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Fuirena pumila — dwarf umbrella-sedge

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Facts

Dwarf umbrella-sedge is a coastal plain species of pond shores and low areas, found in Connecticut, Massachusetts, and Rhode Island. It is rare in Massachusetts and Rhode Island, as demands for water by rapidly growing towns alter the hydrology of its fragile ponshore habitats. Its common name refers both to the umbrella-shaped clusters of spikes borne atop its slender stems, and to the unusual, expanded scales that overtop its tiny seeds (achenes).

Habitat

Lacustrine (in lakes or ponds), 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
  • aquatic
  • wetlands
New England state
  • Connecticut
  • Massachusetts
  • Rhode Island
Stem shape in cross-section
the stem is roughly triangular in cross-section
Leaf blade width
3–5 mm
Leaf blade cross-section
the leaf blade is flat or rolled in at the edges
Inflorescence position
  • the inflorescence emerges from an axil, or most of its parts do so
  • the inflorescence is at the tip of the plant
Inflorescence branching
  • the inflorescence is branched
  • the inflorescence is on one or more stems with no branches
Fruit type (general)
the fruit is like a seed, and surrounded by scales
Fruit length
0.6–1 mm
Leaf position on plant
some leaf attachment points are above the midpoint of the stem
Perianth composition
there are three bristles and three scales on narrow stalks, attached at the base of the achene
Fruit cross-section
the fruit is triangular to terete (circular) in cross-section
Show all characteristics

  • Flowers

    Anther length
    0.5–0.7 mm
    Floral bristle color
    the bristles are pale brown to brown
    Floral bristle number
    1-4
    Floral bristle relative length
    the bristles are longer than the achene
    Floral bristles
    the bristles are straight or slightly curved
    Floral scale hairs
    the floral scales have hairs on them
    Floral scale length
    2.5–3 mm
    Floral scale nerves
    2-5
    Floral scale shape
    • the floral scales are oblong (rectangular but with rounded ends)
    • the floral scales are obovate (roughly egg-shaped, but with the widest part above the middle)
    Floral scale translucent
    the floral scales are opaque
    Flower number per cluster
    more than 20
    Inflorescence bract angle
    the bracts are vertical or angled only slightly outwards
    Inflorescence bract number
    there are two to five bracts per inflorescence
    Inflorescence bract position (Sparganium)
    NA
    Inflorescence bracts
    there are at least two bracts, and they are either flat or folded or rolled in at the edges
    Inflorescence branching
    • the inflorescence is branched
    • the inflorescence is on one or more stems with no branches
    Inflorescence crowding
    the inflorescence is crowded together in one tight cluster
    Inflorescence position
    • the inflorescence emerges from an axil, or most of its parts do so
    • the inflorescence is at the tip of the plant
    Inflorescence shape
    the aggregations within the inflorescence are roughly circular (not flattened) in cross-section
    Inflorescence type
    • there are two or more flowers, spikes or flower clusters on a branched inflorescence
    • there is one spike or raceme at the tip of the stem
    Perianth composition
    there are three bristles and three scales on narrow stalks, attached at the base of the achene
    Stamen number
    • 1
    • 2
    • 3
    Stigma number
    3
    Style division
    the top two thirds of the style is divided
    floral bristle barbs
    the bristles have tiny barbs on them
    plantlets budding at flower bases
    no

  • Fruits or seeds

    Achene surface texture
    the achene is smooth (it has no detectable texture)
    Achene tubercle relative width
    NA
    Achene tubercle width
    0 mm
    Capsule relative length
    NA
    Fruit cross-section
    the fruit is triangular to terete (circular) in cross-section
    Fruit length
    0.6–1 mm
    Fruit type (general)
    the fruit is like a seed, and surrounded by scales
    Fruit type (specific)
    the fruit is an achene (dry, seed-like fruit) without a tubercle (a swelling or projection, usually of a different color or texture)
    Locules in capsule
    NA
    Seed length
    0 mm
    Seed tail relative length
    0 mm
    Seed tails
    NA
    Tubercle height
    0 mm

  • Growth form

    Lifespan
    the plant lives only a single year or less
    Underground organs
    there are only slender roots on the plant

  • Leaves

    Leaf blade cross-section
    the leaf blade is flat or rolled in at the edges
    Leaf blade length
    50–120 mm
    Leaf blade width
    3–5 mm
    Leaf form
    all the leaves hold their form out of water
    Leaf position on plant
    some leaf attachment points are above the midpoint of the stem
    Leaf septa
    the leaf blades do not have transverse septa
    Leaf sheath hairs
    the leaf sheathes have hairs on them
    Pedicel length (Typha)
    0 mm
    Stem leaf blade ligules
    the plant has ligules at the leaf blade bases
    Stem leaf blades
    there are fully-developed leaves with leaf blades on the main stem

  • Place

    Habitat
    • aquatic
    • wetlands
    New England state
    • Connecticut
    • Massachusetts
    • Rhode Island
    Specific habitat
    • in lakes or ponds
    • shores of rivers or lakes

  • Stem, shoot, branch

    Plant height
    8–60 cm
    Stem shape in cross-section
    the stem is roughly triangular in cross-section
    Stem texture near tip
    the stem feels smooth near the tip

Wetland status

Occurs only in wetlands. (Wetland indicator code: OBL)

In New England

Distribution

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

Conservation status

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

Connecticut
unrankable (S-rank: SU)
Massachusetts
uncommon (S-rank: S3)
Rhode Island
extremely rare (S-rank: S1), state endangered (code: SE)

From Flora Novae Angliae dichotomous key

1.  Fuirena pumila (Torr.) Spreng. N

dwarf umbrella-sedge. Fuirena squarrosa Michx. var.  pumila Torr. • CT, MA, RI. Sandy or peaty pond shores and low areas on the coastal plain.

Native to North America?

Yes

Sometimes confused with

Fuirena squarrosa:
plants perennial from short rhizomes and corm-like offshoots and flowers with 3 stamens that have anthers 0.7-1 mm long (vs. F. pumila, the plants annual from fibrous roots and flowers with 1-3 stamens that have anthers 0.5-0.7 mm long).

Synonyms

  • Fuirena squarrosa Michx. var. pumila Torr.

Family

Cyperaceae

Genus

Fuirena