Zosterophyll

A zosterophyll is an extinct vascular plant of the zosterophyll lineage, an early group of land plants closely related to the ancestors of lycophytes. Its branching axes bore lateral sporangia rather than terminal ones.

Vascular plant: A plant with specialized tissues that transport water, minerals, and sugars through its body. Zosterophylls were among the early land plants with vascular tissues.
Sporangium dehiscence: The opening of a spore-producing structure to release its spores. Zosterophyll sporangia split open to disperse spores.
Silurian: A geologic period from about 443 to 419 million years ago. Zosterophylls appeared during the Silurian expansion of vascular land plants.
Zosterophyllum: An extinct genus of early vascular plants that gives the zosterophyll lineage its name. Its fossils display the lateral, kidney-shaped sporangia characteristic of the group.
Xylem: Plant tissue that conducts water and minerals and helps support the plant body. Its water-conducting tissue let zosterophyll axes grow upright on land.
Homosporous life cycle: A reproductive pattern in which a plant produces one type of spore. Known zosterophylls produced spores of one size class.
Devonian: A geologic period from about 419 to 359 million years ago, marked by major diversification of land plants. Zosterophyll diversity and fossils are especially prominent in Devonian deposits.
Gosslingia: An extinct genus of early vascular plants known from Devonian rocks. Its branching axes and lateral sporangia illustrate zosterophyll architecture.
Sporangium: A structure in which spores are produced and released. Zosterophyll sporangia were borne laterally along their axes.
Sporophyte: The spore-producing multicellular generation in a plant life cycle. The preserved zosterophyll plant body was its sporophyte generation.

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MicrophyllBroader topic: Their leafless axes help frame hypotheses about the origin of lycophyte microphylls.