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- Dichotomous Key
- Poaceae
- Poaceae Group 5
- Taeniatherum
- Taeniatherum caput-medusae
Taeniatherum caput-medusae — Medusa-head
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Facts
Medusa-head is a non-native grass that is considered a noxious weed in several western states, where it has invaded vast areas formerly dominated by native perennial grasses. In New England it is a rare visitor, having been collected only in Connecticut.
Habitat
Anthropogenic (man-made or disturbed habitats)
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.
Found this plant? Take a photo and post a sighting.
Characteristics
- Habitat
- terrestrial
- New England state
- Connecticut
- Leaf blade width
- 0.2–2.5 mm
- Inflorescence branches
- there are no branch points between the base of the inflorescence axis and the flowers, or they are not obvious
- Spikelet length
- 6–12 mm
- Glume relative length
- neither glume is quite as long as all of the florets
- Awn on glume
- the glume has an awn
- One or more florets
- there is more than one floret per spikelet
- Lemma awn length
- 20–110 mm
- Leaf sheath hair type
-
- there are hairs on the surface of the leaf sheath, but the hairs do not have blisters at their bases
- there are no hairs on the surface of the leaf sheath
- Leaf ligule length
- 0.2–0.6 mm
- Anther length
- 0–1 mm
-
Flowers
- Anther length
- 0–1 mm
- Anther number
- 0–3
- Awn on glume
- the glume has an awn
- Bristles below spikelets
- no
- Floret lower bract texture
- the lemma is thin and flexible
- Floret number
- 2–3
- Floret types within spikelet
- there are at least two distinct forms of florets within one spikelet
- Glume awn length
- 5–80 mm
- Glume relative length
- neither glume is quite as long as all of the florets
- Glume veins
-
- 1
- 3
- Glumes per spikelet
- 2
- Inflorescence axis hairs
- the inflorescence axis is smooth and has no hairs
- Inflorescence axis orientation
- the inflorescence axis is straight
- Inflorescence branch length
- 0 cm
- Inflorescence branch roughness
- NA
- Inflorescence branches
- there are no branch points between the base of the inflorescence axis and the flowers, or they are not obvious
- Inflorescence branches coming off the lowest stem node
- 0
- Inflorescence crowding
- NA
- Inflorescence length
- 12–60 mm
- Inflorescence type (general)
- the inflorescence is a spike, or is spike-like, lacking obvious branches
- Inflorescence type (specific)
- the inflorescence is a spike (a long unbranched stem with flowers along it that lack stalks)
- Inforescence position
- the spikelets are mainly carried at the end of the stem
- Lemma awn base
- the awn is attached right at the tip of the lemma
- Lemma awn coiled
- the lemma awn is straight or twisted, but not coiled one half turn
- Lemma awn length
- 20–110 mm
- Lemma awn number
- the lemma has one awn on it
- Lemma awn orientation
-
- the awn of the lemma is straight
- the awn of the lemma on dried or older plants is curved or bent outwards
- Lemma cross-section
- the lemma is flat or rounded if you cut across the midpoint
- Lemma hairs
- the lemma is hairless between the veins
- Lemma keel hairs
- NA
- Lemma marginal vein hairs
- the marginal vein of the lemma is hairless
- Lemma surface
- 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 long narrow point (it may or may not also have an awn or teeth at the tip)
- Lemma vein number
- 5
- Lemma vein orientation
- the veins on the lemma stay roughly parallel throughout
- 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
- At least 0 mm
- Palea relative length
- palea is less than one half as long as lemma or absent
- Reproductive system
- all the flowers on the plant have both carpels and stamens (synoecious)
- Spikelet axis tip
- there is no 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
- 6–12 mm
- Spikelet number per node
- Up to 4
- Spikelet pedicel
- the spikelets do not have pedicels
- Spikelet pedicel length
- 0 mm
- Spikelet position
- NA
- Spikelet shape
- the spikelets are another shape in profile
- Spikelets per panicle branch
- 0
- 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 up to one half as long as the lowest lemma
- Upper glume shape
- the upper glume is widest at or below the middle
-
Fruits or seeds
- Groove on seed
- the caryopsis has a groove running most of its length
- Seed length
- 4–5.2 mm
-
Growth form
- Horizontal rooting stem
- no
- Lifespan
- the plant lives only a single year or less
- Rhizomes
- no
- Roots
- there are only slender roots on the plant
-
Leaves
- Leaf auricles
-
- the leaves do not have auricles
- the leaves have auricles
- Leaf basal lobe hairy
- the lobes at the base of the leaf blades are hairless
- Leaf blade cross-section
-
- the leaf blade is clearly folded or rolled inwards
- the leaf blade is more or less flat in cross-section, or slightly folded or rolled inwards
- Leaf blade hairs
- the leaf blade is hairy
- Leaf blade length
- 3–12 cm
- Leaf blade texture
-
- the leaf blade is rough and sandpapery
- the leaf blade is smooth, or it may have soft hairs
- Leaf blade width
- 0.2–2.5 mm
- Leaf ligule length
- 0.2–0.6 mm
- Leaf ligule type
- the leaf ligule is in the form of a membrane
- 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 hair type
-
- there are hairs on the surface of the leaf sheath, but the hairs do not have blisters at their bases
- there are no hairs on the surface of the leaf sheath
- Leaf sheath hairs
-
- there are hairs on the surface of the leaf sheath
- there are no hairs on the surface of the leaf sheath
- Orientation of topmost leaf
-
- the flag leaf is held outward at more than a 45 degree angle from the stem, or it curves downwards from the horizontal
- the flag leaf is held upright, or at less than a 45 degree angle out from the stem
-
Place
- Habitat
- terrestrial
- New England state
- Connecticut
- Specific habitat
- man-made or disturbed habitats
-
Stem, shoot, branch
- Plant height
- 5–70 cm
- Stem hairs
- the stem is nearly to completely hairless
- Stem node number
- 3–6
- Stem orientation
-
- the stems are upright
- the stems trail at the base, but turn upwards at the tips
- Stem spacing
-
- the stems grow close together in compact clusters or tufts
- the stems grow singly or a few together (they may form diffuse colonies)
Wetland status
Not classified
In New England
Distribution
- Connecticut
- present
- Maine
- absent
- Massachusetts
- absent
- New Hampshire
- absent
- Rhode Island
- absent
- Vermont
- absent
Conservation status
None
Subspecies and varieties
Our subspecies is Taeniatherum caput-medusae (L.) Nevski ssp. caput-medusae.
From Flora Novae Angliae dichotomous key
1. Taeniatherum caput-medusae (L.) Nevski ssp. caput-medusae E
Medusa-head. Elymus caput-medusae L. • CT. Disturbed soil, waste places.
Native to North America?
No
Sometimes confused with
- Secale cereale:
- spikelets solitary at each node, lemma awns 7-50 mm long, and anthers ca. 7 mm long (vs. T. caput-medusae, with spikelets usually paired at each node, lemma awns mostly 30-110 mm long, and anthers 0.8-1 mm long).
Synonyms
- Elymus caput-medusae L.