Subdivision Lycophytina

This is a clade that includes the clubmosses (lycopsida) and an extinct sister group, the zosterophylls. This group is united by features based on how the xylem matures in the stems, and how the sporangia are arranged on the stems.

Ecology & Form

Sporophyte (spore-bearing) phase



  • Zosterophyllophytes lack leaves, but may exhibit enations

  • Lycopods exhibit lycophylls or microphylls


  • Present in advanced forms

  • Rhizophore (root-like stem) and roots found in lycopods

Reproductive Structures

  • Sporangia are lateral along stem (not terminal as in rhyniophytes or cooksonioids)

    • Kidney-shaped (reniform) in shape

  • Sporangia associated with the adaxial side of a leaf (sporophyll) in lycopods







Geologic Range


  • Includes zosterophylls, the lycopods (living and extinct clubmosses), and possibly the barinophytes

  • Very successful group during the Paleozoic

  • Contemporary diversity: less than 1% of living taxa (i.e. ground pines, quillworts, spike-mosses)

Incertae sedis taxa

Halleophyton zhichangense

  • Li & Edwards 1997

  • Pragian from the Posongchong Formation of eastern Yunnan, China

  • The plant had leafy aerial stems. The leaf bases completely covered the stems forming rhomboidal to hexagonal patterns, except where spore-forming organs or sporangia were present where the leaves thinned out somewhat.

  • The tapered undivided leaves curved inwards and appear to have had a central vein.

  • The sporangia were mixed with leaves and were more-or-less circular in outline, consisting of two valves that split to release the spores.

  • Halleophyton has similarities with Drepanophycus, but a lack of detailed knowledge of some features of that genus persuaded Li and Edwards to create a new genus for their specimens.

  • Although considered to be related to the lycophytes, the exact placement of the genus was left open by its authors. Hao and Xue in 2013 listed the genus as a lycopsid.

Above: Halleophyton zhichangense † (Figs 1-7 from Li & Edwards 1997)

Ornicephalum sichuanense

  • Edwards & Li 2018

  • Early Devonian of Sichuan, China

  • Plant with smooth stems terminating in lax strobili composed of bivalved sporangia inserted helically and supported by long distally curved stalks

  • Sporangia consist of two unequal valves, the smaller being adaxial and separated from the larger abaxial valve by an almost transverse dehiscence line

  • Stalk merges with the outer surface of the abaxial valve such that no junction is visible

Above: Ornicephalum sichuanense (from Plate II of Edwards & Li 2018)

Yanmenia longa

  • Wang 2007; Edwards et al. 2016

  • Early Devonian, Sichuan Province, China

  • Herbaceous leafy stems with distal branching isotomous or lateral in opposite pairs

  • Simple entire persistent leaves with decurrent broad bases and bifacial laminae, almost circular to elliptical in face view. Laminae directed distally

  • Leaves attached to all sides of stem in a low helix, 6 or rarely 8 per gyre.

Above: Yanmenia longa † (Fig 2, Edwards et al. 2016)

Additional Resources

  • Cultivation techniques for clubmosses (Benca 2014)