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Ferns, which may produce sporophylls that are similar to sterile fronds or that appear very different from sterile fronds. These may be non-photosynthetic and lack typical pinnae, e.g. Onoclea sensibilis. Cycads produce strobili, both pollen-producing and seed-producing, that are composed of sporophylls.
Microsporangia occur in all vascular plants that have heterosporic life cycles, such as seed plants, spike mosses and the aquatic fern genus Azolla. In gymnosperms and angiosperm anthers , the microsporangia produce microsporocytes, the microspore mother cells , which then produce four microspores through the process of meiosis .
The Dicroidium plant (which bore Dicroidium leaves, Umkomasia seed bearing structures and Pteruchus pollen organs) is thought to have grown as large trees, with trunks at least 10 metres (33 ft) tall and over 50 centimetres (20 in) wide. [7] Some other possible corystosperms like Pachypteris may have grown as shrubs. [8]
Pteridospermatophyta, also called "pteridosperms" or "seed ferns" are a polyphyletic [1] grouping of extinct seed-producing plants. The earliest fossil evidence for plants of this type are the lyginopterids of late Devonian age. [ 2 ]
Modern heterosporous plants such as many ferns exhibit endospory, in which a megagametophyte is fertilized by a microgametophyte all while still inside the spore wall, gaining nutrients from the inside of spore. [6] Both heterospory and endospory seem to be one of the many precursors to seed plants and the ovary.
The microspore has three different types of wall layers. The outer layer is called the perispore, the next is the exospore, and the inner layer is the endospore.The perispore is the thickest of the three layers while the exospore and endospore are relatively equal in width.
The Osmundastrum cinnamomeum fern forms huge clonal colonies in swampy areas. These ferns form massive rootstocks with densely matted, wiry roots. This root mass is an excellent substrate for many epiphytal plants. They are often harvested as osmunda fiber and used horticulturally, especially in propagating and growing orchids. Cinnamon Ferns ...
The Lyginopteridales are an extinct group of seed plants known from the Paleozoic.They were the first plant fossils to be described as pteridosperms (a polyphyletic group sometimes referred to as "seed ferns") and, thus, the group on which the concept of pteridosperms was first developed; [2] they are the stratigraphically oldest-known pteridosperms, occurring first in late Devonian strata; [3 ...