Juncus debilis — weak rush
![Leaves and auricles: Juncus debilis. ~ By Troy University Herbarium. ~ Copyright © 2024. ~ Brian Keener, bkeener[at]uwa.edu ~ Troy U. Herbarium](https://newfs.s3.amazonaws.com:443/taxon-images-1000s1000/Juncaceae/juncus-debilis-la-troyherb1.jpg)
![Stems and sheaths: Juncus debilis. ~ By Troy University Herbarium. ~ Copyright © 2024. ~ Brian Keener, bkeener[at]uwa.edu ~ Troy U. Herbarium](https://newfs.s3.amazonaws.com:443/taxon-images-1000s1000/Juncaceae/juncus-debilis-ss-troyherb1.jpg)
Copyright: various copyright holders. To reuse an image, please click it to see who you will need to contact.
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.
enlargeFacts
Weak rush is a small rush, very rare in New England, with a few populations in the coastal areas of Connecticut, Massachusetts and Rhode Island. It occupies a number of low, wet habitats.
Habitat
Anthropogenic (man-made or disturbed habitats), meadows and fields, wetland margins (edges of wetlands)
Characteristics
- Habitat
- wetlands
- New England state
-
- Connecticut
- Massachusetts
- Rhode Island
- Stem shape in cross-section
- the stem is round or oval in cross-section
- Leaf blade width
- 0.5–1.5 mm
- Leaf blade cross-section
- the leaf blade is elliptic or circular in cross-section
- Inflorescence position
- the inflorescence is at the tip of the plant
- Inflorescence branching
- the inflorescence is branched
- Fruit type (general)
- the fruit is a capsule, with at least three seeds in it
- Fruit length
- 2.8–4.2 mm
- Leaf position on plant
-
- some leaf attachment points are above the midpoint of the stem
- the attachment points of all the leaves are at or near the base of the plant
- Perianth composition
- the perianth is green or brown, with six sepal-like parts, and a leafy texture
- Fruit cross-section
- the fruit is triangular to terete (circular) in cross-section
-
Flowers
- Anther color (dry)
- the anthers range in color from white to tan or yellow to yellow-brown
- Floral bristle color
- NA
- Floral bristle number
- NA
- Floral bristle relative length
- NA
- Floral bristles
- NA
- Floral scale hairs
- NA
- Floral scale length
- 0 mm
- Floral scale nerves
- NA
- Flower number per cluster
-
- 2-5
- 5-20
- Inflorescence bract angle
- the bracts are vertical or angled only slightly outwards
- Inflorescence bract number
- there are two to five bracts per inflorescence
- Inflorescence bract position (Sparganium)
- NA
- Inflorescence bracts
- there are at least two bracts, and they are either flat or folded or rolled in at the edges
- Inflorescence branching
- the inflorescence is branched
- Inflorescence crowding
- the inflorescence is at least somewhat spread out, with at least one branch coming from the main stem
- Inflorescence position
- the inflorescence is at the tip of the plant
- Inflorescence shape
- the aggregations within the inflorescence are roughly circular (not flattened) in cross-section
- Inflorescence type
- there are two or more flowers, spikes or flower clusters on a branched inflorescence
- Perianth composition
- the perianth is green or brown, with six sepal-like parts, and a leafy texture
- Stamen number
- 3
- Stigma number
- 3
- floral bristle barbs
- NA
-
Fruits or seeds
- Achene beak length
- 0 mm
- Achene surface texture
- NA
- Achene tubercle relative width
- NA
- Achene tubercle width
- 0 mm
- Capsule relative length
- the capsule is longer thant he perianth
- Fruit cross-section
- the fruit is triangular to terete (circular) in cross-section
- Fruit length
- 2.8–4.2 mm
- Fruit type (general)
- the fruit is a capsule, with at least three seeds in it
- Fruit type (specific)
- the fruit is a capsule (splits along two or more seams, apical teeth or pores when dry, to release two or more seeds)
- Locules in capsule
- the capsule has one locule
- Seed length
- 0.3–0.4 mm
- Seed tail relative length
- 0.3–0.4 mm
- Seed tails
- there is no tail on the seeds
- Tubercle height
- 0 mm
-
Growth form
- Lifespan
- the plant lives more than two years
- Underground organs
- the plant has a rhizome (a horizontal underground stem with roots growing from it)
-
Leaves
- Auricle length
- 1–1.5 mm
- Auricle texture
- the auricles are weak, papery and translucent
- Auricles
- the leaf sheath has auricles on it
- Leaf blade cross-section
- the leaf blade is elliptic or circular in cross-section
- Leaf blade length
- 10–125 mm
- Leaf blade width
- 0.5–1.5 mm
- Leaf form
- all the leaves hold their form out of water
- Leaf position on plant
-
- some leaf attachment points are above the midpoint of the stem
- the attachment points of all the leaves are at or near the base of the plant
- Leaf septa
- the leaf blades have transverse septa
- Leaf sheath hairs
- the leaf sheathes are without hairs
- Pedicel length (Typha)
- 0 mm
- Stem leaf blade ligules
- there are no ligules at the leaf blade bases
- Stem leaf blades
- there are fully-developed leaves with leaf blades on the main stem
- Width of seed-producing inflorescence
- 2–5 mm
-
Place
- Habitat
- wetlands
- New England state
-
- Connecticut
- Massachusetts
- Rhode Island
- Specific habitat
-
- edges of wetlands
- man-made or disturbed habitats
- meadows or fields
-
Stem, shoot, branch
- Plant height
- 10–25 cm
- Stem shape in cross-section
- the stem is round or oval in cross-section
- Stem texture near tip
- the stem feels smooth near the tip
- Stem thickness at midpoint
- 1–2 mm
Wetland status
Occurs only in wetlands. (Wetland indicator code: OBL)
New England distribution and conservation status
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
- historical (S-rank: SH), special concern, extirpated (code: SC*)
- Massachusetts
- extremely rare (S-rank: S1), endangered (code: E)
- Rhode Island
- historical (S-rank: SH), state historical (code: SH)
Native to North America?
Yes
Sometimes confused with
- Juncus acuminatus:
- tepals nearly or fully as long as the capsules and tepals 2.6-3.9 mm long (vs. J. debilis, with tepals evidently shorter than the mature capsules, 1.8-2.5 mm long).
- Juncus diffusissimus:
- capsules 4–5.2 mm long, approximately 2 times as long as the tepals (vs. J. debilis, with capsules mostly 2.8–3.7 mm long, approximately 1.3–1.5 times as long as the tepals).
Family
Genus
From the dichotomous key of Flora Novae Angliae
15. Juncus debilis Gray NC
weak rush. CT, MA, RI. Low areas in fields, edges of pools, roadside ditches, damp coastal sands.