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- Tripsacum dactyloides
Tripsacum dactyloides — eastern gamagrass
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Facts
Eastern gamagrass inhabits Central and South America and the eastern, southern and central United States, reaching the northeastern limit of its range in New England. In our region it is a very rare grass of the upper edges of salt marshes, salt meadows, riversides and fields near the coast. It can reach heights near 3 m (10 feet), and is increasingly popular as a garden ornamental.
Habitat
Anthropogenic (man-made or disturbed habitats), marshes, meadows and fields, shores of rivers or lakes
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
- wetlands
- New England state
-
- Connecticut
- Massachusetts
- Rhode Island
- Leaf blade width
- 9–45 mm
- Inflorescence branches
-
- the flowers are attached to branches rather than to the main axis of the inflorescence
- there are no branch points between the base of the inflorescence axis and the flowers, or they are not obvious
- Spikelet length
- 6–8 mm
- Glume relative length
- 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 one floret per spikelet
- Lemma awn length
- 0 mm
- Leaf ligule length
- 1–3 mm
-
Flowers
- Anther number
- At least 0
- Awn on glume
- the glume has no awn
- Floret types within spikelet
- there are at least two distinct forms of florets within one spikelet
- Glume relative length
- 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
- Inflorescence arrangement
- the plant has two types of spikelets with different reproductive structures
- Inflorescence axis orientation
-
- the inflorescence axis is arched or curved outward
- the inflorescence axis is straight
- Inflorescence branches
-
- the flowers are attached to branches rather than to the main axis of the inflorescence
- there are no branch points between the base of the inflorescence axis and the flowers, or they are not obvious
- Inflorescence type (general)
-
- the inflorescence is a spike, or is spike-like, lacking obvious branches
- the spikelets are borne on stalks or on branches
- Inflorescence type (specific)
-
- the inflorescence has pairs (or trios) of spikelets that are similar to each other in structure and size, with at least one of the spikelets on a stalk
- the inflorescence has pairs (or trios) of spikelets, but with one always either missing a stalk or on a shorter stalk than the other
- 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
- NA
- Lemma awn length
- 0 mm
- Lemma awn number
- the lemma has no awn
- 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
- 0
- One or more florets
- there is one floret per spikelet
- 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
- 6–8 mm
- Spikelets spiny
- the spikelets do not appear spiny
-
Leaves
- Leaf auricles
- the leaves do not have auricles
- Leaf blade width
- 9–45 mm
- Leaf ligule length
- 1–3 mm
- Leaf ligule type
- the leaf ligule is in the form of a membrane with fine hairs
- 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
- wetlands
- New England state
-
- Connecticut
- Massachusetts
- Rhode Island
- Specific habitat
-
- man-made or disturbed habitats
- marshes
- meadows or fields
- shores of rivers or lakes
-
Stem, shoot, branch
- 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
Occurs in wetlands or non-wetlands. (Wetland indicator code: FAC)
In New England
Distribution
- Connecticut
- present
- Maine
- absent
- Massachusetts
- present
- New Hampshire
- absent
- Rhode Island
- present
- Vermont
- absent
Conservation status
Exact status definitions can vary from state to state. For details, please check with your state.
- Connecticut
- uncommon to fairly widespread (S-rank: S3S4)
- Massachusetts
- extremely rare (S-rank: S1), endangered (code: E)
- Rhode Island
- rare (S-rank: S2), concern (code: C)
From Flora Novae Angliae dichotomous key
1. Tripsacum dactyloides (L.) L. NC
eastern gamagrass. Coix dactyloides L. • CT, MA, RI. Upper border of saline marshes, salt meadows, river shores and banks, dry fields near the coast.
Native to North America?
Yes
Sometimes confused with
- Aegilops cylindrica:
- leaf blades mostly 2-5 mm long and inflorescence a spike, 2.2-12 cm tall (vs. T. dactyloides, with leaf blades mostly 9-35 mm wide and inflorescence a rame, 12-25 cm tall).
Synonyms
- Coix dactyloides L.