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In ferns, the sori form a yellowish or brownish mass on the edge or underside of a fertile frond. In some species, they are protected during development by a scale or film of tissue called the indusium ( pl. : indusia ), which forms an umbrella-like cover.
Positive fern test with amniotic fluid as seen under the microscope. The fern test is a medical laboratory test used in obstetrics and gynecology.The name refers to the detection of a characteristic "fern like" pattern of vaginal secretions when a specimen is allowed to dry on a glass slide and is viewed under a low-power microscope.
Prothallus of the tree fern Dicksonia antarctica (note new moss plants for scale) Spore-bearing plants , like all plants, go through a life-cycle of alternation of generations . The fully grown sporophyte , what is commonly referred to as the fern , produces genetically unique spores in the sori by meiosis .
Cyatheaceae are leptosporangiate ferns, the most familiar group of monilophytes. [3] The Cyatheaceae usually have a single, erect or creeping rhizome (stem). Their fronds (leaves) are also very large, although not as large as the tree ferns of the Marattiaceae. Some species have fronds reaching 3–4 m in length, and have a final crown width of ...
Hymenophyllaceae: displaying the thinnest fronds of any fern species, [7] hymen is derived from the Greek word for 'membrane', and phyllon meaning 'leaf'. [5] Another defining feature is the sorus structure, a two-flapped indusium which houses the sporangia in a protective receptacle, often clustered around a central axis. [5]
In ferns, sporangia are typically found on the abaxial surface (underside) of the leaf and are densely aggregated into clusters called sori. Sori may be covered by a structure called an indusium. Some ferns have their sporangia scattered along reduced leaf segments or along (or just in from) the margin of the leaf.
Athyrium (lady-fern) is a genus of about 180 species of terrestrial ferns, with a cosmopolitan distribution. It is placed in the family Athyriaceae , in the order Polypodiales . [ 1 ] [ 2 ] Its genus name is from Greek a- ('without') and Latinized Greek thyreos ('shield'), describing its inconspicuous indusium (sorus' covering). [ 3 ]
Aspidotis densa is a species of fern in the Cheilanthoid subfamily, known by the common name Indian's dream or Serpentine fern or dense lace fern.It is native to the west coast of North America from British Columbia to California and east to the Rocky Mountains in Idaho, Montana, and Wyoming; there is a disjunct population on serpentine soils in Quebec.