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A sorus (pl.: sori) is a cluster of sporangia ... The shape, arrangement, and location of the sori are often valuable clues in the identification of fern taxa. Sori ...
The genus Phlebodium is exemplified by containing rows of areoles that lack included veins, and each sorus served by two different veins. Correll and Correll, two authors responsible for thirty years of classification since Flora was introduced in 1982, documented Phlebodium aureum as Polypodium aureum as recently as 1982.
Adiantum (/ ˌ æ d i ˈ æ n t əm /), [1] the maidenhair fern (not to be confused with the similar-looking maidenhair spleenwort fern), is a genus of about 250 species of ferns in the subfamily Vittarioideae of the family Pteridaceae, [2] though some researchers place it in its own family, Adiantaceae.
During the early and mid 1900's [7] all thelypterioid ferns were included in the genus Dryopteris because of the sorus shape. However, there are a great many differences between the groups, and these plants are now segregated in their own family. [2] [3] Genetic evidence shows that the family is clearly monophyletic. [3]
In autumn, the warts rot and disintegrate, releasing new thick-walled resting spores of the fungus into the soil. The diploid resting spores (pro-sori) undergo a dormancy period and before germination (probably) a meiotic division and several mitotic divisions, becoming a sorus.
Associated with each sorus in many species is a membranous protective structure called an indusium, which is an outgrowth of the blade surface that may partly cover the sporangia. Some fern species feature frond dimorphism , in which fertile and sterile fronds differ in appearance and structure.
Adiantum viridimontanum is a medium-sized, deciduous, terrestrial fern, [2] about 2 feet (60 cm) wide and 1 to 2 feet (30 to 60 cm) high. [3] Its fronds range from 30 to 75 cm (12 to 30 in) in length from the base of the leaf stalk to the tip.
Within the sori, sporangia mature starting at the apex of the sorus and progressing to the base. They have a continuous, oblique annulus and release round, green trilete spores. The spores grow into thread- or ribbon-like gametophytes ; in many species, the gametophyte has an extended, independent lifespan and can reproduce asexually by ...