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Native Plant Trust: Go Botany Discover thousands of New England plants

Nabalus racemosus — glaucous rattlesnake-root

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Facts

Glaucus rattlesnake-root is found in a wide swath from Alberta to Quebec, Canada, south as far as Colorado and New Jersey. It almost completely skips over New England, with the exception of Northern Maine, where it is rare and confined to high-pH, rocky, ledgy and gravelly river shores.

Habitat

Shores of rivers or lakes

New England distribution

Adapted from BONAP data

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North America distribution

Adapted from BONAP data

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Characteristics

Habitat
terrestrial
New England state
Maine
Leaf type
leaves are simple (i.e., lobed or unlobed but not separated into leaflets)
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 edges
  • the edge of the leaf blade has no teeth or lobes
  • the edge of the leaf blade has teeth
Flower type in flower heads
the flower head has ray flowers only, meaning all of the individual flowers of the flower head have a strap-shaped ray, which may or may not have teeth at the very tip of the ray
Ray flower color
  • blue to purple
  • pink to red
  • white
Tuft or plume on fruit
at least a part of the plume is made up of fine bristles
Spines on plant
the plant has no spines
Leaf blade length
40–250 mm
Disk flower number
NA
Show all characteristics

  • Flowers

    Bases of bract appendages
    NA
    Bract color
    • the bracts are colored, or at least tinged with, pink, red or purple
    • the bracts are not colored or tinged with pink, red or purple
    Bract cycle number
    there is one main cycle of bracts
    Bract outer side hair type
    the bracts are hairy, with simple hairs on their outer surface
    Bract outer side hairs
    the bracts are hairy on their outer surfaces
    Bract shape
    • the main bracts are lanceolate (widest above the base, then taper narrowly towards the tip)
    • the main bracts are linear (long and very narrow)
    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 shape
    the tips of the bracts acute (have a sharp point)
    Bracts
    the bracts in separate cycles are similar or gradually changing from the outer to inner cycles
    Disk flower color
    NA
    Disk flower lobe number
    NA
    Disk flower number
    NA
    Disk flower proportions
    NA
    Disk flower reproductive parts
    NA
    Disk flower shape
    NA
    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 type in flower heads
    the flower head has ray flowers only, meaning all of the individual flowers of the flower head have a strap-shaped ray, which may or may not have teeth at the very tip of the ray
    Height of flower head base
    10–12 mm
    Inflorescence branching (Solidago)
    NA
    Inflorescence shape
    the inflorescence is not flat-topped but appears rounded, with some flower heads distinctly higher than others
    Number of bracts at flower head base
    7–14
    Ovary beak
    • there is a beak on the ovary
    • there is no beak on the ovary
    Ovary cross-section
    the ovary has five or more corners in cross-section
    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 seven to nine ribs visible on the ovary
    • there are ten or more ribs visible on the ovary
    Ovary profile
    in profile, the ovary is oblong (roughly rectangular but rounded at the ends)
    Ovary surface
    the ovary surface has no points, bumps or wrinkles, though it may have lines, ribs or wings
    Ray flower color
    • blue to purple
    • pink to red
    • white
    Ray flower reproductive parts
    the ray flowers have both carpels and stamens
    Ray flowers
    • 11-15
    • 16-25
    • 26-50
    • 6-10
    Ray length
    7–13 mm
    Reproductive system
    NA
    Scale tip
    NA
    Smaller bracts at base of bracts
    there is no smaller, outer cycle of bracts
    Swelling at base of flower head
    the peduncles are not swollen, or only slightly
    Width of flower head base
    2–14 mm

  • Fruits or seeds

    Number of pappus parts
    11 or more
    Ovary length in developed fruit
    5–6 mm
    Seed hair tuft color
    the pappus hairs are another color
    Seed hair tuft details
    the pappus hairs are hooked or barbed
    Seed hair tuft length
    6–7 mm
    Seed hair tuft tips
    the pappus hairs are slender
    Seed tuft type
    the pappus is made of very fine hairs or bristles
    Tuft or plume on fruit
    at least a part of the plume is made up of fine bristles

  • Glands or sap

    Sap
    the sap is milky and opaque, and may be white or colored

  • 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 one or more swollen storage organs underground, such as bulbs, tubers or corms
    • there is a thickened taproot on the plant

  • 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 not hairy, or has very few hairs
    Hairs on upper side of leaf blade
    the upper side of the leaf is not hairy, or has very few hairs
    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
    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
    • the edge of the leaf blade has teeth
    Leaf blade hairs
    NA
    Leaf blade length
    40–250 mm
    Leaf blade shape
    • the leaf blade is oblanceolate (lance-shaped, but with the widest point above the middle of the leaf blade)
    • the leaf blade is obovate (egg-shaped, but with the widest point above the middle of the leaf blade)
    Leaf blade tip
    • the tip of the leaf blade is obtuse (bluntly pointed)
    • the tip of the leaf blade is rounded, with no point
    Leaf blade veins
    the leaf blade has one main vein running from the base towards the tip
    Leaf blade width
    10–80 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 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
    Maine
    Specific habitat
    shores of rivers or lakes

  • Stem, shoot, branch

    Leaves on stem
    there is at least one full leaf above the base of the flowering stem
    Stem bloom
    the stem has a powdery or waxy film on it that can be rubbed away
    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
    • the stem has no hairs between the nodes
    Stem internode hairs
    • the stem has hairs between the nodes
    • the stem has no hairs between the nodes

Wetland status

Usually occurs in wetlands, but occasionally in non-wetlands. (Wetland indicator code: FACW)

In New England

Distribution

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

Conservation status

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

Maine
uncommon (S-rank: S3), special concern (code: SC)
Vermont
unrankable (S-rank: SU)

From Flora Novae Angliae dichotomous key

4.  Nabalus racemosus (Michx.) Hook. NC

glaucous rattlesnake-root. Harpalyce racemosa (Michx.) D. Don ex Beck; Prenanthes racemosa Michx.; P. racemosa Michx. ssp. multiflora Cronq.; P. racemosa Michx. var. multiflora (Cronq.) Cronq. • ME; northern portion of state. Ice-scoured river shores in high-pH bedrock and/or 
till regions.

4×6. Nabalus racemosus × Nabalus trifoliolatus → Nabalus ×‌mainensis (Gray) Heller is a rare hybrid known from only northern Maine river shores within New England. It ± resembles N. racemosus vegetatively (including the clasping upper stem leaves), but the basal leaf blades are more abruptly contracted to a petiole-like base, and the involucral bracts are glabrous (as in N. trifoliolatus).

Native to North America?

Yes

Sometimes confused with

Nabalus serpentarius:
lower leaf blades pinnately or palmately lobed or simple and then ovate to elliptic, the middle and upper blades short-petioled or sessile, but not clasping, and capitulescence broader, corymb- or panicle-like (vs. N. racemosus, with lower leaf blades simple, broad-oblanceolate to obovate, the middle and upper blades clasping, and capitulescence tall and narrow, raceme-like).

Synonyms

  • Harpalyce racemosa (Michx.) D. Don ex Beck
  • Prenanthes racemosa Michx.
  • Prenanthes racemosa Michx. ssp. multiflora Cronq.
  • Prenanthes racemosa Michx. var. multiflora (Cronq.) Cronq.

Family

Asteraceae

Genus

Nabalus