Digitaria filiformis — slender crabgrass
![Stems and sheaths: Digitaria filiformis. ~ By Mary Barkworth. ~ Copyright © 2024 Mary Barkworth. ~ Mary.Barkworth[at]usu.edu ~ Manual of Grasses for North America](https://newfs.s3.amazonaws.com/taxon-images-1000s1000/Poaceae/digitaria-filiformis-filiformis-ss-mbarkworth1.jpg)
![Plant form: Digitaria filiformis. ~ By West Virgina University Press. ~ Copyright © 2024 West Virgina University Press. ~ Carrie Mullen, carrie.mullen[at]mail.wva.edu ~ P.D. Strasbaugh and Earl L. Core, Flora of West Virginia. 1970. West Virginia U. Press, Morgantown, WV](https://newfs.s3.amazonaws.com/taxon-images-1000s1000/Poaceae/digitaria-filiformis-filiformis-ha-florawva1.jpg)
![Spikelets: Digitaria filiformis. ~ By Anna Gardner. ~ Copyright © 2024. ~ dlewis[at]ias.edu ~ Ada Hayden Herbarium - Iowa State U.](https://newfs.s3.amazonaws.com/taxon-images-1000s1000/Poaceae/digitaria-filiformis-filiformis-si-agardner.jpg)
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Facts
Slender crabgrass is native to southern and eastern North America. In New England there are two varieties. One (Digitaria filiformis var. laeviglumis) is rare and endemic to New Hampshire, where it is found in peaty depressions on granite ledges. The other (D. filiformis var. filiformis) is a more widespread inhabitant of dry, open, sandy areas.
Habitat
Anthropogenic (man-made or disturbed habitats), grassland, meadows and fields, ridges or ledges
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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enlargeCharacteristics
- Habitat
-
- terrestrial
- wetlands
- New England state
-
- Connecticut
- Massachusetts
- New Hampshire
- Rhode Island
- Leaf blade width
- 1–6 mm
- Inflorescence branches
- the flowers are attached to branches rather than to the main axis of the inflorescence
- Spikelet length
- 1.3–2.8 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
- there is one floret per spikelet
- Lemma awn length
- 0 mm
- Leaf sheath hair type
-
- there are hairs on the surface of the leaf sheath, and some of the hairs have blisters at their bases
- there are no hairs on the surface of the leaf sheath
- Leaf ligule length
- 0.3–1.5 mm
- Anther length
- 0.3–0.6 mm
-
Flowers
- Anther length
- 0.3–0.6 mm
- Anther number
- 3
- Awn on glume
- the glume has no awn
- Bristles below spikelets
- no
- Floret lower bract texture
- the lemma is hard and firm
- Floret number
- 1–2
- Floret types within spikelet
-
- NA
- there are at least two distinct forms of florets within one spikelet
- Glume relative length
- neither glume is quite as long as all of the florets
- Glume shape
- the glume is flat or curved in cross-section
- Glume veins
-
- 0
- 1
- 3
- 5
- 7 or more
- Inflorescence arrangement
- the spikelets are uniform
- Inflorescence axis orientation
- the inflorescence axis is straight
- Inflorescence branches
- the flowers are attached to branches rather than to the main axis of the inflorescence
- 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
- 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 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
- One or more florets
-
- there is more than one floret per spikelet
- there is one floret per spikelet
- Palea relative length
- palea is one half to fully as long as lemma
- Spikelet axis tip
- there is no extension of the spikelet axis beyond the tip of the spikelet
- Spikelet length
- 1.3–2.8 mm
- Spikelet pedicel
- the spikelets have pedicels
- Spikelets spiny
- the spikelets do not appear spiny
- Upper glume shape
- the upper glume is widest at or below the middle
-
Leaves
- Leaf auricles
- the leaves do not have auricles
- Leaf blade width
- 1–6 mm
- Leaf ligule length
- 0.3–1.5 mm
- Leaf ligule type
- the leaf ligule is in the form of a membrane
- 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, and some of the hairs 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
-
Place
- Habitat
-
- terrestrial
- wetlands
- New England state
-
- Connecticut
- Massachusetts
- New Hampshire
- Rhode Island
- Specific habitat
-
- grasslands
- man-made or disturbed habitats
- meadows or fields
- ridges or ledges
-
Stem, shoot, branch
- Roots at lower stem nodes
-
- no
- yes
- 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
Wetland status
Not classified
In New England
Distribution
- Connecticut
- present
- Maine
- absent
- 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.
- Massachusetts
- widespread (S-rank: S5)
var. filiformis
- New Hampshire
- historical (S-rank: SH), endangered (code: E)
var. laeviglumis
- New Hampshire
- historical (S-rank: SH), endangered (code: E)
From Flora Novae Angliae dichotomous key
2. Digitaria filiformis (L.) Koel. NC
slender crabgrass. 2a. Digitaria laeviglumis Fern.; 2b. Panicum filiforme L. • CT, MA, NH,RI. Dry, open, often sandy, areas, such as fields, roadsides, and disturbed lots, also in peaty depression on granitic ledges. Digitaria filiformis resembles D. ischaemum and D. violascens in several character states, including the highly reduced lower glume, relative length of the upper glume, and color of the upper lemma. In addition to characters stated in the key, D. filiformis differs from the two mentioned species in its pustulose-based hairs on the lower sheaths (vs. glabrous to sparsely pubescent).
1a. Lower lemmas glabrous … 2a. D. filiformis var. laeviglumis (Fern.) Wippf
1b. Lower lemmas pubescent … 2b. D. filiformis var. filiformis
Variety laeviglumis is known from (and endemic to) NH. It is of regional conservation concern and occurs in peaty depressions on granitic ledges in Hillborough County. Variety filiformis is known from CT, MA, NH, RI.
Native to North America?
Yes
Sometimes confused with
- Digitaria ischaemum:
- axis of panicle branches wing-margined and reproductive stems usually decumbent and rooting from the lower nodes (vs. D. filiformis, with the axis of panicle branches triquetrous, but not wing-margined, and reproductive stems usually upright, only rarely rooting at the lower nodes).
Synonyms
- Panicum filiforme L.