Diphasiastrum species

Ground Cedars

Ground Cedar
Photo © 1998 by Earl J.S. Rook

Flora, fauna, earth, and sky...
The natural history of the northwoods

Name:

• Diphasiastrum, from the generic name Diphasium, and astrum, "inferiority or partial resemblance", hence, "false Diphasium"
• Ground Cedar, from the resemblance of its scale-like leaves to those of the Cedars
• Other common names include Ground Pine, Clubmoss

Taxonomy:

• Kingdom Plantae, the Plants
• Division Lycopodiophyta, the Clubmosses
  • Class Lycopodiopsida, the Clubmosses
    • Order Lycopodiales, the Clubmosses
      • Family Lycopodiaceae, the Clubmosses
        • Genus Diphasiastrum, the Ground Cedars
• Also known as Lycopodium, Diphasium
• North Country Species
  • complanatum, Ground Cedar
  • digitatum, Fan Clubmoss
  • tristachyum, Blue Ground Cedar
• Five species and six fertile hybrids occur in North America.

Description:

• A creeping, evergreen, rhizomatous clubmoss, with occasional erect branches topped with slim cones.
• Vertical stems multi-branched with scale-like leaves
• Horizontal stems at or below surface of ground.
• Cones cylindrical, ½"-2½", in upright candelabra-like clusters

Identification:

• Club Moss Identification for Amateurs

  1. Our North Country clubmosses are divided into four genera, based upon their leaves and cones.
     • Clubmosses with flat, scale-like leaves belong to this genus, Diphasiastrum, the so-called Ground Cedars, represented by three species in the North Country. All other clubmosses in our area have pointed leaves and a bristly appearance.
  • Clubmosses without cones belong to the genus Huperzia, represented by four species in the North Country, only two at all common.
  • A clubmoss with a cone which is merely a somewhat broader extension of the shoot belongs to the genus Lycopodiella, represented by a single species in the North Country.
  • Clubmosses with distinct cones and bristly leaves belong to the genus Lycopodium, the so-called Ground Pines, represented by six species in the North Country.
  2. If you have a Diphasiastrum, look closely at the ultimate branchlets. If they are cord-like, and nearly square in cross section, then you have Blue Ground Cedar (Diphasiastrum tristachyum). Confirm by:
  • bluish color (hence the common name)
  • leaves on the underside of the branchlet more or less the same size as those on the top and sides
  3. If the ultimate branchlets are narrowly blade-like and flat in cross section, usually green; underside leaves much smaller than lateral and upperside leaves, look at the overall pattern of the branchlets.
• If the branchlets are irregular and almost shaggy in form, you have the common Ground Cedar (Diphasiastrum complanatum). Confirm by:
  • conspicuous annual bud constrictions
  • cone stalks, if present, regularly forked
  • cones mostly ½"-1", lacking sterile tips
• If the branchlets are very regularly fan-shaped, you have Fan Clubmoss (Diphasiastrum digitatum). Confirm by:
  • absence of conspicuous annual bud constrictions
  • cone stalks mostly branching abruptly at base
  • cones mostly ¾"-1½", many with sterile tips

Distribution:

• Circumboreal, mainly north temperate and subarctic.

Habitat:

Fire:

Associates:

History:

Uses:

Reproduction:

• Clonal, reproducing primarily by sprouting from rhizomes.

Propagation:

• Very difficult.

Cultivation:

• Clubmosses can make attractive ground covers, but they do not transplant well.

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