Isoetes riparia — Canada shore quillwort
![Shoots: Isoetes riparia. ~ By Lytton John Musselman. ~ Copyright © 2024 lmusselm[at]odu.edu; http://www.odu.edu/~lmusselm/. ~ lmusselm[at]odu.edu ~ www.odu.edu/~lmusselm/plant/](https://newfs.s3.amazonaws.com/taxon-images-1000s1000/Isoetaceae/isoetes-riparia-sh-lmusselman1.jpg)
![Inflorescences: Isoetes riparia. ~ By George Yatskievych. ~ Copyright © 2024 George Yatskievych. ~ george.yatskievych[at]mobot.org](https://newfs.s3.amazonaws.com/taxon-images-1000s1000/Isoetaceae/isoetes-riparia-in-gyatskievych1.jpg)
![Branches: Isoetes riparia. ~ By Robbin Moran. ~ Copyright © 2024 Robbin Moran. ~ rmoran[at]nybg.org ~ Plant Systematics - www.plantsystematics.org/](https://newfs.s3.amazonaws.com/taxon-images-1000s1000/Isoetaceae/isoetes-riparia-br-rmoran.jpg)
![Leaves: Isoetes riparia. ~ By Robbin Moran. ~ Copyright © 2024 Robbin Moran. ~ rmoran[at]nybg.org ~ Plant Systematics - www.plantsystematics.org/](https://newfs.s3.amazonaws.com/taxon-images-1000s1000/Isoetaceae/isoetes-riparia-le-rmoran.jpg)
![Flowers and fruits: Isoetes riparia. ~ By Lytton John Musselman. ~ Copyright © 2024 lmusselm[at]odu.edu; http://www.odu.edu/~lmusselm/. ~ lmusselm[at]odu.edu ~ www.odu.edu/~lmusselm/plant/](https://newfs.s3.amazonaws.com/taxon-images-1000s1000/Isoetaceae/isoetes-riparia-ff-lmusselman1.jpg)
![Stems: Isoetes riparia. ~ By George Yatskievych. ~ Copyright © 2024 George Yatskievych. ~ george.yatskievych[at]mobot.org](https://newfs.s3.amazonaws.com/taxon-images-1000s1000/Isoetaceae/isoetes-riparia-st-gyatskievych1.jpg)
![Spore cones: Isoetes riparia. ~ By George Yatskievych. ~ Copyright © 2024 George Yatskievych. ~ george.yatskievych[at]mobot.org](https://newfs.s3.amazonaws.com/taxon-images-1000s1000/Isoetaceae/isoetes-riparia-sc-gyatskievych1.jpg)
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Facts
Canada shore quillwort inhabits sandy and muddy margins of streams and lakes, including tidal shorelines. It is rare in our region, but is at least historically known from every New England state.
Habitat
Brackish or salt marshes and flats, fresh tidal marshes or flats, 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.
enlargeCharacteristics
- Habitat
-
- aquatic
- wetlands
- New England state
-
- Connecticut
- Maine
- Massachusetts
- New Hampshire
- Rhode Island
- Vermont
- Leaf shape
- the vegetative leaves are long and narrow
- Spore leaf arrangement
- the sporophylls are located in a whorl at the base of the plant
- Form of shoot
- NA
- Horizontal stem
- NA
- Leaf differences
- the vegetative leaves within a node are all similar in size and shape
- Teeth on leaf edges
- the edges of the vegetative leaves have no teeth
- Spore leaf length
- 350–500 mm
- Leaf outline
- the vegetative leaves are long and very narrow (linear)
-
Clonal plantlets
- Gemma arrangement
- NA
- Gemma shape
- NA
- Gemma width
- 0 mm
-
Leaves
- Leaf differences
- the vegetative leaves within a node are all similar in size and shape
- Leaf length
- 350–500 mm
- Leaf orientation
- the vegetative leaves spread slightly away from the stem, at a steep angle
- Leaf outline
- the vegetative leaves are long and very narrow (linear)
- Leaf ranks
- NA
- Leaf shape
- the vegetative leaves are long and narrow
- Spore leaf length
- 350–500 mm
- Teeth on leaf edges
- the edges of the vegetative leaves have no teeth
-
Place
- Habitat
-
- aquatic
- wetlands
- New England state
-
- Connecticut
- Maine
- Massachusetts
- New Hampshire
- Rhode Island
- Vermont
- Specific habitat
-
- brackish or salt marshes and flats
- fresh tidal marshes or flats
- shores of rivers or lakes
-
Spores or spore cones
- Cone base at stem
- NA
- Cone stalk branching
- NA
- Cone thickness
- 0 mm
- Cone width
- 0 mm
- Length of cone
- 0 mm
- Number of cones
- 0
- Quillwort itssue covering spores
- the velum covers less than half of the spores
- Same or different spores
- there are two different types of spores present
- Spore diameter
- 0.4499–0.6499
- Spore girdle
- there is no girdle alongside the equatorial ridge
- Spore leaf arrangement
- the sporophylls are located in a whorl at the base of the plant
- Spore leaf lifespan
- the sporophylls remain green for the life of the plant
- Spore leaf orientation
- the sporophylls slant upwards at a steep angle
- Spore leaf shape
- the spore-bearing leaves are long and narrow
- Spore leaf teeth
- The edges of the spore-bearing leaves are smooth, and without teeth
- Spore texture
- the spore surface is crested with a narrow irregular ridge (cristate)
- Sporophyll ranks
- NA
- Sterile tip of cone
- NA
-
Stem, shoot, branch
- Branch cross-section
- NA
- Branch form
- NA
- Constriction zones
-
- NA
- NA
- Form of shoot
- NA
- Horizontal stem
- NA
- Horizontal stem length
- 0 mm
- Horizontal stem thickness
- 0 mm
- Stem height
- 0 mm
Wetland status
Occurs only in wetlands. (Wetland indicator code: OBL)
In New England
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.
- Connecticut
- uncommon (S-rank: S3)
- Maine
- historical (S-rank: SH), potentially extirpated (code: PE)
- Massachusetts
- unranked (S-rank: SNR)
- Vermont
- rare (S-rank: S2)
var. amesii
- Massachusetts
- unranked (S-rank: SNR)
var. canadensis
- New Hampshire
- extremely rare (S-rank: S1), endangered (code: E)
- Rhode Island
- extremely rare (S-rank: S1), concern (code: C)
var. riparia
- Massachusetts
- unranked (S-rank: SNR)
From Flora Novae Angliae dichotomous key
7. Isoetes riparia Engelm. ex A. Braun var. canadensis Engelm. ex N.E. Pfeiff. N
Canada shore quillwort. Isoetes canadensis (Engelm.) A.A. Eat. ex Maxon, nom. illeg. • CT, MA, ME, NH, RI, VT. Sandy and muddy margins of streams and lakes, including tidal shorelines. Isoetes riparia var. canadensis is an allotetraploid, formed by chromosome doubling in I. ×eatonii, which is the first generation hybrid between I. echinospora and I. engelmannii. See Caplen and Werth (2000) for justification of recognizing northern populations of the I. riparia complex as distinct. Unfortunately, no combination at the specific level has yet been made.
2×7. Isoetes echinospora × Isoetes riparia → Isoetes ×dodgei A.A. Eat. is a rare quillwort hybrid known from NH, VT. It shows spiny megaspores, but many of the spines are fused and/or irregular, resulting in a convoluted-echinate surface (i.e., the spines are not as regular in appearance as those in I. echinospora). The well-formed megaspores are usually smaller than 0.54 mm in diameter.
3×7. Isoetes engelmannii × Isoetes riparia → Isoetes ×brittonii D.F. Brunton & W.C. Taylor is documented from only CT in New England. It has megaspores with ornamentation very similar to those of I. engelmannii, except that the ridges forming the reticulum are broken in places and get more congested toward the equatorial ridge (similar to I. riparia). The well-formed megaspores measure 0.47–0.56 mm in diameter.
7×8. Isoetes riparia × Isoetes tuckermanii → Isoetes ×novae-angliae D.F. Brunton & D.M. Britt. is a rare quillwort hybrid known from CT, MA, NH. It has polymorphic megaspores, the well-formed ones measuring mostly 0.45–0.53 mm in diameter and having a dense, broken reticulum, showing an obscure girdle of congested reticulum (no spine-like papillae as occur in I. tuckermanii).
Native to North America?
Yes