Grasses, Sedges and Rushes

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What's the difference?

Grasses: the Poaceae family

illustration of some grass characteristics

  • Stems jointed, hollow, usually round in cross-section, branched or not
  • Sheaths usually open in the front, though edges often overlap
  • Leaves 2-ranked (on opposite sides of the stem)
  • Flowers usually perfect (both male and female parts)
  • Each floret wrapped in 2 bracts/scales
  • One seed (grain) per flower

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Rushes: the Juncaceae family

illustration of some rush characteristics

  • Stems round or compressed in cross-section, not jointed or hollow, branched or not
  • Leaves few, mostly basal, round or flat in cross-section
  • Sheaths open in front, often auricled
  • Flowers perfect, 3 or 6 stamens, 6 tepals
  • Capsules with 3 or many seeds

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Sedges: the Cyperaceae family

illustration of some general sedge characteristics

  • Stems round or 3-sided in cross-section, not hollow or jointed, not usually branched
  • Sheaths usually closed in the front
  • Leaves usually 3-ranked (in 3 columns when viewed from the side of the stem)
  • Flowers male or female or perfect, each subtended by a single scale/bract
  • One seed (achene) per flower
  • Achenes lens-shaped or 3-sided, may have bristles or hairs around the base

Subsections follow, or Browse all sedges

Sedges: Carex species

illustration of some Carex characteristics

  • Stems usually 3-sided, leaves 3-ranked
  • Flowers either male or female; spikelets all-male, all-female or mixed
  • Florets/achenes enclosed in a sac (perigynium), open only at the tip
  • Each perigynium subtended by a single scale; usually spirally arranged
  • Achenes lack bristles

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Flatsedges, Nutsedges, Umbrella sedges: Cyperus species

illustration of some flatsedge characteristics

  • Terminal clusters of multiple spikelets; clusters often round or bottle-brush shaped
  • Spikelets usually flattened
  • Perfect flowers, 2-ranked (florets on opposite sides of the spikelet stalk)
  • Each floret/achene surrounded by a single scale
  • Achenes lack bristles

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Bulrushes: Scirpus, Schoenoplectus, Bulboschoenus species

illustration of variations in Bulrush inflorescence arrangement

  • Stems round or 3-sided in cross-section, spongy or firm
  • Stem leaves sometimes bladeless or nearly so
  • Clusters of few to many, lance-elliptic spikelets, variously arranged
  • Leaf-like bracts, or bract appearing as a continuation of the stem
  • Perfect flowers, spirally arranged on the spikelet
  • Achenes usually with bristles

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Spikerushes: Eleocharis species

illustration of some Eleocharis characteristics

  • Stems round or compressed in cross-section, usually spongy
  • Leaves all basal, 2 per stem; lower stem is sheathed
  • Single spike at stem tip, usually oval-elliptic; scale-like bracts
  • Perfect flowers, spirally arranged on the spike
  • Achenes with conspicuous ­“cap” at tip, usually have bristles

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Cottongrasses: Eriophorum species

illustration of Cottongrass examples

  • Stems round or 3-sided in cross-section
  • Stem leaves sometimes bladeless or nearly so
  • Terminal cluster of several to many, lance-elliptic spikelets, variously arranged
  • Perfect flowers, spirally arranged on the spikelet
  • Achenes with long, smooth, white or tawny colored hairs

Profiles coming soon.

Other sedges

illustration of some sedge characteristics

  • Not as above, or other combinations of traits
  • Achenes may have bristles
  • Includes: Bulbostylis, Cladium, Dulichium, Fimbristylis, Lipocarpha, Rhynchospora, Scleria, Trichophourm species

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