Lycopodiella are non-flowering plants. They have leafy rhizomes that grow along the ground and vertical, leafy shoots, also known as peduncles.^[4] Fertile peduncles have strobili at the top of the shoot.^[4] Individuals can have short, creeping rhizomes with simple strobili, branching rhizomes with many strobili, or anywhere in between.^[1] The North American specimens are typically shorter, have thinner shoots, and have fewer vertical shoots in the North than specimen in the South.^[5]

Lycopodiella life cycles include an independent sporophyte stage and a long-lived gametophyte stage.^[6] Individuals reproduce by single-celled spores that disperse and germinate into small plants when in suitable conditions.^[2] This part of the plant is called the gametophyte; it produces the eggs and sperm.^[2] In Lycopodiella the gametophytes grow on the surface of the soil and are partially photosynthetic.^[7] After fertilization, the embryos grow into sporophytes, which are larger spore-bearing plants.^[2] The sporophyte is the vegetative part of the plant seen in nature. Juvenile individuals typically re-sprout in the spring or after a fire.^[4] Individuals have a base chromosome number of 78.^[8]

In the Pteridophyte Phylogeny Group classification of 2016 (PPG I), Lycopodiella is placed in the subfamily Lycopodielloideae, along with three other genera (Lateristachys, Palhinhaea and Pseudolycopodiella).^[3] In 2022, an additional monotypic genus, Brownseya, was segregated from Pseudolycopodiella to render the latter monophyletic.^[9] Other sources do not recognize these genera, submerging them into Lycopodiella.^[10][11]

As of February 2023^[update], the Checklist of Ferns and Lycophytes of the World recognized the following species:^[12]

• Lycopodiella alopecuroides (L.) Cranfill – foxtail clubmoss; North and South America
• Lycopodiella andicola B.Øllg. - northern Andes Mountains
• Lycopodiella appressa (Chapm.) Cranfill – southern clubmoss, appressed bog clubmoss; eastern North America, Cuba
• Lycopodiella duseniana (B.Øllg. & P.G.Windisch) B.Øllg. - Brazil
• Lycopodiella geometra B.Øllg. & P.G.Windisch – southern South America
• Lycopodiella inundata (L.) Holub – marsh clubmoss or bog clubmoss; circumboreal cool temperate
• Lycopodiella longipes (Hook. & Grev.) Holub – Central and South America, Cuba
• Lycopodiella margueriteae J.G.Bruce – northern prostrate clubmoss; central and eastern United States
• Lycopodiella mathewsii (Hook.) Holub – northern South America
• Lycopodiella prostrata (R.M.Harper) Cranfill – feather stem clubmoss; southeastern United States
• Lycopodiella subappressa J.G.Bruce, W.H.Wagner & Beitel – northern appressed clubmoss; central and eastern United States
• Lycopodiella tupiana (B.Øllg. & P.G.Windisch) B.Øllg. – southern South America

Some hybrids have also been described:^[12]

• Lycopodiella × brucei Cranfill
• Lycopodiella × copelandii (Eiger) Cranfill
• Lycopodiella × gilmanii A.Haines
• Lycopodiella × robusta (R.J.Eaton) A.Haines

Lycopodiella is found worldwide, but typically in temperate and tropical areas, a majority of which are found in North and South America.^[13] Individuals are typically found in terrestrial lowlands or montane forests on poor soils.^[14] Much of the soils are sandy and saturated and have little to no organic layer.^[2]

North America edit

The known Lycopodiella in North America consists of six species and four hybrids.^[15] All but one species of Lycopodiella, Lycopodiella inundata, are limited to the East coast, Gulf of Mexico, and/or Great Lakes region.^[15] L. inundata is found from New England to Alaska and down into California.^[15]

• Genus description