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• Dichotomous Key
• Fabaceae
• Robinia
• Robinia hispida

Robinia hispida — bristly locust

Facts

Bristly locust is a 2-10 foot (0.7-3.5m) tall shrub, native to southeastern North America and introduced in other areas including New England. It is also called rose acacia for its showy sprays of pink, pea-like flowers. Its stems and seed pods are bristly and purple. It spreads abundantly by suckering, and as such, is useful as a hedge or screen and for reclaiming eroded sites. It is vulnerable to breakage and a variety of diseases, however, so it must be tended carefully.

Habitat

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

Characteristics

• Buds or leaf scars

  Bud position relative to scar

  the winter bud has a leaf scar partially or completely surrounding it

  Bud scale number

  there are no scales on the winter buds

  Bud scar shape (Fraxinus)

  NA

  Collateral buds

  there are no collateral buds on the sides of the branches

  Leaf scar arrangement

  there is one leaf scar per node on the stem or twig

  Superposed buds

  • there are no superposed buds on the branch
  • there are superposed buds above the main (terminal) bud

  Winter bud stalks

  the winter buds have no stalks

• Flowers

  Carpels fused

  the carpel is solitary or (if 2 or more) the carpels are not fused to one another

  Enlarged sterile flowers

  there are no enlarged sterile flowers on the plant

  Flower petal color

  • pink
  • purple
  • red

  Flower symmetry

  there is only one way to evenly divide the flower (the flower is bilaterally symmetrical)

  Hairs on ovary (Amelanchier)

  NA

  Hypanthium present

  the flower has a hypanthium

  Inflorescence hairs

  there are hairs on some part of the inflorescence

  Inflorescence position

  the inflorescences grow on the twigs

  Inflorescence type

  the inflorescence is a raceme (a long unbranched stem with stalked flowers growing along it)

  Number of pistils

  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 appearance

  the petals are thin and delicate, and pigmented (colored other than green or brown)

  Petal fusion

  • the perianth parts are fused to form a tube, cup, or bell shape
  • the perianth parts are separate

  Sepal cilia (Ilex)

  NA

  Sepal tip glands

  there are no glands at the tips of the sepal lobes

  Sepals fused only to sepals

  the sepals are fused to each other (not other flower parts), at least near their bases

  Stamen number

  10

  Stamen position relative to petals

  NA

  Stamens fused

  the stamens are fused to one another at or near their bases

• Fruits or seeds

  Berry color

  NA

  Fruit tissue origin

  • the hypanthium of the flower becomes part of the fruit
  • there are no flower parts that form part of the fruit

  Fruit type (general)

  the fruit is dry and splits open when ripe

  Fruit type (specific)

  legume

  Nut with spines (Fagaceae)

  NA

  Wings on fruit

  there are no wings on the fruit

• Glands or sap

  Sap color

  the sap is clear and watery

  Stalked glands on fruit (Rosa)

  NA

• Growth form

  Growth form

  the plant is a shrub (a woody plant with several stems growing from the base)

• Leaves

  Hairs on underside of leaf blade

  the underside of the leaf has no hairs

  Hairs on upper side of leaf blade

  the upper side of the leaf is not hairy, or has very few hairs

  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
  • the base of the leaf blade is truncate (ends abruptly in a more or less straight line as though cut off)

  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 has no teeth or lobes

  Leaf blade edges (Acer)

  NA

  Leaf blade flatness

  the leaf is flat (planar) at the edges

  Leaf blade hairs

  the hairs on the leaf blade are different from the choices given

  Leaf blade length

  150–300 mm

  Leaf blade scales

  there are no scales on the leaf blades

  Leaf blade shape

  • the leaf blade is oblong (rectangular but with rounded ends)
  • the leaf blade is orbicular (roughly circular, as wide as long)
  • the leaf blade is ovate (widest below the middle and broadly tapering at both ends)

  Leaf blade texture

  the leaf blade is herbaceous (has a leafy texture)

  Leaf blade translucent dots

  there are no translucent dots on the leaf blade

  Leaf blade vein pattern

  the main veins of the leaf blade are pinnate (the secondary veins branch off at intervals from the main central vein) and non-arcuate (not arched towards the leaf tip)

  Leaf blade veins

  the leaf blade has one main vein running from the base toward the tip

  Leaf duration

  the leaves drop off in winter (or they wither but persist on the plant)

  Leaf form

  the plant is broad-leaved (with broadly flattened leaf blades)

  Leaf lobe tips (Quercus)

  NA

  Leaf midrib glands

  the midrib of the leaf blade lacks glands on the upper surface

  Leaf stalk

  the leaves have leaf stalks

  Leaf stalk attachment to leaf

  the petiole attaches at the basal margin of the leaf blade

  Leaf stalk nectaries

  there are no nectaries on the leaf stalk

  Leaf stalk shape

  the leaf stalk is not flattened

  Leaf teeth

  the edge of the leaf blade is entire (has no teeth or lobes)

  Leaf teeth hairs (Carya)

  NA

  Leaf type

  the leaf blade is compound (made up of two or more discrete leaflets

  Leaves per node

  there is one leaf per node along the stem

  Specific leaf type

  the leaf is compound, with a single terminal leaflet and more than two additional leaflets

  Stipules

  there are no stipules on the plant, or they fall off as the leaf expands

• Place

  Habitat

  terrestrial

  New England state

  • Connecticut
  • Maine
  • Massachusetts
  • New Hampshire
  • Rhode Island
  • Vermont

  Specific habitat

  • man-made or disturbed habitats
  • meadows or fields

• Scent

  Plant odor

  the plant does not have much of an odor, or it has an unpleasant or repellant odor

• Stem, shoot, branch

  Aerial roots

  the plant has no aerial roots

  Bark texture

  the bark of an adult plant is thin and smooth

  Branch brittleness (willows only)

  NA

  Branch cross-section

  the branch is circular in cross-section, or it has five or more sides, so that there are no sharp angles

  First-year cane (Rubus)

  NA

  Lenticels on twigs

  there are clearly lenticels on the twigs

  Pith shape

  the outline of the pith in a twig is roughly round

  Short shoots

  there are no peg- or knob-like shoots present

  Twig bloom

  there is no bloom on the twig

  Twig hairs

  the twigs have hairs with glands at their tips

  Twig papillae (Vaccinium species only)

  NA

  Twig scales

  there are no scales on the twig surface

  Twig winter color

  • brown
  • gray
  • red

  Wings on branch

  the branch does not have wings on it

  armature on plant

  • the plant does not have spines, prickles, or thorns
  • the plant has spines, prickles, or thorns

Wetland status

Not classified

New England distribution and conservation status

From the dichotomous key of Flora Novae Angliae