Introduction

Formerly known as fern allies, Horsetails, Club-mosses, Fir-mosses, Spike-mosses and Quillworts are plants that have an alternate generation life-cycle similar to ferns, having both sporophyte and gametophyte stages.

Equisetopsida
Horsetails date from the Devonian period (416 to 359 million years ago) in earth’s history where they were trees up to 110 feet in height and helped to form the coal deposits of the Carboniferous period. Only one genus has survived to modern times (Equisetum).

Horsetails
Horsetails (Equisetum) have jointed stems with whorls of thin narrow leaves. In the sporophyte stage, they have a sterile and fertile form. They produce only one type of spore. While the gametophytes produced from the spores appear to be plentiful, the successful reproduction of the sporophyte form is low with most Horsetails reproducing vegetatively.

Lycopodiopsida
Lycopodiopsida includes the clubmosses (Dendrolycopodium, Diphasiastrum, Lycopodiella, Lycopodium, Spinulum) and Fir-mosses (Huperzia)

Clubmosses
Clubmosses are evergreen plants that produce only microspores that develop into a gametophyte capable of producing both sperm and egg cells. Club-mosses can produce the spores either in leaf axils or at the top of their stems. The spore capsules form in a cone-like structures (strobili) at the top of the plants.

Fir-mosses
Fir-mosses differ from Club-mosses in that they do not develop sporangial cones and they grow in clusters rather than growing prostrate along the ground.

Isoetopsida
The Isopsida (Spike-mosses and Quillworts) differ from the club-mosses in the development of male (microspores) and female (macrospores) spores.

Spike-mosses
Spike mosses (Selaginella) are similar to club-mosses with tiny leaves but differ from the clubmosses in having two types of spores and are actually more closely related to the Quillworts. Spike mosses have megaspores (usually only 4) which germinate into female gametophytes and numerous microspores which develop in to male gametophytes.

Quillworts
Quillworts (Isoetes) look similar to grasses, but this is an adaptation to their aquatic environment. They form two types of spores. In common with the Spike-mosses and clubmosses, the spores are produced at the base specialized leaves. With the Quillwort, the earliest leaves of a season produce megaspores that grow into female gametophytes whiles later leaves produce microspores that develop into male gametophytes.

Special Thanks

to the following
for giving permission for the use their images.

Robbin Moran
New York Botanical Garden

George Yatskievych and Ann Larson
Missouri Botanical Garden

Jan De Laet,
plantsystematics.org.

 

The information on Rhode Island Horsetails, Club-mosses, Fir-mosses, Spike-mosses and Quillworts comes from several sources. The dates for mature spores are based on Seymour's "Flora of New England". The county and status information is from Rick Enser's Rare Plants of RI and, for plants not on the Rare Plant List, the status is taken from Gil George's Rhode Island Botanical Survey Check List, published in 1999. Francis Underwood provided habitat information.

Table of Contents

For a key to the status codes, click here.

To down load a pdf (3.59 mb)of
RI Equisetopsida, Lycopodiopsida, and Isoetopsida
click here.

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Click on the thumbnail image to view a larger photo.
Horsetails

 

Common Horsetail close-up
Botanical Name:
   Equisetum arvense
Common Name:
   Common Horsetail
   
Habitat:
   Dry or wet soil, fields, woods and swamps
Spores found:
   Apr.14-June 4.
 
State Status:
   SC
Sites in State:
   —
Counties w/sites
   All

Common Horsetail fruiting body

Upper photo credit: Robbin Moran, NY Botanical Garden.

Lower photo credit: Jan De Laet, plantsystematics.org

 

 
     
 


Water Horsetail

Botanical Name:
   Equisetum fluviatile
Common Name:
   Water Horsetail
   
Habitat:
   In water, marshes, ponds
Spores found:
   May(8-)25-July 4(-19)
 
State Status:
   SC
Sites in State:
   3
Counties w/sites
   Providence, Washington
Water Horsetail close-up of stem
Photo credits: Robbin Moran, NY Botanical Garden.

Smooth Scouring Rush
Botanical Name:
   Equisetum hyemale ssp. affine
Common Name:
   Smooth Scouring Rush
   
Habitat:
   Dry or moist soil, roadsides, stream banks
Spores found:
   May(15-)19-Sept.2(-Oct.5)
 
State Status:
   SC
Sites in State:
   7
Counties w/sites
   Providence, Kent, Washington

Smooth Scouring Rush close-up

Upper photo credit: By Kondidresher (zdjęcie własne) [CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons

Lower photo credit: By Caromallo (Own work) [CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons

 

Woodland Horsetail
Botanical Name:
   Equisetum sylvaticum
Common Name:
   Woodland Horsetail
   
Habitat:
   Moist woods and swampy areas
Spores found:
   (June21-)July11-Aug.12(-20)
 
State Status:
   SC
Sites in State:
   10
Counties w/sites
   Providence, Bristol, Washington
Woodland Horsetail close-up
Photo credits: Robbin Moran, NY Botanical Garden.

Variegated Horsetail
Botanical Name:
   Equisetum variegatum
Common Name:
   Variegated Horsetail
   
Habitat:
   Moist sandy soil
Spores found:
   June-Sept
 
State Status:
   SE
Sites in State:
   1
Counties w/sites
   Kent (?)
Close up Variegated Horsetail
Photo credits: Robbin Moran, NY Botanical Garden.
Clubmosses
Hickey's Tree Clubmoss
Botanical Name:
   Dendrolycopodium hickeyi
Common Name:
   Hickey's Tree Clubmoss
   
Habitat:
   Hardwood forests in acid soil.
Spores found:
   —
 
State Status:
   C
Sites in State:
   —
Counties w/sites
   All
Photo credit: Robbin Moran, NY Botanical Garden.
Flat-branched Clubmoss or Prince's Pine
Botanical Name:
   Dendrolycopodium obscurum
Common Name:
   Flat-branched Clubmoss or Prince's Pine
   
Habitat:
   Hardwood forests, also sometimes in dry open areas.
Spores found:
   July 5-Oct.13
 
State Status:
   C
Sites in State:
   —
Counties w/sites
   All
Photo credit: Robbin Moran, NY Botanical Garden.
Creeping Jenny or Southern Ground Cedar
Botanical Name:
   Diphasiastrum digitatum
Common Name:
   Southern Ground Cedar or Creeping Jenny
   
Habitat:
   Dry woods.
Spores found:
   Aug.20-.Sept.19
 
State Status:
   C
Sites in State:
   —
Counties w/sites
   All
By Jaknouse [CC-BY-SA-3.0 (http://creativecommons.org/licenses/ by-sa/3.0)], via Wikimedia Commons
Blue or Wiry Ground Cedar
Botanical Name:
   Diphasiastrum tristachyum
Common Name:
   Blue or Wiry Ground Cedar
   
Habitat:
   Dry, acid woods.
Spores found:
   July(7-)18-Oct.13
 
State Status:
   F
Sites in State:
   —
Counties w/sites
   All
Photo credit: kbarton
Fox-tail Clubmoss
Botanical Name:
   Lycopodiella alopecuroides
Common Name:
   Fox-tail Clubmoss
   
Habitat:
   Wet sandy areas and bogs
Spores found:
   July-Oct.
 
State Status:
   SE
Sites in State:
   3
Counties w/sites
   Providence, Kent, Washington
Photo credit: Robbin Moran, NY Botanical Garden.

Appressed or Bog Clubmoss

Botanical Name:
   Lycopodiella appressa
Common Name:
   Apressed or Bog Clubmoss
   
Habitat:
   Bogs, borrow pits, wet sandy soil.
Spores found:
   —
 
State Status:
   R
Sites in State:
  
Counties w/sites
   Providence
Apressed or Bog Clubmoss
Photo credits: Robbin Moran, NY Botanical Garden.


Northern Bog Clubmoss
Botanical Name:
   Lycopodiella inundata
Common Name:
   Northern Bog Clubmoss
   
Habitat:
   Bogs, marshes, wet sands.
Spores found:
   July 20-Nov.12.
 
State Status:
   U
Sites in State:
   —
Counties w/sites
   All
Northern Bog Clubmoss close-up
Photo credits: Robbin Moran, NY Botanical Garden.


Staghorn Clubmoss
Botanical Name:
   Lycopodium clavatum
Common Name:
   Staghorn Clubmoss
   
Habitat:
   Moist woods and swamps.
Spores found:
   July 2-Sept.20
 
State Status:
   C
Sites in State:
   —
Counties w/sites
   All
Staghorn Clubmoss close-up
Photo credits: Robbin Moran, NY Botanical Garden.

One-cone Clubmoss

 
Botanical Name:
   Lycopodium lagopus
Common Name:
   One-cone Clubmoss
   
Habitat:
   Open woods.
Spores found:
  

July 2-Sept. 20.
 
State Status:
   SE
Sites in State:
   1
Counties w/sites
   Providence
Photo Credit: © Francis R. Underwood 2015


Bristly or Stiff Clubmoss
Botanical Name:
   Spinulum annotinum
Common Name:
   Bristly or Stiff Clubmoss
   
Habitat:
   Coniferous woods.
Spores found:
  

(June2-) July2-Sept.26 (-Oct.13)
 
State Status:
   SE
Sites in State:
   1
Counties w/sites:
   Providence
Bristly or Stiff Clubmoss fruiting bodies
Photo credits: Robbin Moran, NY Botanical Garden.
Fir-mosses

Shining Club Moss

Botanical Name:
   Huperzia lucidula
Common Name:
   Shining Club Moss
   
Habitat:
   Moist woods.
Spores found:
   June 25-Nov.
 
State Status:
   C
Sites in State:
   —
Counties w/sites
   All
Shining Club Moss close up
Photo credits: Robbin Moran, NY Botanical Garden.
Spike-mosses
Meadow Spike-moss
Botanical Name:
   Selaginella apoda
Common Name:
   Meadow Spike-moss or Footless Spike-moss
   
Habitat:
   Wet meadows, swamps, stream banks
Spores found:
   7/16-10/18
 
State Status:
   R
Sites in State:
   4
Counties w/sites
   Kent, Newport, Providence, Washington
Photo credit: Robbin Moran, NY Botanical Garden.

Northern Spike-moss

Botanical Name:
   Selaginella rupestris
Common Name:
   Rock Spike-moss
   
Habitat:
   Dry soil on rocky outcroppings
Spores found:
   (4/27) 5/3-9/19 (10/8)
 
State Status:
   SC
Sites in State:
   3
Counties w/sites
   Newport, Providence, Washington
Northern Spike-moss with penny
Photo credits: Robbin Moran, NY Botanical Garden.
Quillworts

 

Pointed or Spiny-spored Quillwort

 
Botanical Name:
   Isoetes echinospora
Common Name:
   Pointed or Spiny-spored Quillwort
   
Habitat:
   Usually submerged plant of cool acid water in sand or mud.
Spores found:
   June (2-)28-Oct. 6(-12)
 
State Status:
   SC
Sites in State:
   2
Counties w/sites
   Providence, Kent

Comparison of Isoetes echinospora (left) and I. tuckermanii (right).

Photo 1: W. Carl Taylor. USDA NRCS. 1992. Western wetland flora: Field office guide to plant species. West Region, Sacramento. Courtesy of USDA NRCS Wetland Science Institute. [Public domain], via Wikimedia Commons

Photo 2: Robbin Moran, NY Botanical Garden. Comparison of Isoetes echinospora (left) and I. tuckermanii (right). The latter species has pale reddish leaves and more recurved leaves.
     

Megaspores of Isoetes echinospora

Photo 3: Robbin Moran, NY Botanical Garden. Megaspores of Isoetes echinospora (left) and I. riparia (right).

 
     

Herbarium speciment of Isoetes echinospora

Photo 4: By Neuchâtel Herbarium (Own work) [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons
     

Engelmann's Quillwort

 
Botanical Name:
   Isoetes engelmannii
Common Name:
   Engelmann's Quillwort
   
Habitat:
   Usually submerged plant of fresh water with muddy shores
Spores found:
   June 22-Oct.
 
State Status:
   SC
Sites in State:
   2
Counties w/sites
   Providence, Kent
Photo credit: W. Carl Taylor. USDA NRCS. 1995. Northeast wetland flora: Field office guide to plant species. Northeast National Technical Center, Chester. Courtesy of USDA NRCS Wetland Science Institute. [Public domain], via Wikimedia Commons

 

Lake Quillwort
Botanical Name:
   Isoetes lacustris
Common Name:
   Lake Quillwort
   
Habitat:
   Submerged plant of acid waters
Spores found:
   July-Sept.
 
State Status:
   R
Sites in State:
   —
Counties w/sites
   —

Lake Quillwort

From top—

photos 1 and 2: Robbin Moran, NY Botanical Garden.

 
     

Lake Quillwort

Photo 3: By W. Carl Taylor. USDA NRCS. 1995. Northeast wetland flora: Field office guide to plant species. Northeast National Technical Center, Chester. Courtesy of USDA NRCS Wetland Science Institute. [Public domain], via Wikimedia Commons
     

Lake Quillwort megaspores

Photo 4: Robbin Moran, NY Botanical Garden. Megaspores showing trilete markings on the proximal face.

 
     

River or Shore Quillwort

 

 
Botanical Name:
   Isoetes riparia
Common Name:
   River or Shore Quillwort
   
Habitat:
   Usually submerged plant of fresh or brackish water in gravel or mud
Spores found:
   July-Sept.
 
State Status:
   SC
Sites in State:
   4
Counties w/sites
   Providence, Kent
River or Shore Quillwort showing megaspores Top and center photos: Ann Larson, Missouri Botanical Garden.
     

River or Shore Quillwort close-up of megaspores

Bottom photo: Robbin Moran, NY Botanical Garden. Megaspores of Isoetes echinospora (left) and I. riparia (right)
     

 

Tuckerman's Quillwort
Botanical Name:
   Isoetes tuckermanii
Common Name:
   Tuckerman's Quillwort
   
Habitat:
   Submerged plant of acid water with sandy shores
Spores found:
   (June 10-)July 10-Oct 15
 
State Status:
   Rare
Sites in State:
   1
Counties w/sites
   Providence

Tuckerman's Quillwort

Top photo: Robbin Moran, NY Botanical Garden.

 

Center photo: Robbin Moran, NY Botanical Garden. Comparison of Isoetes echinospora (left) and I. tuckermanii (right). The latter species has pale reddish leaves and more recurved leaves.

 
     

Tuckerman's Quillwort showing megaspores

Bottom photo: Ann Larson, Missouri Botanical Garden.

 
     

No image
available
Botanical Name:
   Isoetes x eatonii
Common Name:
   Eaton’s Quillwort
   
Habitat:
   Submerged plant of acid water with sandy shores
Spores found:
  
Oct. 15
 
State Status:
   SH
Sites in State:
   0 (1942)
Counties w/sites
   Providence

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