Non-flowering plants comprise plant species that reproduce without flowers, either through spores or seed-producing cones. They include mosses, liverworts, ferns, horsetails, conifers and cycads. This is in stark contrast to the flowering plants, angiosperms, that develop seeds from pronounced flower structures that usually include petals.
Three species of conifer, or cone-producing trees top the list for size in this group of non-flowering plants. In terms of biomass or volume, the giant sequoia (Sequoiadendron giganteum) is also among the oldest living plants. At maturity, this species carries these potential dimensions: 295 to 312 feet in height and a stem volume of 1473.4 cubic meters. Also worth mentioning is the coast redwood (Sequoia sempervirens) that although doesn't grow as massively, does grow even taller: 360 to 394 feet. The largest native conifer of the Southern Hemisphere is the kauri (Agathis australis), maxing out at 131 feet in height.
The largest fern species in the world is a tree-fern native to New Zealand, southeastern-most Australia and some nearby southwestern Pacific Islands. The black tree fern (Cyathea medullaris), grows 49 to 65 feet tall as measured by its trunk-like caudex. Its fronds grow as long as 26 feet.
Cycads, which look like palms, produce seeded cones. The largest cycad species is the Australian species Lepidozamia hopei, which grows very slowly, to a height of 65 feet. The largest cycad native to the New World is the gum palm (Dioon spinulosum), reaching a maximum stem height of 49 feet.