Rhyniophytes †

Morphology

Sporophyte (spore-bearing phase)

Stems / Axes

• Similar to the early polysporangiophytes, such as Aglaophyton, these plants show increasing diversification of axis types. These early plants are constructed with indeterminate and determinate structures like modern plants.

• Determinate aerial stems: above-ground, upright axes (3 mm wide) which terminate in sporangia for dispersal (20 cm tall)

  • Branching is isotomous, anisotomous, and even pseudomonopodial

• Indeterminate rhizomes: ground-running, or below-ground portions, that creep similarly to vegetative propagate the population

  • Vesicular arbuscular mycorrhizae found in the cortex of Rhynia rhizomes

• Adventitious branching: latent "buds" or branches, which could elongate to make new axes, similar to modern plants.

• Vascular tissue present, but not the same as eutracheophytes (see S-type tracheids below)

  • Haplostele with centrarch maturation and S-type tracheids (i.e., annular or helical thickenings made of spongy material)

Diversity

Calyculiphyton blanai † 

• Remy et al., 1991

• Emsian

• Compression fossil with elongate axes that terminate in cup-like structures

• May represent a gametophyte

Celatheca beckii † 

• Hao et al., 1995

• Pragian of Posongchong Formation of eastern Yunnan, China

• Leafless axes dividing anisotomously

• Sterile lateral axes dichotomize two or three times, terminating in recurved tips

• Fertile lateral axes dichotomize to produce a group of four sporangia

• Each sporangium exhibits an outer leaf-like bract which folded around the sporangium

• Celatheca resembles the Australian fossil Yarravia

Eddianna gaspiana †

• Pfeiler & Tomescu, 2018

• Emsian of Gaspe, Canada

• 2mm in diameter with well-developed terete S-type xylem 

Eocooksonia sphaerica †

• Xue et al., 2015

• Originally Cooksonella (Senkevitsch, 1978; Doweld, 2000)

• Upper Silurian (Přídolí) of Xinjiang, Northwest China and Central Kazakhstan

• Pseudomonopodial branching pattern, which forms an apparent main axis with lateral dichotomously branching systems. 

• Specimens demonstrate terminal sporangia with a central body and a border with four to eight elongate-triangular emergences

Hedeia †

• Cookson, 1935

• Early Devonian from Victoria, Australia, Kazakhstan and China

• Erect axes terminating in corymbose clusters of erect sporangia

• This plant resembles the fertile portions of Polythecophyton, and could represent the distal, fertile portions of a larger plant

H. corymbosa

• Cookson, 1935

H. parvula

• Jurina, 1969

H. sinica

• Hao, 1998

Huvenia kleui †

• Hass and Remy, 1991

• Pragian of the Rhenish Massif

• Leafless axes that appear to be flattened and branch dichotomously

• The strand of conducting tissue contains simple tracheids

• The sporangia are borne on the ends of short branching stems (sporangiophores) rather than terminating main stems as in some other early land plants

• The gametophyte of this plant may be Sciadophyton

Rhynia gwynne-vaughanii †

• Kidston & Lang, 1917

• From the Rhynie chert in Aberdeenshire, Scotland

• Rhizomatous plant with upright isotomous and anisotomous axes

  • • Upright axes were up to 3 mm wide and roughly 20 cm tall

    • Axes had a centrarch haplostele

• Sporangia were spindle-shaped (fusiform) and terminal

• Possible deciduous lateral branches were used to disperse laterally over the substrate and stands of the plant and may therefore have been clonal populations

Salopella †

S. australis

• Tims & Chambers, 1984

• Late Silurian (Ludlovian) - Early Devonian (Pragian) of Victoria, Australia

• Axes with at least 2 dichotomies (0.9-2.4 mm wide)

• Plants at least 145 mm tall

• Sporangia 6.5-14.0 mm long and 1.3-2.0 mm wide

S. cf. marcensis

• Edwards et al., 1994

Sporathylacium salopense †

• Edwards, Axe, and Mendez, 2001

• Early Devonian of Wales

• Isolated bivalved sporangia, circular to elliptical in face view, terminating smooth axes.

• Sporangium wall at maturity multilayered.

• Convex valve margins thickened, comprising modified cells and united at the base of a depression.

• Sporangium wall lined internally by a smooth layer (remains of tapetum) with abundant adhering spherical particles (globules).

• Globules also present between and on surfaces of spores.

• Abundant isospores with triradiate apertural folds extending to equatorial crassitude. Spores non-curvaturate.

Yarravia † 

• Lang & Cookson, 1935

• Pragian of Victoria, Australia

• Axes 2 to 2.5 mm in diameter, and up to 7.5 cm in length. 

• No examples of branching or anatomy known 

• The sporangia born radially in groups of 5-6 at the ends of axes.

• Base of sporangia are fused together, but tips may be free; the entire structure can be described as a synangium

Y. oblonga

• • Lang & Cookson, 1935; McSweeny et al., 2021

  • In Y. oblonga, the synangium (the group of fused sporangia) was longer than wide, being about 7 mm long by 1.25 mm wide. The tips of the sporangia were free and appear to consist of tissue not containing spores. 

Y. subsphaerica

• • Lang & Cookson, 1935

  • The synangium of Y. subsphaerica was significantly larger and as long as wide, being about 1 cm in length and width

  • The tips of the sporangia were less prominent

Y. minor 

• • Danzé-Corsin, 1956

Y. gorelovii

• • Ananiev, 1960