CLASS LYGINOPTERIDOPSIDA (=HYDRASPERMAN SEED FERNS)

These plants have a fossil history which ranges from the upper Devonian to the Permian. They have seeds in cupules and synangiate pollen organs. This may be an artificial group.

• ORDER LYGINOPTERIDALES
  • These plants are common in the Carboniferous. They have stems up to 3 cm in diameter which contain pith with vascular bundles. The primary xylem is mesarch. The leaves are up to .5 m long and have dichotomous venation. The seeds are barrel-shaped (about 5mm long) and are surrounded by a single integument. The beak of the nucellus (megasporangium) forms a pollen chamber. The seed occurs in a cupule.
  • Crossotheca, Diplothmema, Elkinsia, Eusphenopteris, Heterangium, Karenopteris, Lagenostoma, Lyginopteris, Mariopteris, Palmatopteris.

CLASS MEDULLOSOPSIDA (=MEDULLOSAN SEED FERNS)

• ORDER MEDULLOSALES
  • These plants are common in the Carboniferous. They have polystelic stems with a trunk up to 5m tall with a spray of fronds at the top. Leaves have sunken stomata. The seeds have an integument of several layers and form a micropyle. The nucellus ids free from the integuments. The pollen-bearing structures occur in a cup. Pollen wall has a single long suture.
  • Alethopteris, Neuralethopteris, Lonchopteris, Lonchopteridium, Cardioneuopteris
  • Laveineopteris, Callipteridium, Margaritopteris
  • Neuropteris, Reticulopteris, Odontopteris, Macroneuropteris, Neurodontopteris, Neurocallipteris, Barthelopteris, Lescuropteris, Palaeoweichselia
  • Dolerotheca, Medullosa, Pachytesta.

CLASS CALLISTOPHYTOPSIDA (=CALLISTOPHYTALEAN SEED FERNS)

• ORDER CALLISTOPHYTALES
  • These plants are found in the Carboniferous and Permian periods. They have stems which are relatively thin (1.8-0.3cm in diameter) with a solid pith. Secondary tissue is well developed. The seeds are small with 3 integument layers (the nucellus is free). Pollen is saccate. One family (Emplectopteridaceae) os also known as the gigantopterids, which are highly advanced plants of the late Permian and may have persisted into the lower Triassic. The vascular tissue of gigsantopterids contained vessels and the mature leaves had net veins; their strobili resembled those of cycadedoids.
  • Pseudomariopteris
  • Angarocarpus, Callandrium, Callistophyton, Callospermarion, Diksonites, Eremopteris, Gondwanotheca, Idanothekion, Paragondwanidium.
  • Emplectopteris, Gigantonoclea, Jiaochengia

CLASS PELTASPERMOPSIDA (=PELTASPERMALEAN SEED FERNS)

• ORDER CORYSTOSPERMALES
  • These plants occur in the Triassic. They have small fern-like leaves. The pollen is saccate; the pollen organs resemble those of Lyginopteris.
  • Dicroidium, Doylea, Pterusuchus, Umkomasia.

• ORDER PELTASPERMALES
  • These plants occur in the Permian and Triassic. Seeds occur on the lower surface of an umbrella-like organ.
  • Antevsia, Callipteris, Lepidopteris, Peltaspermum.

CLASS CAYTONIOPSIDA (=HIGHER SEED FERNS)

These plants occur in the Mesozoic and have recurved cupules in which the seeds occur.

• ORDER CAYTONIALES
  • These plants occur in the Triassic to the Cretaceous. Seeds occur in circular sacs with slits. Pollen is small and is winged with 2 bladders.
  • Caytonanthus, Caytonia, Sagenopteris.

• ORDER GLOSSOPTERIDALES (=ARBERIALES)
  • These plants occur from the Permian to the Triassic. They have a cluster of seeds attached to a common receptacle in the axil of certain leaves. This group also includes the gigantopterids
  • Glossopteridaceae: Glossopteris, Scopus
  • Gigantopteridaceae: Cathaysiopteris, Cathaysiopteridium, Gigantoclea, Gigantopteris, Gothanopteris, Gigantopteridium, Palaeogoniopteris, Zeilleropteris, Delnortea, Emplectopteridium, Emplectopteris, Neogigantopteridium, Vasovinea.