Swamp Grasses

Rice Cut-grass Blunt Manna-grass Annual Wild-rice Floating Manna-grass

What are they?

Lumped together here are a small number of grasses which, though not all directly related to each other, nevertheless occur in similar habitats and have superficially similar, rather open flower heads.

Where are they found?

These are plants of permanently or near-permanently wet ground, in marshes, swamps and along permanent water courses.

Identification

Identification is covered under the individual species.



Rice Cut-grass      Leersia oryzoides

A fairly common and widespread, broad-leaved species of wet areas, often in woodland and other shady places. Flowers June to September. Often forms lush, open stands beside boggy ruts and hollows. Flowers have distinctive, bristly hairs along the margins.
Rice Cut-grass Rice Cut-grass Rice Cut-grass Rice Cut-grass
Habit
Flower cluster at
top of spike
Flower Close-up
Leaf ligule

Annual Wild-rice      Zizania aquatica

(Wild Rice) Not the rice of cultivation but closely related to it and once used as a substitute rice. Common and quite widespread in open swamps along main waterways, especially close to the tidal limit. Flowers July to September. Can form extensive stands; a tall grass which often stands head and shoulders above surrounding vegetation. Has a very distinctive flower spike, with the female flowers borne in a narrow tuft at the top and the male flowers on spreading branchlets lower down.
Annual Wild-rice Annual Wild-rice Annual Wild-rice Annual Wild-rice
Habit
Flower spike
Lower branch of
flower spike
Leaf ligule

Blunt Manna-grass      Glyceria obtusa

(Atlantic Manna-grass) Wet fields and swamps. Flowers July to September. Flower spikes more compact than other manna-grasses.
Blunt Manna-grass Blunt Manna-grass Blunt Manna-grass Blunt Manna-grass
Flower spike
Flower spikelet
Leaf ligule
Seedheads

Nerved Manna-grass      Glyceria striata

(Fowl Manna-grass) Wet fields and swamps, usually in open areas but occasionally also in woodland. Flowers May to June. A small, rather open grass compared to other swamp grasses and best told from other manna-grasses by the raised veins on the flowers. The stem is slightly flattened, giving a rounded edge on two sides.
Nerved Manna-grass Nerved Manna-grass Nerved Manna-grass Nerved Manna-grass
Flower spike
Young flower spikelets
Mature flower spikelets
Leaf ligule

Floating Manna-grass      Glyceria septentrionalis

Local in wet, swampy ground and often growing semi-aquatically in shallow water. Flowers May to July. Both the flower spike and the spikelets are long and slender; the flower spike often has one or two rather long side branches at the base.
Floating Manna-grass Floating Manna-grass Floating Manna-grass Floating Manna-grass
Flower spike
Flower spikelets
Flower spikelets
Ligule

Pale False Manna-grass      Torreyochloa pallida

Local in wet, swampy ground and often growing semi-aquatically in shallow water. Flowers May to June.
Pale False Manna-grass Pale False Manna-grass Pale False Manna-grass Pale False Manna-grass
Flower spike
Flower spikelets
Spikelets close-up
Ligule

Northern Sweet-grass      Anthoxanthum hirtum

Wet fields and swamps, especially at the freshwater margins of coastal marshes. Flowers April to June. Usually found growing in open colonies of feathery, golden-toned flowerheads.
Northern Sweet-grass Northern Sweet-grass Northern Sweet-grass Northern Sweet-grass
Habit
Flower spike
Flower spikelet
Stem leaf

Wood Reed-grass      Cinna arundinacea

A tall and graceful species of wet woodland. Flowers August to September. One distinctive feature of this species can be found in the leaves, which are twisted by 90 degrees at the base.
Wood Reed-grass Wood Reed-grass Wood Reed-grass
Flower spike
Flower spikelets
Leaf ligule

Nuttall's Reed-grass      Calamagrostis coarctata

Wet fields and swamps, usually in open areas. Flowers June to September. The rather narrow, upright flowerhead is crammed with many, very small, awnless flower spikelets. Listed in most flower books under an older scientific name of Calamagrostis cinnoides.
Nuttall's Reed-grass Nuttall's Reed-grass Nuttall's Reed-grass Nuttall's Reed-grass
Flower spike
Flower spike
Flower spikelets
Leaf ligule

Blue-joint Reed-grass      Calamagrostis canadensis

Not uncommon in marshes and other open, swampy areas. Flowers June to July. Forms spreading patches of blue-green vegetation which are quite distinctive.
Blue-joint Reed-grass Blue-joint Reed-grass Blue-joint Reed-grass Blue-joint Reed-grass
Habit
Flower spike
Flower spikelets
Leaf ligule

Swamp Wedgescale      Sphenopholis pensylvanica

An uncommon species of wetlands, especially swamp woodland. Flowers May to June. The flower spike is narrow and gracefully arching, each flower with a single, long awn.
Swamp Wedgescale Swamp Wedgescale Swamp Wedgescale
Flower spike
Flower close-up
Flower close-up

Blue Maidencane      Amphicarpum amphicarpon

(Pine Barrens Peanut Grass) A rare grass of wetlands and damp, sandy soil. Flowers September to October. An unusual grass which can grow to some six feet tall (though is often much shorter and can be told by the obvious, bristly hairs on the leaves and stem. As well as regular flowers, that form a narrow, finger-like spike, this species also produces peculiar, self-fertilizing flowers below ground.
Blue Maidencane Blue Maidencane Blue Maidencane Blue Maidencane
Flower spike
Flowers close-up
Subterranean flower
Leaf and stem bristly

Bearded Sprangletop      Diplachne fascicularis

An uncommon grass of wetlands which is most often found at coastal sites where the water is at least a little brackish. Flowers August to September.
Bearded Sprangletop Bearded Sprangletop Bearded Sprangletop Bearded Sprangletop
Flower spike
Florets close-up
Leaf has basal silver streak
Leaf ligule

New Jersey Hair-grass      Muhlenbergia torreyana

A widespread but local grass, favoring seasonally wet hollows where it can often form large, dense stands of vegetation. Flowers September to October. Probably most easily identified by its strongly flattened stems and leaves which are folded in two for most of their length.
New Jersey Hair-grass New Jersey Hair-grass New Jersey Hair-grass New Jersey Hair-grass
Habit
Flowering spike
Florets close-up
Leaf ligules

Bog Hair-grass      Muhlenbergia uniflora

A pine barren species that occurs in a few boggy locations in the north of the county. Flowers August to October. A small, delicate species that is easily overlooked among large stands of bog sedges and grasses.
Bog Hair-grass Bog Hair-grass Bog Hair-grass
Flowering spike
Florets close-up
Leaf ligule

Wrinkled Joint-grass      Coelorachis rugosa

A south-eastern grass of wet meadows and marshes which still can be found at its only New Jersey site at Cold Spring. Flowers August to October. An extremely rare grass locally but should be looked for elsewhere in suitable habitat. The whole plant often turns reddish as the fruits develop, making it more obvious later in the year.
Wrinkled Joint-grass Wrinkled Joint-grass Wrinkled Joint-grass Wrinkled Joint-grass
Habit
Florets close-up
Seed head
Leaf ligule