Graminoids and the big three grasses, Rushes and Sedges

Дата канвертавання22.04.2016
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Grasses, Rushes and Sedges
Grasses are featured most in Marshes.

Rushes are most common in shoreline ecosystems.

Sedges are the key graminoid of peatlands.

Linear it a Grass, a Rush or a Sedge?

KEY to the BIG THREE: Grass Sedge or Rush
1. Leaves tubular or wiry, rarely grass-like (Juncus marginatus)

Flowers miniature lilies with parts (petals and sepals) in threes

RUSHES = Juncus species
1. Leaves usually grass-like but maybe inrolled in certain sedges

Flower parts are bracts or bristles, flower parts not in threes

2. Leaf sheaths open, stems round in cross-section and hollow, leaves often two-ranked
2. Leaf sheaths closed, stems triangular, leaves 3-ranked—usually


The true rushes are part of the Juncaceae Family and we deal here with only the genus Juncus for the wood rush genus (Luzula) is not a wetland genus. Juncus species are most common on lake shorelines although there are weedy Juncus in ditches and farm fields as well as Juncus species in saltmarshes and in peatlands.


Lake shores typically house four Juncus species and a lakeshore key follows:
1. Plants tall 40 to 100cm tall

2. Plant usually in deep water with one leaf projecting from then mid point of flowering stem and surpassing flowers. Plants form a distinctive red/green zone in late summer. Seeds without white tails.... Military Rush (Juncus militaris)

2. Plants scattered over shoreline with leaves not surpassing inflorescence. Seeds with tails..... Canada Rush (Juncus canadensis)
1. Small plants to 50cm tall
3. Stems in a line coming from a linear underground rhizome. Flowers in clusters of 5-7 ?? produced from the side of stems below the tip
Thread Rush (Juncus filiformis)

3. Stems branching extensively and widely. Flowers in groups of 2-3?? at tips of branches

Brown-Fruited Rush (Juncus pelocarpus)

PHOTO of LAKE SHORE....of Juncus militaris zone, of Juncus filiformis linear rhizomes...of J. pelocarpus with bulbils

Photo of damp field with Soft Rush ...of ditch with Jointed Rush
1. Tall Plants (maybe more than a metre tall) of dense clumps of soft, dark green "leaves" (flower stems) with flower clusters borne on the sides of stems just below their tips.
Soft Rush (Juncus effusus)

1. Small plants, mostly less than 50cm tall

2. Tiny annual plants tiny (e.g. 10-15 cm tall), flowers borne over half of the height of plant

Toad Rush (Juncus bufonius)

2. Perennial plants, 20-50 cm tall, flowers usually borne in the top third of plant

3. Leaves tubular, not flat or merely inrolled

4. Plant stems erect, leaves per stem usually 1-2, seeds with tails

Narrow-Panicled Rush (Juncus

4. Plant stems erect, curved to decumbent and rooting at base, leaves per stem 3-6. seeds without tails

Jointed Rush (Juncus articulatus)

3. Leaves flat or narrow and inrolled (caution: may appear tubular)
5. Leaves flat (yellow-listed)

Marginal Rush (Juncus marginatus)

5. Leaves narrow and inrolled
6* top of leaf sheath at base of leaf blade prolonged as a whitish, delicate membrane, an auricle (1-5mm long)

Slender Rush (Juncus tenuis)

6* auricle scant or up to 0.5mm long, may be yellowish and hard

Dudley's Rush (Juncus dudleyi)

* Degree of difficulty step to differentiate common Juncus tenuis from rare Juncus dudleyi. Distinction made on auricle alone leading Hines (2000) to comment that Dudley's Rush is a bit of a far as auricles go.


Rushes are not well represented in peatlands but there are 4 rushes you should look out for which with the exception of Caesar's Rush from Cape Breton, are also found in the previous habitats (e.g. lakes and ditches).
PHOTO of Bog Pool with J canadensis

of marginal zone with rare J caesariensis, of J subcaudatus in spruce swamp

1. Plants small (10-30cm), slender, widely branching. Flowers usually borne as singly

Brown-Fruited Rush (Juncus pelocarpus)
1. Plants mid-size (to 70 cm) to large (to 1m). Flowers in heads of 2-many
2. Leaves rough to touch, seeds at least 2 mm long (Red listed, known Canadian range is eastern Cape Breton)

Caesar's Rush (Juncus caeariensis)

2. Leaves smooth to touch, seeds less than 2 mm long

3. Capsule not projecting much past the six tepals, white tails of seeds

almost as long as body of seed

Canada Rush (Juncus canadensis)

Canada Rush in stream from fen (Left) and in a fen pool (Right)

3. Capsule projects noticeably past the six tepals, tails of seeds only 1/3

length of the seed itself

Woodland Rush (Juncus subcaudatus)


Saltmarsh plants occur in zones mainly set by the amount of daily immersion in salt water they receive. There are two ubiquitous saltmarsh rushes and one other which has a broad salt tolerance, occurring in freshwater and saltwater shores.

1. Inflorescence (flowers) borne from sides of stems, stems borne from linear running rhizome—usually upper saltmarsh

Baltic Rush (Juncus balticus)
1. Inflorescence terminal
2. Spherical heads of flowers, mainly northeastern counties, wide habitat range
Knotted Rush (Juncus nodosus)
2. Flowers not grouped in compact heads, borne individually. Occurs in large patches in or adjacent to salthay (Spartina patens) zone in saltmarsh
Black Grass (Juncus gerardii)

PHOTOS...Upper saltmarsh Baltic Rush

Black grass patch in saltmarsh

Black Grass (Juncus gerardii) patch in salthay zone at Grand Pre

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