Glossopteris (etymology: from Ancient Greek γλῶσσα (glôssa, " tongue ") + πτερίς (pterís, " fern ")) is the largest and best-known genus of the extinct Permian order of seed plants known as Glossopteridales (also known as Arberiales, Ottokariales, or Dictyopteridiales).

Glossopteris fossils were critical in recognizing former connections between the various fragments of Gondwana: South America, Africa, India, Australia, New Zealand, and Antarctica.

It is unclear whether glossopterids were monoecious or dioecious, the fact that only pollen organ bearing leaves and not ovules were found in some layers suggest that at least some species were the latter.

However, in recent years a few disparate localities in Morocco, Oman, Anatolia, the western part of the island of New Guinea, Thailand and Laos have yielded fossils that are of possible glossopterid affinity.

[21] These peri-gondwanan records commonly occur together with Cathaysian or Euramerican plant species—the assemblages representing a zone of mixing between the strongly provincial floras of the Permian.

[26] However, this category of pollen is known to have been produced by various seed plants, and Triassic examples, in the absence of convincing co-preserved Glossopteris leaves, probably belonged to non-glossopterid groups, such as voltzialean conifers.

Although most modern palaeobotany textbooks cite the continuation of glossopterids into later parts of the Triassic and, in some cases into the Jurassic, these ranges are erroneous and are based on misidentification of morphologically similar leaves such as Gontriglossa,[33] Sagenopteris, or Mexiglossa.

However, based on analogies with modern high-latitude plants, polar-latitude Glossopteris trees have been suggested to have had a tapered, conical profile like that of a Christmas tree and to have been relatively widely spaced to take advantage of the low-angle sunlight at high latitudes,[3] instead of needles, they had large, broad lance- or tongue-shaped leaves commonly with well differentiated palisade and spongy mesophyll layers.

Glossopteris trees are assumed to have been deciduous, as fossil leaves are commonly found as dense accumulations representing autumnal leaf banks.

Seeds borne by Glossopteris bearing plants include the genera Plectilospermum, Choanostoma, Pachtestopsis, Illawarraspermum, Lakkosia, Lonchiphyllum and Homevaleia.

However, more recent studies of the more morphologically diverse fertile organs have shown that taxa had more restricted regional distributions and several intra-gondwanan floristic provinces are recognizable.