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A strobilus (pl.: strobili) is a structure present on many land plant species consisting of sporangia-bearing structures densely aggregated along a stem.Strobili are often called cones, but some botanists restrict the use of the term cone to the woody seed strobili of conifers.
However, unlike these other groups, ovules are produced on cone scales, which are modified shoots rather than sporophylls. Some plants do not produce sporophylls. Sporangia are produced directly on stems. Psilotum has been interpreted as producing sporangia (fused in a synangium) on the terminus of a stem.
Most heterosporous plants there are two kinds of sporangia, termed microsporangia and megasporangia. Sporangia (clustered in sori) on a fern leaf Equisetum arvense strobilus cut open to reveal sporangia. Sporangia can be terminal (on the tips) or lateral (placed along the side) of stems or associated with leaves.
The fertile shoots bear stout, yellowish cones which are only slightly differentiated from the branch. The cones usually bear two kinds of sporangia: lobed megasporangia in the lower part of the cone which produce megaspores and simple microsporangia in the upper part which produce many tiny microspores.
After meiosis, each microspore undergoes mitotic cell division, giving rise to multicellular pollen grains (six nuclei in gymnosperms, three nuclei in flowering plants). Megasporogenesis occurs in megastrobili in conifers (for example a pine cone) and inside the ovule in the flowers of flowering plants. A megasporocyte inside a megasporangium ...
A sorus (pl.: sori) is a cluster of sporangia (structures producing and containing spores) in ferns and fungi. A coenosorus ( pl. : coenosori ) is a compound sorus composed of multiple, fused sori. Etymology
It primarily reproduces by vegetative means, with the majority of shoots arising from rhizomes. Spores are produced in sporangia in blunt-tipped cones at the tips of some stems. [2] [3] The spore cones are yellowish-green, 2,5 cm long. [3]
The plants have intercalary meristems in each segment of the stem and rhizome that grow as the plant gets taller. This contrasts with most seed plants, which grow from an apical meristem - i.e. new growth comes only from growing tips (and widening of stems). Horsetails bear cones (technically strobili, sing. strobilus) at the tips of some stems.