| Azolla nilotica | |
|---|---|
 | |
Scientific classification  | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Division: | Polypodiophyta |
| Class: | Polypodiopsida |
| Order: | Salviniales |
| Family: | Salviniaceae |
| Genus: | Azolla |
| Species: | A. nilotica |
| Binomial name | |
| Azolla nilotica | |
Azolla nilotica is a medium-sized floating fern, that naturally occurs in the Nile and in eastern and central Africa. It is assigned to the family Salviniaceae.
Azolla nilotica is a floating water-bound fern of up to 32 cm (13 in) long, with a long, horizontal, branched, hairy rhizome of up to 2 mm (0.079 in) thick. Side branches are alternately set. The hairy roots spring in bundles from the nodes. Each leaf consists of an elliptic to broadly ovate green upper lobe of up to 2 mm (0.079 in) long, with a rounded or broadly pointed tip, with a nobbly middle and a broad translucent edge. The lower lobe lacks colour, is smaller, thinner and contains a cavity that holds the symbiont cyanophyte, that fixes aerial nitrogen making nitrate available to the plant. Azolla species have two types of spores (a state called heterosporous), small macrospores and minute microspores. The spore forming organs (called sporocarps) grow in the axils of the older leaves. [2] In case of A. nilotica, the sporocarps occur in groups of four, and may consist of any combination of macrosporocarps and groups of microsporocarps (or massulae). [3]
A. nilotica differs from other Azolla species by its larger habit, whereas other species, particularly those of the subgenus Azolla break into cm size fragments. A. nilotica also has its roots in bundles while all other species have single roots. The upper lobe of the leaf is larger than the lower, in contrast to A. filiculoides where the lower leaf is larger in outline. [2] The sporocarps are in groups of four, not in pairs such as in the other species. The plant never attains a red color, such as is often seen towards the end of the growing season in all other Azolla species. [3]
The name A. nilotica was first published by the German botanist Georg Heinrich Mettenius in the book Plantis Tinneanis, that was published in 1865, who credits French botanist Joseph Decaisne for the name. [4]
The species name nilotica refers to the fact that it was collected from the river Nile. [2]
The species can be found in the eastern half of Africa, from southern Sudan, and South-Sudan to the Democratic Republic of Congo, Gabon, Rwanda, Burundi, Uganda, Kenya, Tanzania, Malawi, Mozambique, Zambia, and Zimbabwe. [1] Late Holocene fossil spores have been found in the Nile delta, among Cyperus papyrus . It may have gone extinct with the demise of large areas of papyrus reeds, due to the reclaim of these swamps for agriculture. [5]
Azolla nilotica has a symbiotic relationship with cyanobacteria that fix gaseous nitrogen into nitrate, of a species that has variously been called Anabaena azollae, Nostoc azollae or Trichormus azollae. [7] [6] It occurs in stagnant or slowly streaming water, such as temporary pools, waterholes and lake edges, and can persist on drying mud. It occurs from sea level to an altitude of 1650 m. [8] It is intolerant of temperatures below 10 °C (50 °F), so there is little risk that the species will become naturalised outside of the tropics. [3]
Due to its high nitrate content, the plant is used as green fertilizer, like other Azolla species. [8]
A fern is a member of a group of vascular plants that reproduce via spores and have neither seeds nor flowers. They differ from mosses and other bryophytes by being vascular, i.e., having specialized tissues that conduct water and nutrients and in having life cycles in which the branched sporophyte is the dominant phase. Ferns have complex leaves called megaphylls, that are more complex than the microphylls of clubmosses. Most ferns are leptosporangiate ferns. They produce coiled fiddleheads that uncoil and expand into fronds. The group includes about 10,560 known extant species. Ferns are defined here in the broad sense, being all of the Polypodiopsida, comprising both the leptosporangiate (Polypodiidae) and eusporangiate ferns, the latter group including horsetails or scouring rushes, whisk ferns, marattioid ferns, and ophioglossoid ferns.
Azolla is a genus of seven species of aquatic ferns in the family Salviniaceae. They are extremely reduced in form and specialized, looking nothing like other typical ferns but more resembling duckweed or some mosses. Azolla filiculoides is one of just two fern species for which a reference genome has been published.
The order Salviniales is an order of ferns in the class Polypodiopsida.
The Marsileaceae are a small family of heterosporous aquatic and semi-aquatic ferns, though at first sight they do not physically resemble other ferns. The group is commonly known as the "pepperwort family" or as the "water-clover family" because the leaves of the genus Marsilea superficially resemble the leaves of a four-leaf clover. In all, the family contains 3 genera and 50 to 80 species with most of those belonging to Marsilea.
Salvinia, a genus in the family Salviniaceae, is a floating fern named in honor of Anton Maria Salvini, a 17th-century Italian scientist. Watermoss is a common name for Salvinia. The genus was published in 1754 by Jean-François Séguier, in his description of the plants found round Verona, Plantae Veronenses Twelve species are recognized, at least three of which are believed to be hybrids, in part because their sporangia are found to be empty.
Heterocysts or heterocytes are specialized nitrogen-fixing cells formed during nitrogen starvation by some filamentous cyanobacteria, such as Nostoc punctiforme, Cylindrospermum stagnale, and Anabaena sphaerica. They fix nitrogen from dinitrogen (N2) in the air using the enzyme nitrogenase, in order to provide the cells in the filament with nitrogen for biosynthesis.
Diazotrophs are bacteria and archaea that fix atmospheric nitrogen gas into a more usable form such as ammonia.
Anabaena is a genus of filamentous cyanobacteria that exist as plankton. They are known for nitrogen-fixing abilities, and they form symbiotic relationships with certain plants, such as the mosquito fern. They are one of four genera of cyanobacteria that produce neurotoxins, which are harmful to local wildlife, as well as farm animals and pets. Production of these neurotoxins is assumed to be an input into its symbiotic relationships, protecting the plant from grazing pressure.
Rhizopogon is a genus of ectomycorrhizal Basidiomycetes in the family Rhizopogonaceae. Species form hypogeous sporocarps commonly referred to as "false truffles". The general morphological characters of Rhizopogon sporocarps are a simplex or duplex peridium surrounding a loculate gleba that lacks a columnella. Basidiospores are produced upon basidia that are borne within the fungal hymenium that coats the interior surface of gleba locules. The peridium is often adorned with thick mycelial cords, also known as rhizomorphs, that attach the sporocarp to the surrounding substrate. The scientific name Rhizopogon is Greek for 'root' (Rhiz-) 'beard' (-pogon) and this name was given in reference to the rhizomorphs found on sporocarps of many species.
The wildlife of Egypt is composed of the flora and fauna of this country in northeastern Africa and southwestern Asia, and is substantial and varied. Apart from the fertile Nile Valley, which bisects the country from south to north, the majority of Egypt's landscape is desert, with a few scattered oases. It has long coastlines on the Mediterranean Sea, the Gulf of Suez, the Gulf of Aqaba and the Red Sea. Each geographic region has a diversity of plants and animals each adapted to its own particular habitat.
Pilularia americana, the American pillwort, is an unusual species of fern. The fronds essentially consist of the stems only, any form of flattened laminae having been lost. It is in the aquatic fern family Marsileaceae, and is related to the water clovers and also to Azolla and Salvinia.
Azolla pinnata is a species of fern known by several common names, including mosquitofern, feathered mosquitofern and water velvet. It is native to much of Africa, Asia and parts of Australia. It is an aquatic plant, it is found floating upon the surface of the water. It grows in quiet and slow-moving water bodies, because swift currents and waves break up the plant. At maximum growth rate, it can double its biomass in 1.9 days, with most strains attaining such growth within a week under optimal conditions.
Adiantum viridimontanum, commonly known as Green Mountain maidenhair fern, is a rare fern found only in outcrops of serpentine rock in New England and Eastern Canada. The leaf blade is cut into finger-like segments, themselves once-divided, which are borne on the outer side of a curved, dark, glossy rachis. These finger-like segments are not individual leaves, but parts of a single compound leaf. The "fingers" may be drooping or erect, depending on whether the individual fern grows in shade or sunlight. Spores are borne under false indusia at the edge of the subdivisions of the leaf, a characteristic unique to the genus Adiantum.
Asplenium tutwilerae is a rare epipetric fern found only in Hale County, Alabama, United States. A. tutwilerae is a fertile allotetraploid, formed by the chromosomal doubling of a specimen of the sterile diploid A. × ebenoides, a hybrid of A. platyneuron and A. rhizophyllum. Except for its spores, which are fertile rather than malformed, A. tutwilerae is essentially identical to A. × ebenoides and was described as part of that species until 2007. It is named in honor of Julia Tutwiler, who discovered the only known wild population at Havana Glen in 1873.
Marsilea minuta, or dwarf waterclover is a species of aquatic fern in the family Marsileaceae. It is not to be confused with Marsilea minutaE.Fourn. 1880, which is a synonym for Marsilea vestita. Other common names include gelid waterklawer, small water clover, airy pepperwort, and pepperwort, though the lattermost also applies to plants in the genus Lepidium. In French it is called marsilea à quatre feuilles and petite marsilée, the latter appearing to be a calque with the Latin botanical name. In Chinese it is 南国田字草, literally "southern field word grass," referencing the similarity of the leaflet shape to the Chinese character for "field." The Koch Rajbongshi people and Garo people call it shusni shak. It is called 'শুশনি শাক' in Bengali. In parts of India it can be called sunisanakka In Indonesian it is semanggi, but this name also applies to Marsilea crenata. In Japanese it is nangokudenjiso and in Thai it is phakwaen. In Malaysian it is tapak itek. In the Philippines it is kaya-kayapuan.
Leucospermum saxosum is an upright evergreen shrub of up to 2 m (6.6 ft) high, that is assigned to the family Proteaceae. It has lance-shaped, leathery leaves and egg-shaped flower heads of about 5 cm (2.0 in) in diameter, with initially yellow-orange flowers, later turning crimson, from which long styles stick out, giving the flower head the appearance of a pincushion. It is called escarpment pincushion in English. It grows on quartzite soils in the mountains on the Zimbabwe-Mozambique border and in eastern Transvaal.
Myriopteris allosuroides is a moderately-sized fern of Mexico, a member of the family Pteridaceae. Unlike many members of its genus, its rachides are grooved on the upper surface and largely free of hairs or scales. One of the cheilanthoid ferns, it was usually classified in the genera Cheilanthes or Pellaea until 2013, when the genus Myriopteris was again recognized as separate from Cheilanthes. It typically grows on dry, rocky slopes over acidic, particularly basaltic, rock.
Echinochloa pyramidalis is a species of large grass, occurring naturally in flooded regions and beside lakes in tropical Africa and America, and introduced to various other countries. It is commonly known as antelope grass.
Argyrochosma fendleri, Fendler's false cloak fern, is a fern known from the western United States and northwestern Mexico. It grows in rocky habitats, and is distinguished from other members of the genus by its zig-zag leaf axes. Like many species in the genus, it bears white powder on the underside of its leaves. First described as a species in 1851, it was transferred to the new genus Argyrochosma in 1987, recognizing their distinctness from the "cloak ferns".
Argyrochosma incana, the hairy false cloak fern, is a fern known from the southwestern United States through Mexico to Guatemala, and from a disjunct population in the Dominican Republic. It grows on rocky slopes and steep banks, often in forests. Like many of the false cloak ferns, it bears white powder on the underside of its leaves. First described as a species in 1825, it was transferred to the new genus Argyrochosma in 1987, recognizing their distinctness from the "cloak ferns".
