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Poa interior — interior blue grass

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Interior blue grass enters New England only in northern Vermont. This is a rare grass from talus slopes, cliffs and gullies, and rocky woodlands where the rock is high-pH.


Alpine or subalpine zones, cliffs, balds, or ledges, talus and rocky slopes, woodlands

New England distribution

Adapted from BONAP data

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North America distribution

Adapted from BONAP data



Leaf blade width
0.8–3 mm
Inflorescence branches
the flowers are attached to branches rather than to the main axis of the inflorescence
Spikelet length
3–6 mm
Glume relative length
neither glume is quite as long as all of the florets
Awn on glume
the glume has no awn
One or more florets
there is more than one floret per spikelet
Lemma awn length
0 mm
Leaf ligule length
0.5–1.5 mm
Anther length
1.1–2.5 mm
Show all characteristics
  • Flowers

    Anther length
    1.1–2.5 mm
    Anther number
    Awn on glume
    the glume has no awn
    Bristles below spikelets
    Floret lower bract texture
    the lemma is thin and flexible
    Floret number
    Floret types within spikelet
    all the florets within a spikelet are similar
    Glume awn length
    0 mm
    Glume keel
    • the glume keels are rough or hairy
    • the glume keels are smooth and hairless
    Glume relative length
    neither glume is quite as long as all of the florets
    Glume shape
    the glume is V-shaped in cross-section
    Glume veins
    Glumes per spikelet
    Inflorescence arrangement
    the spikelets are uniform
    Inflorescence axis orientation
    • the inflorescence axis bends downwards or hangs
    • the inflorescence axis is arched or curved outward
    • the inflorescence axis is straight
    Inflorescence branch length
    0.4–9 cm
    Inflorescence branch roughness
    the inflorescence branches are somewhat to very rough
    Inflorescence branches
    the flowers are attached to branches rather than to the main axis of the inflorescence
    Inflorescence branches coming off the lowest stem node
    Inflorescence crowding
    • the panicle is somewhat to very congested (crowded), and the branches may not be clearly seen without close inspection
    • the panicle is somewhat to very spread out, with clearly-evident branches
    Inflorescence length
    15–170 mm
    Inflorescence length to width ratio
    Inflorescence type (general)
    the spikelets are borne on stalks or on branches
    Inflorescence type (specific)
    the inflorescence is branched, and the branches do NOT both grow from the same side of the plant AND look like spikes
    Inforescence position
    the spikelets are mainly carried at the end of the stem
    Lemma awn base
    Lemma awn coiled
    Lemma awn length
    0 mm
    Lemma awn number
    the lemma has no awn
    Lemma awn orientation
    Lemma base hairs
    • the lemma has hairs at the base
    • the lemma is hairless or feels just a tiny bit rough at the base
    Lemma cross-section
    the lemma is V-shaped if you cut across the midpoint
    Lemma hairs
    the lemma is hairless between the veins
    Lemma keel hairs
    the keel of the lemma is rough, or has fine hairs
    Lemma marginal vein hairs
    the marginal vein of the lemma has fine hairs on it
    Lemma surface
    • the surface of the lemma is covered with small wart-like projections
    • the surface of the lemma is relatively smooth (not counting any longitudinal veins or hairs)
    Lemma tip
    the lemma tip is a simple point, with or without an awn (long narrow extension ending in a point)
    Lemma tip shape
    the lemma tip tapers to a narrow point (it may or may not also have an awn or teeth at the tip)
    Lemma vein number
    • 3
    • 5
    Lower glume relative length
    the lower glume is nearly as long, or as long as, the upper glume
    One or more florets
    there is more than one floret per spikelet
    Palea length
    2.4–4 mm
    Palea relative length
    palea is one half to fully as long as lemma
    Reproductive system
    all the flowers on the plant have both carpels and stamens (synoecious)
    Spikelet axis tip
    there is an extension of the spikelet axis beyond the tip of the spikelet
    Spikelet disintegration
    the spikelet breaks off above the glumes, so that after the florets fall off, the glumes remain
    Spikelet length
    3–6 mm
    Spikelet number per node
    Up to 0
    Spikelet pedicel
    the spikelets have pedicels
    Spikelet shape
    • the spikelets are lanceolate (lance-shaped, widest below the middle and tapering narrowly to the ends) in profile
    • the spikelets are ovate (egg-shaped, widest below the middle with rounded ends) in profile
    Spikelet width
    1.2–2.6 mm
    Spikelets spiny
    the spikelets do not appear spiny
    Tip of glume
    the tip of the glume is not divided (though it may have an awn on it)
    Upper glume relative length
    the upper glume is more than one half as long as the lowest lemma
    Upper glume shape
    the upper glume is widest at or below the middle
  • Growth form

    Horizontal rooting stem
    the plant lives more than two years
    there are only slender roots on the plant
  • Leaves

    Leaf auricles
    the leaves do not have auricles
    Leaf basal lobe hairy
    Leaf blade base
    the leaf blade is rounded in to a narrower base, or the blade cuts in abruptly to the narrower base
    Leaf blade cross-section
    the leaf blade is more or less flat in cross-section, or slightly folded or rolled inwards
    Leaf blade hairs
    the leaf blade is hairless, but it may have tiny prickles that give it a sand-papery feel
    Leaf blade length
    6–15 cm
    Leaf blade texture
    the leaf blade is smooth, or it may have soft hairs
    Leaf blade width
    0.8–3 mm
    Leaf ligule length
    0.5–1.5 mm
    Leaf ligule type
    the leaf ligule is in the form of a membrane with fine hairs
    Leaf margin glands
    there are no glands along the edges of the leaf blade
    Leaf sheath closed around stem
    the margins of the leaf sheath are overlapping and not fused together except in the basal half (or less)
    Leaf sheath color and persistence
    the leaf sheathes are off-white to light-brown and mostly persist in older leaves
    Orientation of topmost leaf
    the flag leaf is held upright, or at less than a 45 degree angle out from the stem
  • Place

    Specific habitat
    • alpine or subalpine zones
    • cliffs, balds, or ledges
    • talus or rocky slopes
    • woodlands
  • Stem, shoot, branch

    Hairs at nodes
    the stem nodes are hairless or they have very sparse hairs
    Plant height
    5–80 cm
    Roots at lower stem nodes
    Stem hairs
    the stem is nearly to completely hairless
    Stem orientation
    the stems are upright
    Stem spacing
    the stems grow close together in compact clusters or tufts

Wetland status

Occurs in wetlands or non-wetlands. (Wetland indicator code: FAC)

In New England


New Hampshire
Rhode Island

Conservation status

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

extremely rare (S-rank: S1)

From Flora Novae Angliae dichotomous key

7.  Poa interior Rydb. NC

interior blue grass. Poa nemoralis L. ssp. interior (Rydb.) W.A. Weber; P. nemoralis L. var. interior (Rydb.) Butters & Abbe • VT; northern portion of state. Talus, cliffs, rocky woodlands, limestone headlands, subalpine gullies. Most collections determined as Poa glauca or 
as P. nemoralis from pristine locations on high-pH substrate in VT were in fact P. interior. Therefore, P. glauca is rarer than previously believed.

Native to North America?


Sometimes confused with

Poa glauca