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• Emex
• Emex spinosa

Emex spinosa — spiny threecorner-Jack

Facts

Spiny threecorner-Jack is native to Mediterranean Africa, but has made its way around the world. It has a patchy distribution in the U.S. and is known in New England only from a waste area in Massachusetts; but every state in which it occurs classifies it as a noxious weed. It gets its colorful name from its fruits, which have three spines that project out at the corners. In many warm climes, it can flower year-round, and is highly prolific.

Habitat

Anthropogenic (man-made or disturbed habitats)

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 growth after flowering

  • the calyx does not grow to cover or partially cover the fruit
  • the calyx grows to cover or partially cover the fruit

  Carpels fused

  the carpels are fused to one another

  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 lacks a hypanthium

  Flower petal color

  green to brown

  Flower reproductive parts

  the flower has either only pollen- or only seed-producing parts

  Flower symmetry

  there are two or more ways to evenly divide the flower (the flower is radially symmetrical)

  Flowers sunken into stem

  no

  Form of style

  • the flower has two or more completely separate styles
  • the style is narrow 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

  Hypanthium

  • the flower does not have a 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

  Nectar spur

  the flower has no nectar spurs

  Number of pistils

  1

  Number of sepals, petals or tepals

  • there are five petals, sepals, or tepals in the flower
  • there are six petals, sepals, or tepals in the flower

  Number of styles

  3

  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

  green to brown

  Petal appearance

  the petals are green and/or leafy in texture

  Petal folds or pleats

  the petals of the flower do not have folds or plaits

  Petal hairs (Viola)

  NA

  Petal number

  3

  Petal tips (Cuscuta)

  NA

  Reproductive system

  each flower has only carpels or only stamens, but both types of flower are present on each plant (monoecious)

  Scales inside corolla

  no

  Sepal and petal color

  the petals and sepals are similar

  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 features

  one or more sepals have a spine at the tip

  Sepal number

  3

  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 not attached to the petals or tepals

  Stamen number

  • 0
  • 4
  • 5
  • 6

  Stamen position relative to petals

  NA

  Stamens fused

  the stamens are not attached to one another

  Style petal-like

  the styles are not petal-like

  Umbel flower reproductive parts

  NA

  Upper lip of bilabiate corolla

  NA

• Fruits or seeds

  Achene surface (Polygonum)

  NA

  Achene type

  the fruit is an achene (dry, indehiscent, and usually one-seeded)

  Berry color

  NA

  Capsule color (Viola)

  NA

  Capsule ribs

  NA

  Capsule splitting

  NA

  Fruit (pyxis) dehiscence

  NA

  Fruit features (Brassicaceae)

  NA

  Fruit length

  4–5 mm

  Fruit locules

  one

  Fruit type (general)

  the fruit is dry but does not split open when ripe

  Fruit type (specific)

  the fruit is an achene (dry, usually one-seeded, does not separate or split open at maturity)

  Legumes (Fabaceae)

  NA

  Mericarp length

  0 mm

  Mericarp segment shape (Desmodium)

  NA

  Other markings on berry

  NA

  Ovary stipe

  the ovary or fruit does not have a stipe

  Placenta arrangement

  the plant has basal placentation, where one or a few ovules develop at the base of a simple or compound ovary

  Rows of seeds in fruit (Brassicaceae)

  NA

  Schizocarpic fruit compression

  NA

  Schizocarpic fruit segments

  0

  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 only a single year or less

  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

  there is a thickened taproot on the plant

• Leaves

  Bracteole number (Apiaceae)

  0

  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

  Hairs on underside of leaf

  the underside of the leaf is not hairy, or it has very few hairs

  Leaf arrangement

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

  Leaf blade edges

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

  Leaf blade length

  30–130 mm

  Leaf blade shape

  • the leaf blade is oblong (rectangular but with rounded ends)
  • the leaf blade is ovate (widest below the middle and broadly tapering at both ends)
  • the leaf blade is triangular, with the stalk or attachment point on one of the sides

  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 has outward-pointing teeth
  • the leaf blade margin has rounded teeth

  Leaf type

  the leaves are simple (lobed or unlobed but not separated into leaflets)

  Leaflet number

  0

  Leaves per node

  there is one leaf per node along the stem

  Pinnately compound leaf type

  NA

  Specific leaf type

  the leaves are simple (lobed or unlobed but not separated into leaflets)

  Stipels

  NA

  Stipule features

  • glabrous on the surface
  • the stipules do not have tiny hairs (cilia) at their tips

  Stipules

  the plant has stipules

• Place

  Habitat

  terrestrial

  New England state

  Massachusetts

  Specific habitat

  man-made or disturbed habitats

• Stem, shoot, branch

  Branched tendrils

  NA

  Hair between stem nodes

  the stem has no hairs between the nodes

  Hairs between stem nodes

  the stem has no hairs between the nodes

  Hooked hairs on stem between nodes

  no

  Leaves on stem

  there is at least one full leaf above the base of the flowering stem

  Plant height

  30–80 cm

  Tendril origin

  NA

  Tendrils

  the plant does not have tendrils

Wetland status

Not classified

New England distribution and conservation status

From the dichotomous key of Flora Novae Angliae