Aglaophyton major

Reconstruction of the sporophyte of Aglaophyton major, with a cross section of its sporangium and spores（圖片來源：Falconaumanni，採用 CC BY-SA 3.0 授權）

Age

Devonian（Pragian）

410 Ma

---

Taxonomy

Kingdom: Plantae

Genus: Aglaophyton

Species: Aglaophyton major

---

Morphological description

Aglaophyton major possessed a sporophyte axis with a circular cross-section, smooth and lacking surface ornamentation, reaching up to approximately 6 mm in diameter. The axes exhibited dichotomous branching, with terminal sporangia borne at the tips. These sporangia opened along a spiral dehiscence line upon maturation, releasing numerous homosporous spores. The spores displayed characteristic trilete marks on their surface.

Internally, the axes contained water-conducting tissues resembling those of bryophytes rather than true vascular tissues. The plant lacked true roots, instead forming symbiotic associations with fungi that functioned in water and nutrient uptake. Growth was primarily creeping along the substrate, with only some portions extending upward, reaching an estimated height of about 15 cm.

The gametophyte consisted of a fleshy thallus, rhizoids, gametangiophores, and gametangia. Rhizoids extended downward from the base of the thallus to anchor it within the substrate. One or more gametangiophores arose from the upper surface of the thallus, bearing multiple gametangia. Both the thallus and gametangiophores possessed stomata-like structures. The gametophytes were unisexual, with no evidence of hermaphroditism.

---

Etymology

The genus name Aglaophyton is derived from the Ancient Greek aglaos meaning "splendid" or "beautiful" and phyton meaning "plant".

The species name major is Latin for "larger".

---

Biological description

Aglaophyton major was originally described in 1920 as a species of Rhynia, a genus traditionally considered a vascular plant. However, a 1986 study demonstrated that Aglaophyton lacked true vascular tissue and should instead be classified among non-vascular plants, leading to the establishment of a new genus. Phylogenetic analyses indicate that Aglaophyton major represents a polysporangiophyte closely related to vascular plants, forming a sister group with them, while this combined clade is in turn sister to Horneophytopsida.

Fossil specimen of Aglaophyton major（圖片來源：Jonathan Chen，採用 CC BY-SA 4.0 授權）

Its fossils were discovered near the village of Rhynie in Aberdeenshire, Scotland, in deposits associated with silica-rich hot spring environments. Due to its pivotal evolutionary position, Aglaophyton major is considered to approximate the ancestral morphology of early vascular plants. It is also the earliest known plant to exhibit a symbiotic mycorrhizal relationship with fungi.

(Author: Bai Leng)

---

References

1. Edwards, D. S. (1986). Aglaophyton major, a non-vascular land-plant from the Devonian Rhynie Chert, Botanical Journal of the Linnean Society.

2. Kidston, R., Lang, W.H. (1920). On Old Red Sandstone plants showing structure, from the Rhynie Chert Bed, Aberdeenshire. Part II. Additional notes on Rhynia gwynne-vaughani, Kidston and Lang; with descriptions of Rhynia major, n.sp. and Hornea lignieri, n.g., n.sp., Transactions of the Royal Society of Edinburgh.

3. Remy W., Taylor TN., Hass H., Kerp H. (1994). 4 hundred million year old vesicular-arbuscular mycorrhizae. Proceedings of the National Academy of Sciences of the United States of America.

4. Remy, W., Remy, R. (1980) Lyonophyton rhyniensis n.gen. et nov. spec., ein Gametophyt aus dem Chert von Rhynie (Unterdevon, Schottland). Argumenta Palaeobotanica.

+57.33250, -2.83444

---