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• Oligoneuron rigidum

Oligoneuron rigidum — stiff flat-topped-goldenrod

Facts

Stiff flat-topped-goldenrod reaches the edge of its natural range in New England, where it is very rare, occurring historically in Massachusetts and Rhode Island, and currently found in only a few populations in Connecticut, on limestone ledges and on dry, sandy and rocky soils near the coast. Its flowering heads are large and few, compared to those of other goldenrod species. The main threats to New England populations include shading and competition from other plant species, and browsing by white-tailed deer.

Habitat

Forest edges

Characteristics

• Flowers

  Bract cycle number

  there are three or more cycles of bracts

  Bract outer side hair type

  • the bracts are hairy, with simple hairs on their outer surface
  • the bracts are not hairy on their outer surface

  Bract outer side hairs

  • the bracts are hairy on their outer surfaces
  • the bracts are not hairy on their outer surfaces

  Bract shape

  the main bracts are oblong (roughly rectangular but rounded at the ends)

  Bract spines

  the bracts have no spines

  Bract tip extension appearance

  NA

  Bract tip extension edge

  there are no projections from the bract tips

  Bract tip orientation

  the bracts are pressed against the plant, or spreading out at the tips

  Bract tip shape

  the tips of the bracts are rounded

  Bracts

  there are at least two distinct forms of bracts in different cycles

  Disk flower color

  white

  Disk flower lobe number

  5

  Disk flower number

  • 11-20
  • 21-50

  Disk flower reproductive parts

  the disk flower has both pollen- and seed-producing parts

  Disk flower shape

  the disk flower is abruptly widened at some point below the lobes

  Disk width

  5–10 mm

  Flower head number

  each flowering stem has four or more flower heads on it

  Flower head outer flowers

  at the outer edge of the flower head, each flower has a single enlarged lobe or strap

  Flower head platform

  the base has no bristles or papery scales

  Flower head platform surface

  NA

  Flower head position

  some or all the flower heads are grouped in clusters of two or more

  Flower head profile

  the disk is rounded across the top

  Flower head shape

  the sides of the flower head are roughly parallel, like a cylinder

  Flower head width

  anything

  Flower type in flower heads

  the flower head has tubular disk flowers in the center and ray flowers, these often strap-shaped, around the periphery

  Height of flower head base

  6–8 mm

  Inflorescence branching (Solidago)

  NA

  Inflorescence shape

  the inflorescence is flat-topped in profile

  Inflorescence stem

  • hairs are present on the stem of the inflorescence
  • the stem of the inflorescence is not hairy

  Number of bracts at flower head base

  10–35

  Ovary beak

  there is no beak on the ovary

  Ovary cross-section

  • the ovary has five or more corners in cross-section
  • the ovary is compressed (flattened)

  Ovary hair type

  the ovary has no hairs on it

  Ovary hairs

  the ovary has no hairs on it

  Ovary lines or ribs

  there are ten or more ribs visible on the ovary

  Ovary profile

  in profile, the ovary is another shape

  Peduncle hair type

  the hairs on the peduncles are simple (not branched), don’t have glands, and are not woolly

  Peduncle hairs

  the peduncles are hairy

  Peduncle length

  3–15 mm

  Peduncle orientation

  the flower heads are held upright, or slightly angled outwards

  Ray flower color

  yellow

  Ray flower reproductive parts

  the ray flowers have carpels or stamens, but not both

  Ray flowers

  • 11-15
  • 6-10

  Ray length

  3–5 mm

  Reproductive system

  some of the flowers on the plant have only carpels or stamens, while others have both carpels and stamens

  Scale tip

  NA

  Smaller bracts at base of bracts

  there is a cycle of much smaller bracts outside the cycle of larger and longer bracts

  Style branch number

  the style has two branches

  Width of flower head base

  5–7 mm

• Fruits or seeds

  Number of pappus parts

  11 or more

  Ovary length in developed fruit

  0.7–1.7 mm

  Seed hair tuft details

  the pappus hairs are hooked or barbed

  Seed hair tuft length

  3–4 mm

  Seed hair tuft tips

  the pappus hairs are slender

  Seed hairs uniform

  there are two distinct lengths of pappus hairs

  Seed tuft scale number

  0

  Seed tuft type

  the pappus is made of very fine hairs or bristles

  Top of disk flower ovary

  NA

  Tuft or plume on fruit

  at least a part of the plume is made up of fine bristles

• Glands or sap

  Leaf blade glands

  the leaf blades have glandular (translucent) dots or scales

  Sap

  the sap is clear and watery

• Growth form

  Growth form

  the plant has one or more free-standing stems

  Plant lifespan

  the plant is perennial, it shows evidence of previous year's leaves, stems or stem bases

  Spines on plant

  the plant has no spines

  Underground organs

  • the plant has a caudex (the root mass is firm and hardened at the top)
  • the plant has a rhizome (a horizontal underground stem with roots growing from it)

• Leaves

  Final leaf segment length (compound lvs only)

  0 mm

  Final leaf segment width (compound lvs only)

  0 mm

  Hairs on underside of leaf blade

  the underside of the leaf is fuzzy or hairy

  Hairs on upper side of leaf blade

  the upper side of the leaf is fuzzy or hairy

  Leaf arrangement

  • alternate: there is one leaf per node along the stem
  • basal: the leaves are growing only at the base of the plant

  Leaf blade base

  • the leaf has a distinct petiole
  • the leaf has no petiole
  • the leaf has no petiole and at the base it clasps the stem, or goes all the way around the stem so the stem appears to pierce the leaf

  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

  Leaf blade bloom

  the underside of the leaf has no noticeable bloom

  Leaf blade edges

  the edge of the leaf blade has teeth

  Leaf blade flatness

  the leaf is flat (planar) at the edges

  Leaf blade hairs

  the leaf blade has simple hairs with no glands, and not tangled or wooly

  Leaf blade length

  60–300 mm

  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)
  • the leaf blade is ovate (widest below the middle and broadly tapering at both ends)

  Leaf blade surface colors

  there is no noticeable color variation on the upper surface of the leaf

  Leaf blade tip

  • the tip of the leaf blade is acute (sharply pointed)
  • the tip of the leaf blade is obtuse (bluntly pointed)

  Leaf blade veins

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

  Leaf blade width

  15–100 mm

  Leaf disposition

  the lower leaves are larger, toothier, and/or on longer stalks than the upper leaves

  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 tufts in axils

  there are no clusters of smaller leaves

  Leaf type

  leaves are simple (i.e., lobed or unlobed but not separated into leaflets)

  Leaflet number

  0

  Specific leaf type

  the leaves are simple (i.e., lobed or unlobed but not separated into leaflets

• Place

  Habitat

  terrestrial

  New England state

  • Connecticut
  • Massachusetts
  • Rhode Island

  Specific habitat

  edges of forests

• Stem, shoot, branch

  Flowering stem cross-section

  the flowering stem is circular, or with lots of small angles

  Leaves on stem

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

  Stem internode hair direction

  the hairs point mostly upwards to outwards

  Stem internode hair type

  the hairs on the stem are plain, without glands or branches, and not tangled

  Stem internode hairs

  the stem has hairs between the nodes

Wetland status

Not classified

New England distribution and conservation status

From the dichotomous key of Flora Novae Angliae