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• Isotrema macrophyllum

Isotrema macrophyllum — large-leaved Dutchman's pipe

Facts

The big, heart-shaped leaves and curving, tubular flowers make Large-leaved Dutchman's pipe quite distinctive among garden lianas. Native to the southeastern U. S., most plants found in New England are likely garden escapes. This plant is the main food source for caterpillars of the highly specialized, iridescent blue pipe-vine swallowtail butterfly (Battus philenor philenor). By ingesting the poisonous compounds in Dutchman's pipe leaves, the larvae become toxic to predators. Several other non-poisonous swallowtail butterfly species have evolved similar coloration to mimic this species and fool would-be predators.

Habitat

Forest edges, forests

Characteristics

• Buds or leaf scars

  Bud scale number

  there are two scales on the winter bud, and their edges meet

  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 superposed buds above the main (terminal) bud

• Flowers

  Carpels fused

  the carpels are fused to one another

  Enlarged sterile flowers

  there are no enlarged sterile flowers on the plant

  Flower petal color

  NA

  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 does not have a hypanthium

  Inflorescence hairs

  there are no hairs on the inflorescence

  Inflorescence type

  • the flowers grow out of the axil (point where a branch or leaf is attached to the main stem)
  • the inflorescence has only one flower on it

  Number of pistils

  1

  Ovary position

  the ovary is below the point of petal and/or sepal attachment

  Petal and sepal arrangement

  the flower includes only one cycle of petals or sepals

  Petal appearance

  NA

  Petal fusion

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

  Sepal appearance

  the sepals resemble petals in color and texture

  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

  6

  Stamen position relative to petals

  NA

• Fruits or seeds

  Berry color

  NA

  Fruit tissue origin

  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)

  the fruit is a capsule (splits along two or more seams, apical teeth or pores when dry, to release two or more seeds)

  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 liana (a woody plant with a vine-like growth form)

• Leaves

  Hairs on underside of leaf blade

  • the underside of the leaf has hairs on it
  • 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 cordate (heart-shaped, with rounded lobes)

  Leaf blade base symmetry

  the leaf blade base is symmetrical

  Leaf blade bloom

  there is a noticeable powdery or waxy bloom on the underside of the leaf

  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

  70–340 mm

  Leaf blade scales

  there are no scales on the leaf blades

  Leaf blade shape

  • the leaf blade is elliptic (widest near the middle and tapering at both 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 coriaceous (has a firm, leathery texture)
  • the leaf blade is membranaceous (thin, flexible, almost translucent)

  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 palmate (radiate out from the base, like a hand)

  Leaf blade veins

  the leaf blade has three or more main veins running from the base (or near the base) towards the tip

  Leaf blade width

  100–350 mm

  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 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 simple (lobed or unlobed but not separated into leaflets)

  Leaves per node

  there is one leaf per node along the stem

  Specific leaf type

  the leaves are simple (lobed or unlobed but not separated into 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
  • Vermont

  Specific habitat

  • edges of forests
  • forests

• Scent

  Plant odor

  the plant has a pleasantly aromatic odor

• Stem, shoot, branch

  Aerial roots

  the plant has no aerial roots

  Bark texture

  the bark of an adult plant is ridged or plated

  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 no lenticels on the twigs, or they are very hard to see

  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 few or no hairs on them

  Twig papillae (Vaccinium species only)

  NA

  Twig scales

  there are no scales on the twig surface

  Twig winter color

  brown

  Wings on branch

  the branch does not have wings on it

  armature on plant

  the plant does not have spines, prickles, or thorns

Wetland status

Not classified

New England distribution and conservation status

From the dichotomous key of Flora Novae Angliae