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• Fuirena pumila

Fuirena pumila — dwarf umbrella-sedge

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

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)

New England distribution and conservation status

From the dichotomous key of Flora Novae Angliae