).
    Leaf variation
    the leaves are nearly similar in size, prominence of teeth, and length of stalks throughout the stem
    Leaflet number
    1–3
    Leaflet petiolules
    the leaflets of the compound leaf have petiolules
    Leaves per node
    there is one leaf per node along the stem
    Pinnately compound leaf type
    the pinnately compound leaves have a terminal leaflet (and usually have an odd number of leaflets per axis)
    Specific leaf type
    the leaf has a row of two or more lobes on each side of the central axis
    Stipels
    the petiolules have stipels at their bases
    Stipule features
    NA
    Stipule length
    3–5 mm
    Stipule shape
    the stipules are lanceolate (lance-shaped; widest below the middle and tapering at both ends)
    Stipules
    the plant has stipules
    Teeth per side of leaf blade
    0

  • Place

    Habitat
    terrestrial
    Specific habitat
    • man-made or disturbed habitats
    • meadows or fields
    • sandplains or barrens

  • 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
    Flowering stem cross-section
    the flowering stem is circular, or with lots of small angles so that it is roughly circular
    Hair between stem nodes
    the stem has hairs between the nodes
    Hairs between stem nodes
    the hairs on the stem are plain, without glands or branches, and not tangled
    Hooked hairs on stem between nodes
    yes
    Leaves on stem
    there is at least one full leaf above the base of the flowering stem
    Plant height
    60–150 cm
    Stem bloom
    there is no powdery or waxy film on the stem
    Stem nodes swollen
    the stem is not swollen at the nodes
    Stem orientation
    the stems are upright or angled outwards
    Stem spacing
    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

Wetland status

Not classified

In New England

Distribution

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

Conservation status

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

Connecticut
historical (S-rank: SH), special concern, extirpated (code: SC*)
Massachusetts
historical (S-rank: SH)
Rhode Island
extremely rare (S-rank: S1), state threatened (code: ST)

From Flora Novae Angliae dichotomous key

11.  Desmodium sessilifolium (Torr. ex M.A. Curtis) Torr. & Gray NC

sessile-leaved tick-trefoil. Hedysarum sessilifolium Torr. ex M.A. Curtis; Meibomia sessilifolia (Torr. ex M.A. Curtis) Kuntze • CT, MA, RI. Dry, open, sandy areas, including roadsides and banks.

Native to North America?

Yes

Sometimes confused with

Desmodium paniculatum:
schizocarps with 3-6 triangular segments, petioles 15-50 mm long, and leaflets herbaceous and inconspicuously veined (vs. D. sessilifolium, with schizocarps with 1-3 semicircular segments, petioles 1-4 mm long, and leaflets subcoriaceous and conspicuously reticulate-veined).

Synonyms

  • Hedysarum sessilifolium Torr. ex M.A. Curtis
  • Meibomia sessilifolia (Torr. ex M.A. Curtis) Kuntze

Family

Fabaceae

Genus

Desmodium