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- Dichotomous Key
- Poaceae
- Poaceae Group 4
- Poa
- Poa interior
Poa interior — interior blue grass
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New England distribution
Adapted from BONAP data
Native: indigenous.
Non-native: introduced (intentionally or unintentionally); has become naturalized.
County documented: documented to exist in the county by evidence (herbarium specimen, photograph). Also covers those considered historical (not seen in 20 years).
State documented: documented to exist in the state, but not documented to a county within the state. Also covers those considered historical (not seen in 20 years).
Note: when native and non-native populations both exist in a county, only native status is shown on the map.
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Facts
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.
Habitat
Alpine or subalpine zones, cliffs, balds, or ledges, talus and rocky slopes, woodlands
Characteristics
- Habitat
- terrestrial
- 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
-
Flowers
- Anther length
- 1.1–2.5 mm
- Anther number
- 3
- Awn on glume
- the glume has no awn
- Bristles below spikelets
- no
- Floret lower bract texture
- the lemma is thin and flexible
- Floret number
- 1–5
- 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
- 3
- Glumes per spikelet
- 2
- 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
- 2–5
- 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
- 2.5–4
- 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
- NA
- Lemma awn coiled
- NA
- Lemma awn length
- 0 mm
- Lemma awn number
- the lemma has no awn
- Lemma awn orientation
- NA
- 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
- no
- Lifespan
- the plant lives more than two years
- Rhizomes
- no
- Roots
- there are only slender roots on the plant
-
Leaves
- Leaf auricles
- the leaves do not have auricles
- Leaf basal lobe hairy
- NA
- 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
- Habitat
- terrestrial
- 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
- no
- 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)
New England distribution and conservation status
Distribution
- Connecticut
- absent
- Maine
- absent
- Massachusetts
- absent
- New Hampshire
- absent
- Rhode Island
- absent
- Vermont
- present
Conservation status
Exact status definitions can vary from state to state. For details, please check with your state.
- Vermont
- extremely rare (S-rank: S1)
Native to North America?
Yes
Sometimes confused with
- Poa glauca:
- lemmas usually at least sparsely pubescent on the lateral veins, uppermost stem node usually positioned at 1/10 to 1/3 stem height, and ligules mostly 1.2–2 mm long (vs. P. interior, with lemmas glabrous on the lateral veins uppermost stem node usually positioned at 1/3 to 3/5 stem height, and ligules 0.5–1.5 mm long).
Synonyms
- Poa nemoralis L. ssp. interior (Rydb.) W.A. Weber
- Poa nemoralis L. var. interior (Rydb.) Butters & Abbe
Family
Genus
From the dichotomous key of Flora Novae Angliae
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.