CLASS CORDAITOPSIDA+

These plants are extinct and are dominants in the Carboniferous period. Very large trees (up to 20m), their upper branches have long, strap-like leaves. The stems have chambered pith and endarch xylem. Although they have a well developed cambium (text with tooltip) A cambium is a zone of meristematic tissue which produces lateral growth in a plant axis. A vascular cambium produces xylem and phloem, a cork cambium occurs in the cortex and produces cork as a covering of older woody stems. , they have no growth rings. The leaves are thin, strap-like and long (more than a meter), with sparse dichotomous venation making them appear to have parallel veins. Both staminate and ovulate cones are compound.

• ORDER CORDAITALES.
  • Amyelon, Cardiocarpus, Cordaianthus, Cordaites, Premnoxylon

CLASS VOLTZIOPSIDA+

These plants are extinct with a fossil history which ranges from the Carboniferous to the Triassic. They are trees with whorls of branches. The leaves are dimorphic; flattened and broad on the large branches and needle-like on the ultimate leafy branches. They have extensive secondary xylem with cones on the ends of branches. The ovulate cones are compound while the staminate cones are simple.

• ORDER VOLTZIALES.
  • Lebachia

CLASS PINOPSIDA

These plants are extant and have a fossil history which dates from the Triassic. Trees; leaves needle-like spiraled or in whorls; 2 microsporangia on the adaxial surface of the microsporophylls; pollen sacccate; ovulate cones compound with ovules directed to center axis; seeds with terminal wing.

They are trees, rarely shrubs. Usually, the leaves are dimorphic. They have extensive secondary xylem. The ovulate cones are compound and the staminate cones are simple.

• ORDER PINALES.
  • Family Pinaceae: Abies, Cedrus, Larix, Pinus, Pseudolarix, Pseudotsuga, Tsuga, Picea

CLASS CUPRESSOPSIDA

These plants are extant and have a fossil history which dates from the Triassic. They range from trees to shrubs; leaves range from scale-like to strap-like to needle-like; often the leaves are dimorphic on the same plant; microsporangia 2-20 on abaxial surface of microsporophyll of ovulate strobilus; pollen with 0-3 saccae; ovules 1-2 per scale and oriented away from axis of strobilus, often cone or aril fleshy.

• ORDER SCIADOPITYALES
  • Family Sciadopityaceae: Sciadopitys

• ORDER ARAUCARIALES
  • Family Araucariaceae: Agathis, Araucaria, Aucarioxylon+
  • Family Podocarpaceae: Podocarpus

• ORDER CUPRESSALES
  • Family Taxodiaceae:
  • Family Cupressaceae: Callitris, Chamaecyparis, Cupressus, Juniperus, Thuja, Cryptomeria, Cunninghamia, Metasequoia, , Sequoia, Sequoiadendron, Taxodium
  • Family Cephalotaxaceae: Cephalotaxus
  • Family Taxaceae: Taxus