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Dryopteris clintoniana — Clinton's wood fern

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New England distribution

Adapted from BONAP data

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North America distribution

Adapted from BONAP data

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Facts

Clinton's wood fern is a fertile hybrid between crested wood fern (Dryopteris cristata) and Goldie's fern (D. goldiana). Its pinnae (leaflets) are twisted , so the leaf does not appear flat.

Habitat

Forests, wetland margins (edges of wetlands)

Characteristics

Habitat
  • terrestrial
  • wetlands
New England state
  • Connecticut
  • Maine
  • Massachusetts
  • New Hampshire
  • Rhode Island
  • Vermont
Leaf divisions
  • the leaf blade is compound (divided into leaflets)
  • the leaf blade is twice compound (divided into leaflets, which are further divided into leaflets)
Plant growth form
the leaves grow from a rhizome growing at or below the ground
Spore-bearing leaflets
the spore-bearing fronds are slightly different from the sterile fronds
Sorus shape
the sori are circular or kidney-shaped
Leaf stalk scales
the leaf stalk has scales
Leaf stalk hairs
there are no hairs on the leaf stalk
Leaf blade length
30–60 cm
Leaf vein tips
the veins end in small round expanded areas, and do not reach the edge of the leaf blade
Show all characteristics

  • Growth form

    Life form
    the plant is herbaceous and terrestrial
    Life stage
    the plant is visible as a typical leaf-bearing fern (sporophyte)
    Spore-bearing leaflets
    the spore-bearing fronds are slightly different from the sterile fronds

  • Leaves

    Features of leaves
    there are no special features on the leaves
    Leaf blade length
    30–60 cm
    Leaf blade shape
    the leaf blades are widest above the base, then taper narrowly towards the tip (lanceolate)
    Leaf blade tip shape
    the tip of the leaf blade is a blunt point (obtuse)
    Leaf blade width
    At least 10 cm
    Leaf divisions
    • the leaf blade is compound (divided into leaflets)
    • the leaf blade is twice compound (divided into leaflets, which are further divided into leaflets)
    Leaf lifespan
    the leaves remain green all year round, or are green in winter
    Leaf stalk color
    yellow to brown
    Leaf stalk hairs
    there are no hairs on the leaf stalk
    Leaf stalk length
    Up to 350 mm
    Leaf stalk relative length
    • the leaf stalk is more than a quarter, but less than three quarters as long as the blade
    • the leaf stalk is up to a quarter as long as the blade
    Leaf stalk scale location
    • the scales are present on both the lower and upper halves of the leaf stalk
    • the scales are present only on the lower half of the leaf stalk
    Leaf stalk scales
    the leaf stalk has scales
    Leaf stalk vessels
    3 to 9 bundles
    Leaf vein branching
    the secondary veins of the leaf blade branch dichotomously (two equal branches at each branch point)
    Leaf vein tips
    the veins end in small round expanded areas, and do not reach the edge of the leaf blade
    Leaflet relative size
    the bottom leaflets are about half as long as, to slightly longer than, the leaflets from the middle of the frond
    Leaflet stalks
    the leaflets are stalked
    Lobe or leaflet length
    70–110 mm
    Lobe or leaflet pairs
    10–15
    Lobe or leaflet shape
    • the lobe or leaflet is rectangular but with rounded ends (oblong)
    • the lobe or leaflet is widest below the middle and tapering at both ends; lance-shaped
    Lobe or leaflet width
    20–40 mm
    Plant growth form
    the leaves grow from a rhizome growing at or below the ground
    final leaf segment margin
    the topmost lobe or leaflet of the leaf blade has an edge with teeth tipped with bristles

  • Place

    Habitat
    • terrestrial
    • wetlands
    New England state
    • Connecticut
    • Maine
    • Massachusetts
    • New Hampshire
    • Rhode Island
    • Vermont
    Specific habitat
    • edges of wetlands
    • forests

  • Spores or spore cones

    Sorus features
    there are no special features on the sorus
    Sorus shape
    the sori are circular or kidney-shaped
    Sporangia location
    the spores are clustered on sori on the lower surface of the leaf blade
    Sporangium type
    the sporangia are opaque without an annulus and usually without a stalk (leptosporangiate)
    Spore forms
    there is only one type of spore present

Wetland status

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

New England distribution and conservation status

Distribution

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

Conservation status

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

Massachusetts
fairly widespread (S-rank: S4)

Native to North America?

Yes

Sometimes confused with

Dryopteris cristata:
basal leaflets triangular to broad-triangular and fertile leaves larger and more upright than vegetative leaves (vs. D. clintoniana, with basal leaflets narrow-triangular to oblong-triangular and fertile leaves relativley similar to vegetative leaves).

Synonyms

  • Aspidium cristatum (L.) Sw. var. clintonianum D.C. Eat. in Gray
  • Dryopteris cristata (L.) Gray var. clintoniana (D.C. Eat.) Underwood

Family

Dryopteridaceae

Genus

Dryopteris

Help

From the dichotomous key of Flora Novae Angliae

3.  Dryopteris clintoniana (D.C. Eat.) Dowell N

Clinton’s wood fern. Aspidium cristatum (L.) Sw. var. clintonianum D.C. Eat. in Gray; 
 Dryopteris cristata (L.) Gray var. clintoniana (D.C. Eat.) Underwood • CT, MA, ME, NH, RI, VT. 
Wet-mesic to hydric forests and swamp margins.

2×3. Dryopteris carthusiana × Dryopteris clintoniana → Dryopteris ×‌benedictii Wherry is a rare wood fern hybrid known from CT, MA, NH, VT. It shows leaf blades mostly 2.5 times divided near base with ± parallel margins and an abrupt apical taper, no stipitate glands on the indusia, and sori positioned midway between the midvein and margin.

3×4. Dryopteris clintoniana × Dryopteris cristata → This rare hybrid wood fern is known from CT, MA, ME, NH, VT. It may be more common than collections indicate but it is very difficult to determine due to the morphological similarity of its parent taxa. From Dryopteris clintoniana this hybrid differs in its triangular leaflets twisted parallel to the horizon and relatively narrow leaf 
blade. From D. cristata this hybrid differs in its relatively abrupt apical taper of the leaf 
blade and often shows a moderately dark brown interior region on the petiole scales.

3×5. Dryopteris clintoniana × Dryopteris filix-mas → This very rare wood fern hybrid is known from VT. It generally resembles Dryopteris clintoniana but has scales of two sizes on the petiole and some microscales on the costules. It can be separated from D. filix-mas by the relative paucity of scales on the rachis and costules and the relatively broader leaflets (lanceolate to triangular-lanceolate vs. narrow-lanceolate or narrow-triangular-lanceolate in D. filix-mas).

3×7. Dryopteris clintoniana × Dryopteris goldiana → Dryopteris ×‌mickelii Peck is a rare, though sometimes locally frequent, 
wood fern hybrid known from MA, ME, VT. It could be confused with a robust D. clintoniana. However, unlike that species, this hybrid has oblong lower leaflets, petiole scales with dark brown central regions, and often slightly curved leafules (rather than long-triangular to oblong-triangular lower leaflets, petiole scales commonly light brown, 
and ± straight leafules).

3×8. Dryopteris clintoniana × Dryopteris intermedia → Dryopteris ×‌dowellii (Farw.) Wherry is an infrequent wood fern hybrid known from CT, MA, ME, NH, VT. It resembles D. ×boottii (4 ×8) in many features but has broader leaf blades with a more abrupt taper at the apex.

3×9. Dryopteris clintoniana × Dryopteris marginalis → Dryopteris ×‌burgessii Boivin is a rare wood fern hybrid known from CT, MA, NH, VT. It is similar to D. ×slossoniae. However, the leaflets of D. ×burgessii are not as widely spaced on the rachis, the leaf blades are relatively wider, and the apex of the blade tapers more abruptly.