Southern Ground Cedar Diphasiastrum digitatum (Dillenius ex A. Braun) Holub    Synonyms: Fan Clubmoss, Groundcedar, Lycopodium complanatum var. flabelliforme, Lycopodium digitatum, Lycopodium flabelliforme, Running Cedar.
Kingdom Plantae   >   Division Lycopodiophyta   >   Class Lycopodiopsida   >   Order Lycopodiales   >   Family Lycopodiaceae   >   Genus Diphasiastrum   

Status:

Southern Ground Cedar occurs across eastern North America, and can be found throughout Maryland. Spreading by rhizomes, or horizontal stems, that are at or near the soil surface, it can form large patches. It is very slow-growing, and formerly was harvested for Christmas decorations, leading to its depletion in some forests. It should not be harvested, and transplants seldom survive.

Description:

This species spreads to new habitats by releasing spores from clusters of yellowish strobili (cone-like structures) at the tips of the plant, typically during late summer or autumn.

Southern Ground Cedar can be confused with the uncommon Blue Ground Cedar (Diphasiastrum tristachyum). To differentiate the two species you need to look at a variety of features. First check out the horizontal stems. Southern Ground Cedar has horizontal stems that are right on the surface of the ground or just under the surface. Blue Ground Cedar has horizontal stems that can be found up to 12cm under the ground. Next look at the coloration of the vertical parts of the plant. Southern Ground Cedar is typically dark green and not glaucous while Blue Ground Cedar, like its name, is blue-green and glaucous. Next check out the branchlets. Southern Ground Cedar lacks annual constrictions on the branchlets while Blue Ground Cedar typically has obvious annual constrictions on the branchlets.

Where to find:

Southern Ground Cedar occurs in mesic to dry acidic forests, old fields, and clearings. It is especially common in successional pine and Tulip-tree forests (Weakley, et al., 2012), and thus is a good indicator of past disturbance of a site (R. Simmons, pers. comm.).

Because clubmoss species are evergreen, winter is the best time to search for them; they are often the only green plants growing on the forest floor.

Relationships:

The foliage of clubmosses contains toxic alkaloids, so is usually avoided by mammalian herbivores (Illinois Wildflowers website). Clubmosses are one of the forest-floor plants that provide protective cover for the ground-nesting Nashville Warbler (Harrison, 1975).

There are 372 records in the project database.

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Southern Ground Cedar growing in Garrett Co., Maryland (10/31/2009). Photo by Jim Brighton. (MBP list)

Southern Ground Cedar in Montgomery Co., Maryland (10/23/2016). Photo by Bill Hill. (MBP list)

Southern Ground Cedar in Howard Co., Maryland (5/1/2014). Photo by Nancy Magnusson. (MBP list)

Southern Ground Cedar in Anne Arundel Co., Maryland (11/12/2017). Photo by Matthew Beziat. (MBP list)

Southern Ground Cedar in Carroll Co., Maryland (7/7/2018). (c) ShawnT Dash, some rights reserved (CC BY-NC). Photo by ShawnT Dash via iNaturalist. (MBP list)

Southern Ground Cedar in Charles Co., Maryland (7/1/2007). Photo by Bill Hubick. (MBP list)

Southern Ground Cedar in Cecil Co., Maryland (6/25/2014). Photo by Jim Stasz. (MBP list)

Southern Ground Cedar in Charles Co., Maryland (6/7/2020). (c) martharosetta, some rights reserved (CC BY-NC). Photo by martharosetta via iNaturalist. (MBP list)

Southern Ground Cedar in Carroll Co., Maryland (5/23/2018). Photo by Kirsten Johnson. (MBP list)

Southern Ground Cedar in Garrett Co., Maryland (10/29/2020). No rights reserved. Photo by granolapunk via iNaturalist. (MBP list)

Southern Ground Cedar in Prince George's Co., Maryland (7/31/2020). (c) johnbotany, some rights reserved (CC BY-NC). Photo by John Hall. (MBP list)

Southern Ground Cedar in Anne Arundel Co., Maryland (7/30/2010). Photo by Bill Harms. (MBP list)

Southern Ground Cedar in Prince George's Co., Maryland (3/4/2017). Photo by Bill Harms. (MBP list)

Southern Ground Cedar in Worcester Co., Maryland (3/31/2018). Note horizontal stem at surface of the ground. Photo by Bill Hubick. (MBP list)

Southern Ground Cedar in Garrett Co., Maryland (7/13/2014). Photo by Bill Hubick. (MBP list)

Southern Ground Cedar in Montgomery Co., Maryland (3/22/2016). Photo by Jane Hill. (MBP list)

Southern Ground Cedar in Kent Co., Maryland (3/10/2019). Photo by Bill Hubick. (MBP list)

A Southern Ground Cedar in Charles Co., Maryland (9/25/2016). Photo by Kirsten Johnson. (MBP list)

Southern Ground Cedar in Prince George's Co., Maryland (5/2/2020). (c) wilpersm, some rights reserved (CC BY-NC). Photo by wilpersm via iNaturalist. (MBP list)

Southern Ground Cedar in Anne Arundel Co., Maryland (4/21/2021). (c) maddie_b, some rights reserved (CC BY-NC). Photo by maddie_b via iNaturalist. (MBP list)

Southern Ground Cedar in Carroll Co., Maryland (3/3/2020). (c) grimma, some rights reserved (CC BY-NC). Photo by grimma via iNaturalist. (MBP list)

Southern Ground Cedar in Baltimore Co., Maryland (4/24/2020). (c) laurabankey, some rights reserved (CC BY-NC). Photo by laurabankey via iNaturalist. (MBP list)

Southern Ground Cedar in Harford Co., Maryland (1/8/2019). (c) srickey, some rights reserved (CC BY-NC). Photo by srickey via iNaturalist. (MBP list)

Southern Ground Cedar in Garrett Co., Maryland (9/26/2020). (c) johnbotany, some rights reserved (CC BY-NC). Photo by John Hall. (MBP list)

Southern Ground Cedar in Prince George's Co., Maryland (2/19/2020). Photo by Matthew Beziat. (MBP list)


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