Horneophytes †

Ecology & Form

• Probably lived in wet, shore environments; grew on sandy, organic-rich soil in damp to wet locations

• Fossils of chytrids, ancient fungi, have been found in the tissue of Horneophyton

Sporophyte (spore-bearing) phase

Horneophyton lignieri †

• Kidston & Lang 1920; Barghoorn & Darrah 1938

Stems

• Upright axes 20 cm tall (2 mm wide) growing from corm-like base

• These plants exhibit equal-branching (isotomous) in distal branches; slightly anisotomous in proximal axes

• Axis tips terminated by sporangia

• Stomata are relatively rare and are enclosed by distinctly modified cells (Hass 1991)

• Lack true vascular tissue but possessed water-conducting cells similar to bryophyte hydroids and sugar-conducting cells similar to leptoids

Roots

• Horneophyton lacks roots but possesses rhizoids emerging from the corm to anchor to the soil

• Evidence of fungal associations (Strullu-Derrien et al., 2014) in the parenchyma of the cortex

  • • Arbuscules from the glomeromycete, Palaeoglomus boullardii †, similar to the living taxon Glomus.

    • Evidence of a mucoromycete, Palaeoendogone gwynne-vaughaniae †, similar in form to the living taxon Endogone. This fungus has thin, branched hyphae populating the plant's corm, forming thicker, coil-like structures between the cells. 

    • In modern plants, these fungi aid in mineral absorption for the plant

Leaves

• Leafless

• It is assumed that the upright stems were photosynthetic, although they may have not been wide enough to support chlorophyllous tissues (see Langiophyton below)

Reproduction

• Spore-bearing plants with sporangia that are stem-like (cylindrical) and the sporangia were forked

• Bumps or emergences are on the sporangia

• Central column of sterile tissue (=columella) found in "horn"

  • Similar (homologous?) to Aglaophyton †, hornworts, and mosses

• Spores were released through a slit at the top of each lobe

  • Spores were trilete meiospores with short conical protuberances

• The chytrid taxon, Rhizophydites matryoshkae †, has been found preserved on the spores of Horneophyton (Krings et al., 2021) as probable parasites