Pseudosporochnales †

Diversity

Calamophyton †

• Kräusel & Weyland 1929

• Middel Devonian 

C. primaevum †

• Originally described from the Middle Devonian of Germany

• 35 cm long plant reconstructed with finger-like branched main axis

• The short, dichotomously branched axes bear a single at each end of the sporangium

• In cross-section, stems exhibit a variable number of xylem lobes, ranging from 10 to 33

  • In the distal parts of the plant, there were fewer xylem lobes

  • The xylem strands are extended radially in the cross section

• Ground tissue of stem exhibits fiber bundles

C. bicephalum †

• Leclercq and Andrews 1960

• Middle Devonian 

• Central axis with finger-like arranged side branches with a diameter of about 1 cm and branch dichotomously

• In cross-section, the axis having 14 to 16 xylem segments, which are either oval or have 4-5 radial arms

  • There are only primary xylem

• The "leaves" are three-dimensional structures, each divided dichotomously once horizontally and once vertically

• Young leaves in the distal region of the plant bifurcate only once; axes in the lower area divide up to four times

• There are indications that leaves and sporangia have been on different axes

• The fertile axes are inserted in a pseudowhorl arrangement; sometimes fertile axes are interspersed between sterile whorls

Eospermatopteris †

• Goldring, 1924; Stein et al. 2007

• Givetian of New York, Belgium, Germany

• Large bulbous trunk casts; most do not preserve the aerial portions, but indicate a tree-sized plant for this time

• Carbonaceous strands in the trunk represent poorly preserved vascular strands that exhibit complex anastomoses

E. eriana †

• Goldring 1924; Boyer, 1995; Stein et al. 2007

• Givetian of Gilboa, NY

• Oldest known "tree" on Earth known from the Schoharie Reservoir in New York State

• Aerial portions most probably Wattieza (see below)

E. textilis †

• Goldring 1924; Boyer, 1995

• Combined with E. eriana (Boyer, 1995)

Pseudosporochnus †

• Potonié & Bernard, 1903

• Middle-Late Devonian (Frasnian)

• Small tree (2-4 meters tall) with a bulbous base

• Lateral axes dichotomized several times dichotomous

• The terminal branches are three-dimensional

• Sterile and fertile units are similar, with the latter possessing paired ellipsoidal sporangia

P. hueberi 

• • Stein and Hueber, 1989

  • Originally named Cladoxylon hueberi

  • 40-50 xylem strands in the main axis and 20-25 in the lateral axes

  • Only primary xylem is present and metaxylem tracheids possess uni- to multiseriate bordered pits

P. nodosus 

• • Leclercq and Banks, 1962

  • Second-order branches dichotomized with the lateral branching system giving rise to ultimate branching units that are three-dimensional

  • Fertile branching units possess sessile, ellipsoidal sporangia

  • Circular–elongate structures distributed on all parts representing nests of cortical fibers

Xenocladia medullosina †

• Arnold, 1940

• Middle (Givetian) to Late Devonian (Frasnian)

• Liana growth form was proposed

• Stems have a diameter of about 10 cm and possess secondary xylem

Xinicaulis lignescens †

• Xu et al., 2017

• Late Devonian (Frasnian) of NW China: Bulongguoer Reservoir

• Branch vascular supplies are made up of several traces originating from several xylem ribs

• Trunk expansion is associated with a cylindrical zone of diffuse secondary growth within ground and cortical parenchyma and with production of a large amount of wood containing both rays and growth increments concentrically around individual xylem strands by normal cambia

• The xylem system accommodates expansion by tearing of individual strand interconnections during secondary development

• This mode of growth seems indeterminate, capable of producing trees of large size and, despite some unique features, invites comparison with secondary development in some living monocots