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- True grasses
- Digitaria ischaemum
Digitaria ischaemum — smooth crabgrass
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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
Smooth crabgrass is native to Eurasia and introduced in North America. It is a common weed of lawns but slighly less aggressive than hairy crabgrass (Digitaria sanguinalis).
Habitat
Anthropogenic (man-made or disturbed habitats)
Characteristics
- Habitat
- terrestrial
- New England state
-
- Connecticut
- Maine
- Massachusetts
- New Hampshire
- Rhode Island
- Vermont
- Leaf blade width
- 3–5 mm
- Inflorescence branches
- the flowers are attached to branches rather than to the main axis of the inflorescence
- Spikelet length
- 1.7–2.3 mm
- Glume relative length
-
- neither glume is quite as long as all of the florets
- one or both glumes are as long or longer than all of the florets
- Awn on glume
- the glume has no awn
- One or more florets
-
- there is more than one floret per spikelet
- there is one floret per spikelet
- Lemma awn length
- 0 mm
- Leaf ligule length
- 0.6–2.5 mm
- Anther length
- 0.4–0.6 mm
-
Flowers
- Anther length
- 0.4–0.6 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
- 1–2
- Floret types within spikelet
-
- NA
- there are at least two distinct forms of florets within one spikelet
- Glume awn length
- 0 mm
- Glume keel
- the glume keels are rough or hairy
- Glume relative length
-
- neither glume is quite as long as all of the florets
- one or both glumes are as long or longer than all of the florets
- Glume shape
- the glume is flat or curved in cross-section
- Glume veins
-
- 0
- 1
- 3
- 5
- 7 or more
- Glumes per spikelet
-
- 1
- 2
- Inflorescence arrangement
- the spikelets are uniform
- Inflorescence axis orientation
- the inflorescence axis is straight
- Inflorescence branch length
- 6–15.5 cm
- Inflorescence branches
- the flowers are attached to branches rather than to the main axis of the inflorescence
- Inflorescence crowding
- the panicle is somewhat to very spread out, with clearly-evident branches
- Inflorescence type (general)
- the spikelets are borne on stalks or on branches
- Inflorescence type (specific)
- the inflorescence is branched and the branches all 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
- the spikelets are mainly found at the nodes, in the axils of leaves, along 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 cross-section
- the lemma is flat or rounded if you cut across the midpoint
- Lemma hairs
- the lemma has fine hairs between the veins
- Lemma keel hairs
- the keel of the lemma is rough, or has fine hairs
- 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 vein number
-
- 1
- 3
- 5
- 7 or more
- Lower glume length
- At least 0 mm
- Lower glume relative length
- the lower glume is one third or less as long as the upper glume
- One or more florets
-
- there is more than one floret per spikelet
- there is one floret per spikelet
- Palea length
- 1.8–2.2 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 no extension of the spikelet axis beyond the tip of the spikelet
- Spikelet disintegration
- the spikelet breaks off below the glumes
- Spikelet length
- 1.7–2.3 mm
- Spikelet number per node
- 0
- Spikelet pedicel
- the spikelets have pedicels
- Spikelet position
- the spikelets emerge from both the upper and lower halves of the inflorescence branches
- Spikelet shape
-
- the spikelets are elliptic (widest in the middle, tapering to the ends) in profile
- the spikelets are obovate (egg-shaped but with the widest point above the middle) in profile
- 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 length
- 1.3–2.3 mm
- 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
-
Fruits or seeds
- Seed length
- 1.2–1.4 mm
-
Growth form
- Horizontal rooting stem
- no
- Lifespan
-
- the plant lives more than two years
- 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
- 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 hairy
- Leaf blade length
- 1.5–9 cm
- Leaf blade width
- 3–5 mm
- Leaf ligule length
- 0.6–2.5 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 hairs
-
- there are hairs on the surface of the leaf sheath
- there are no hairs on the surface of the leaf sheath
-
Place
- Habitat
- terrestrial
- New England state
-
- Connecticut
- Maine
- Massachusetts
- New Hampshire
- Rhode Island
- Vermont
- Specific habitat
- man-made or disturbed habitats
-
Stem, shoot, branch
- Hairs at nodes
- the stem nodes are hairless or they have very sparse hairs
- Plant height
- 20–70 cm
- Roots at lower stem nodes
-
- no
- yes
- Stem hairs
- the stem is nearly to completely hairless
- Stem node number
- 3–4
- Stem orientation
- the stems trail at the base, but turn upwards at the tips
- Stem spacing
- the stems grow close together in compact clusters or tufts
Wetland status
Usually occurs in non-wetlands, but occasionally in wetlands. (Wetland indicator code: FACU)
New England distribution and conservation status
Distribution
- Connecticut
- present
- Maine
- present
- Massachusetts
- present
- New Hampshire
- present
- Rhode Island
- present
- Vermont
- present
Conservation status
Exact status definitions can vary from state to state. For details, please check with your state.
- Maine
- unranked (S-rank: SNR)
- Massachusetts
- not applicable (S-rank: SNA)
Native to North America?
No
Sometimes confused with
- Digitaria filiformis:
- axis of panicle branches triquetrous, but not wing-margined, and reproductive stems usually upright, only rarely rooting at the lower nodes (vs. D. ischaemum, with the axis of panicle branches wing-margined and reproductive stems usually decumbent and rooting from the lower nodes).
- Digitaria sanguinalis:
- lower glume present and 0.2-0.4 mm long and upper lemma yellow to gray or brown (vs. D. ischaemum, with the lower glume absent or a tiny, membranous rim and upper lemma dark purple-brown).
Synonyms
- Panicum ischaemum Schreb.
Family
Genus
From the dichotomous key of Flora Novae Angliae
3. Digitaria ischaemum (Schreb.) Muhl. E
smooth crabgrass. Panicum ischaemum Schreb. • CT, MA, ME, NH, RI, VT. Roadsides, yards, railroads, lawns, sandy, disturbed soil.