Protolepidodendrids † 

Ecology & Form

Stems

• Herbaceous or sub-woody with isotomous and anisotomous branching; 

• Prostrate rhizome was probably indeterminate

Leaves

• Microphylls display a diamond-shaped or rhomboid pattern from the attachment of the leaf bases, similar to the lepidodendrids

• Microphylls are branched, which seems to be contrary to the definition of a microphyll (i.e., single-veined leaf)

  • No other lycophytes display forked leaves

  • The early member, Zhengelia, does not exhibit this trait

• Some leaves have a ligule

Diversity

Archaeosigillaria †

• Vanuxem, 1842; Kidston, 1901

A. conferta

• Menéndez, 1965

• Devonian of Puerto Rico

• Originally named Cyclostigma confertum

A. kidstonii

• Kräusel & Weyland, 1949

• Mississippian of the UK

A. minuta

• Lejal-Nicol, 1970

• Late Devonian of Niger

A. nathorstii

• Kräusel & Weyland, 1949

• Mississippian of Norway

A. picosensis

• Kräusel & Dolianti, 1957

• Early Devonian of Brazil

A. primaeva

• White, 1907

• Middle Devonian of New York State

• Originally called Lepidodendron primaevum

A. serotina

• Kräusel & Weyland, 1949

• Originally called Archaeosigillariopsis serotina

A. sigillarioides

• Lejal-Nicol, 1970

• Late Devonian of Niger

A. subcostata

• Danzé-Corsin, 1965

• Mississippian of Niger

A. vanuxemii 

• • Grierson & Banks, 1963

  • Leaves 5-6 mm long, simple, possibly petiolate, with a deltoid lamina that bears three or four opposite pairs of small serrations and tapers to an acute apex tipped by a tiny hair (Senkewich, 1956; Fairon-Demaret & Banks, 1978).

  • Stems are regarded as characterized by hexagonal patterns produced by subepidermal thick-walled cells that surround the areas of attachment of leaves

Atasudendron mirum † 

• Senkevitsch et al., 1993

• Givetian of Kazakhstan

Barrandeina † 

• Stur, 1882

B. agadirica

• • Senkevitsch, 1961

  • Givetian of Kazakhstan

B. aroostookensis

• • Schopf, 1965

  • Middle Devonian of Maine

B. dusliana

• • Štúr, 1881

  • Givetian of Czech Republic

B. karatauensis

• • Senkevitsch, 1992

  • Eifelian of Kazakhstan

B. kolderupii

• • Kräusel & Weyland, 1934

  • Devonian

  • Originally called Psygmophyllum kolderupii

B. orlovii

• • Jurina, 1982

  • Givetian of Kazakhstan

B. pectinata

• • Høeg, 1931

  • Middle Devonian of Norway

B. perryana

• • White, 1905

  • Middle Devonian (?) of Maine

  • Originally called Anarthrocanna perryana

Barrandeinopsis † 

• Kryshtofovich, 1955

B. antiqua

• • Radczenko, 1962

  • Devonian

  • Originally called Minusia antiqua

B. beliakovii

• • Kryshtofovich, 1955

  • Devonian of Russia

B. kirkinskayae

• • Ananiev, 1962

  • Middle Devonian of Russia

Blasaria sibirica † 

• Zalessky, 1934

• Middle Devonian of Russia

Broeggeria † 

• Nathorst, 1915

• Emsian-Eifelian

B. laxa

• • Ananiev, 1960

  • Emsian of Russia

B. norvegica

• • Nathorst, 1915

  • Eifelian of Norway

B. strobiliformis

• • Dorf, 1933

  • Emsian of Wyoming

Cyclostigma † 

• Haughton, 1859

C. aegypticum

• • Jongmans & Koopmans, 1940

  • Carboniferous of Egypt

C. asiaticum

• • Radczenko, 1957

  • Carboniferous of Russia

C. australe

• • Feistmantel, 1879

  • Carboniferous of Australia

C. brasiliense

• • Dolianiti, 1962

  • Visean of Brazil

C. cambricum

• • Crookall, 1964

  • Kasimovian of UK

C. dasyphyllum

• • Mägdefrau, 1936

  • Carboniferous of Germany

C. distans

• • Chachlov, 1940

  • Carboniferous of Russia

C. goeppertii

• • Doweld, 2017

  • Famennian of Poland

C. majus

• • Kidston, 1964

  • Bashkirian of UK

C. primorskiense

• • Zimina, 1989

  • Famennian of Russia

Eleutherophyllum † 

• Stur, 1877

Gilboaphyton †

• Arnold, 1937

G. argentinum † 

• Carrizo & Azcuy, 2006

• Mississippian of Argentina

G. changyangense †

• Feng, 1984

• Late Devonian of China

G. goldringiae † 

• Arnold, 1937; emended Berry and Edwards, 1996

• Middle Devonian of New York

• Dichotomous branching. 

• Leaves spirally-arranged, their enlarged bases forming broadly fusiform to hexagonal patterns delimited by narrow grooves. 

• Persistent leaves are laminar, divided into a large medial segment and two substantially smaller and shorter distal-pointing opposite lateral segments about midway along the total leaf length. 

• Protostelic xylem column lobate in outline, exarch.

G. griersonii †  

• Berry and Edwards, 1996

• "no younger than Frasnian, and no older than late Eifelian"

• Vegetative stems, 8-14.5 mm diameter, and up to at least 11 cm in length, bifurcating probably isotomously. 

  • Stem surfaces divided into spirally arranged, adjoining, longitudinally elongate hexagonal or fusiform swollen leaf bases; 7-8 bases per horizontal turn, separated by narrow grooves, each bearing a persistent leaf just above its center. 

• Leaves slender, upright, up to 9 mm long and 1.20-1.49mm wide with broad base, divided approximately halfway along their length to give a narrow central segment and two much shorter lateral upwards-pointing segments, all tips acute. 

  • Cortex differentiated into layers, Outer zone of stem tissues most resistant to decay, containing elongate regions of softer tissues seated within the leaf bases connected to a cylinder of similar tissue associated with the leaf trace.

Jurinodendron † 

• Doweld, 2001

• This taxon may be a lepidodendrid

J. aegypticum

J.  australe

J.  brasiliense

J.  brevifolium

J. cambricum

J.  dasyphyllum

J. hercynium

J. macconochiei

J.  majus

J. pacificum

J. primorskiense

J. sigillarioides

J. sinaicum

J. ungeri

J.  ursinum

Knorria † 

• Sternberg, 1825

K.  aciculari-acutifolia

• • Weiss, 1886

  • Late Devonian of Germany

K.  acicularis

• • Göppert, 1846

  • Mississippian of Poland

K. acutifolia

• • Göppert, 1847

  • Mississippian of Poland

K. anceps

• • von Eichwald, 1854

  • Permian of Russia

K.  apicalis

• • von Eichwald, 1854

  • Pennsylvanian of Ukraine

K.  bailyana

• • Schimper, 1870

  • Famennian of Ireland

K.  cancellata

• • von Eichwald, 1854

  • Pennsylvanian of Ukraine

K.  cervicornis

• • Roemer, 1860

  • Carboniferous of Germany

K.  chemungensis

• • Arnold, 1939

  • Devonian of Eastern North America

  • Originally called Sigillaria chemungensis

K.  confluens

• • Göppert, 1850

  • Mississippian of Germany

K.  cylindrica

• • Roemer, 1860

  • Carboniferous of Germany

K.  dichotoma

• • Jukes & Salter, 1856

  • Originally called Sigillaria dichotoma

K.  distans

• • Newberry, 1853

  • Pennsylvanian of Ohio

K.  fusiformis

• • Roemer, 1850

  • Mississippian of Germany

K.  goeppertii

• • Roemer, 1843

  • Mississippian of Germany

K.  hildrethii

• • Newberry, 1853

  • Pennsylvanian of Ohio

K.  imbricata

• • Sternberg, 1825

  • Originally called Lepidolepis imbricata

K.  jugleri

• • Roemer, 1843

  • Mississippian of Germany

K.  longifolia

• • Göppert, 1847

  • Mississippian of Poland

K.  mammillaris

• • von Eichwald, 1854

  • Carboniferous of Russia

K.  mariana

• • Michael, 1895

  • Late Triassic of Poland

K.  megastigma

• • Roemer, 1843

  • Mississippian of Germany

K.  microcostata

• • Zalessky, 1931

  • Famennian of Russia

K.  polyphylla

• • Roemer, 1843

  • Mississippian of Germany

K.  princeps

• • Göppert, 1852

  • Late Triassic of Poland

K.  richteri

• • Geinitz, 1855

  • Pennsylvanian of Germany

K.  schrammiana

• • Göppert, 1847

  • Mississippian of Poland

K.  sellonii

• • Sternberg, 1825

  • Carboniferous of Germany

K.  taxina

• • Lindley & Hutton, 1833

  • Moscovian of the UK

K.  uralica

• • Neuburg, 1961

  • Originally called Knorriopsis uralica

K.  verrucosa

• • Zalessky, 1905

  • Originally called Selaginites verrucosus

Leclercqia † 

• Emsian - Middle Devonian

L. andrewsii †

• Gensel and Kasper, 2005

L. complexa  †

• Banks, Bonamo and Grierson, 1972; Bonamo, Banks and Grierson, 1988

L. uncinata †

• Xu et al., 2011

• Axes branching isotomously or anisotomously at angles of 15–45

  • 1.6–2.6 mm wide, at least 70 mm long

• Leaf bases elongate-fusiform, tightly arranged in helices or pseudowhorls

  • 8-10 leaves inserted on the axis per gyre

  • Leaf consists of a basal segment, dividing just below the midpoint into three major segments, a long narrow central segment, and two further divided opposite lateral segments arranged in three dimensions

  • Deflected abaxially, tapering distally and terminating in an abaxially tightly recurved hook

  • Pairs of lateral major segments are divided near the base into two or very often three more or less equal minor segments

• Sporophyll similar in morphology to sterile leaf; no strobilus formed

  • Sporangium ovate to fusiform in lateral view, ovate in adaxial view, attached by an oval pad proximal to the division of the leaf,

  • Plant homosporous

Lepidosigillaria † 

• Kräusel & Weyland, 1949

Libyaria † 

• Lejal-Nicol, 1975

Minarodendron cathaysiense † 

• Liu et al., 2013

• Givetian of Yunnan, South China

• Possessed small, helically arranged microphylls with a distinctive trifurcate apex, consisting of two lateral tips directed upward and a central tip bent downward.

• Exhibited repeated isotomous dichotomous branching, with some axes dividing as many as seven times.

• Bore scattered fertile leaves (sporophylls) rather than compact cones, with a single sessile sporangium attached to the adaxial side of each sporophyll.

• Had a solid exarch protostele with numerous protoxylem ridges and metaxylem tracheids containing distinctive multiperforate bordered pits ("pitlet sheets"), a feature shared with some later lycopsids.

• Reached a larger size with stems up to 60 mm wide, suggesting a substantial, upright growth form.

• The combination of thick axes, large stem diameter, and extensive cortex suggests that Minarodendron was probably a small tree rather than a herbaceous plant.

• It provides important evidence that arborescent growth may have evolved within the Protolepidodendrales by the late Middle Devonian, earlier than previously appreciated.