RI Equisetopsida, Lycopodiopsida and Isoetopsida

Horsetails, Club-mosses, Fir-mosses, Spike-mosses and Quillworts

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.

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 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.

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.

For a key to the status codes, click here.

To download a PDF (3.59MB) of RI Equisetopsida, Lycopodiopsida, and Isoetopsida click here.

Special Thanks

Thank you 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.

Horsetails

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
Counties found in: All

Botanical Name: Equisetum fluviatile
Common Name: Water Horsetail
Habitat: In water, marshes, ponds
Spores Found: May(8-)25 – July 4(-19)
State Status: SC
Counties found in: Providence, Washington
Number of RI sites: 3

Photo credits: Robbin Moran, NY Botanical Garden.

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
Counties found in: Providence, Kent, Washington
Number of RI sites: 7

Botanical Name: Equisetum sylvaticum
Common Name: Woodland Horsetail
Habitat: Moist woods and swampy areas
Spores Found: (June21-)July11 – Aug.12(-20)
State Status: SC
Counties found in: Providence, Bristol, Washington
Number of RI sites: 10

Photo credits: Robbin Moran, NY Botanical Garden.

Botanical Name: Equisetum variegatum
Common Name: Variegated Horsetail
Habitat: Moist sandy soil
Spores Found: June – Sept
State Status: SE
Counties found in: Kent(?)
Number of RI sites: 1

Photo credits: Robbin Moran, NY Botanical Garden.

Clubmosses

Botanical Name: Dendrolycopodium hickeyi
Common Name: Hickey’s Tree Clubmoss
Habitat: Hardwood forests in acid soil.
Spores Found: –
State Status: C
Counties found in: All
Number of RI sites: –

Photo credit: Robbin Moran, NY Botanical Garden.

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
Counties found in: All
Number of RI sites: –

Photo credit: Robbin Moran, NY Botanical Garden.

Botanical Name: Diphasiastrum digitatum
Common Name: Southern Ground Cedar or Creeping Jenny
Habitat: Dry woods.
Spores Found: Aug 20 – Sept 19
State Status: C
Counties found in: All
Number of RI sites: –

Photo credit: Jaknouse [CC-BY-SA-3.0 (http://creativecommons.org/licenses/ by-sa/3.0)], via Wikimedia Commons

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
Counties found in: All
Number of RI sites: –

Photo credit: kbarton

Botanical Name: Lycopodiella alopecuroides
Common Name: Fox-tail Clubmoss
Habitat: Wet sandy areas and bogs.
Spores Found: July – Oct
State Status: SE
Counties found in: Providence, Kent, Washington
Number of RI sites: 3

Photo credit: Robbin Moran, NY Botanical Garden.

Botanical Name: Lycopodiella appressa
Common Name: Apressed or Bog Clubmoss
Habitat: Bogs, borrow pits, wet sandy soil.
Spores Found: –
State Status: R
Counties found in: Providence
Number of RI sites: –

Photo credit: Robbin Moran, NY Botanical Garden.

Botanical Name: Lycopodiella inundata
Common Name: Northern Bog Clubmoss
Habitat: Bogs, marshes, wet sands.
Spores Found: July 20 – Nov 12
State Status: U
Counties found in: All
Number of RI sites: –

Photo credit: Robbin Moran, NY Botanical Garden.

Botanical Name: Lycopodium clavatum
Common Name: Staghorn Clubmoss
Habitat: Moist woods and swamps.
Spores Found: July 2 – Sept 20
State Status: C
Counties found in: All
Number of RI sites: –

Photo credit: Robbin Moran, NY Botanical Garden.

Botanical Name: Lycopodium lagopus
Common Name: One-cone Clubmoss
Habitat: Open woods.
Spores Found: July 2 – Sept 20
State Status: SE
Counties found in: Providence
Number of RI sites: 1

Photo Credit: © Francis R. Underwood 2015

Botanical Name: Spinulum annotinum
Common Name: Bristly or Stiff Clubmoss
Habitat: Coniferous woods.
Spores Found: (June2-) July2 – Sept.26 (-Oct.13)
State Status: SE
Counties found in: Providence
Number of RI sites: 1

Photo Credit: © Francis R. Underwood 2015

Fir-mosses

Botanical Name: Huperzia lucidula
Common Name: Shining Club Moss
Habitat: Moist woods.
Spores Found: June 25 – Nov.
State Status: C
Counties found in: All
Number of RI sites: –

Photo credits: Robbin Moran, NY Botanical Garden.

Spike-mosses

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
Counties found in: Kent, Newport, Providence, Washington
Number of RI sites: 4

Photo credit: Robbin Moran, NY Botanical Garden.

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
Counties found in: Newport, Providence, Washington
Number of RI sites: 3

Photo credits: Robbin Moran, NY Botanical Garden.

Quillworts

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
Counties found in: Providence, Kent
Number of RI sites: 2

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.

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

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

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
Counties found in: Providence, Kent
Number of RI sites: 2

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

Botanical Name: Isoetes lacustris
Common Name: Lake Quillwort
Habitat: Submerged plant of acid waters.
Spores Found: July – Sept.
State Status: R
Counties found in: –
Number of RI sites: –

Photo 1: Robbin Moran, NY Botanical Garden.

Photo 2: Robbin Moran, NY Botanical Garden.

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

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

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
Counties found in: Providence, Kent
Number of RI sites: 4

Photo 1: Ann Larson, Missouri Botanical Garden.

Photo 2: Ann Larson, Missouri Botanical Garden.

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

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: R
Counties found in: Providence
Number of RI sites: 1

Photo 1: Robbin Moran, NY Botanical Garden.

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.

Photo 3: Ann Larson, Missouri Botanical Garden.

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
Counties found in: Providence
Number of RI sites: 0 (1942)