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Isoëtes, also written Isoetes and commonly known as the quillworts, is the genus of plants in the class Isoetopsida The Isoetopsida is a class of the Lycopodiophyta. All living plants belong to the genus Selaginella in the Selaginellales or to Isoetes in the order Isoetales. In the past, members of this group have sometimes been placed in the class Isoetopsida, sometimes in the Selaginellopsida or Lycopodiopsida. There are about 700 species of Selaginella and 14 and order Isoetales. The order Isoetales is sometimes placed in the class Isoetopsida, sometimes in the Selaginellopsida or Lycopsida. They are considered "fern allies Fern ally is a general term covering a somewhat diverse group of vascular plants that are not flowering plants and not true ferns. Like ferns, these plants disperse by shedding spores to initiate an alternation of generations". There are about 140-150 species, with a cosmopolitan distribution In biogeography, cosmopolitan distribution is a state of being found almost anywhere around the world. A cosmopolitan biological category, e.g. genus, may be called a cosmopolite but often scarce to rare. Some botanists Botany, plant science, phytology, or plant biology is a branch of biology and is the scientific study of plant life and development. Botany covers a wide range of scientific disciplines that study plants, algae, and fungi including: structure, growth, reproduction, metabolism, development, diseases, chemical properties, and evolutionary split the genus, separating two South American species into the genus Stylites.
Quillworts are mostly aquatic or semi-aquatic in clear ponds and slow-moving streams, though several (e.g. I. histrix, I. nuttallii) grow on wet ground that dries out in the summer. Quillwort leaves In botany, a leaf is an above-ground plant organ specialized for photosynthesis. For this purpose, a leaf is typically flat and thin. There is continued debate about whether the flatness of leaves evolved to expose the chloroplasts to more light or to increase the absorption of carbon dioxide. In either case, the adaption was made at the expense are hollow and quill-like, arising from a central corm A corm is a short, vertical, swollen underground plant stem that serves as a storage organ used by some plants to survive winter or other adverse conditions such as summer drought and heat . A corm consists of one or more internodes with at least one growing point, with protective leaves modified into skins or tunics. The thin tunic leaves are dry. Each leaf is narrow, 2-20 cm long (exceptionally up to 100 cm) and 0.5-3 mm wide; they can be either evergreen In botany, an evergreen plant is a plant having leaves all year round. This contrasts with deciduous plants, which completely lose their foliage for part of the year, winter deciduous Deciduous means falling off at maturity or tending to fall off and is typically used in reference to trees or shrubs that lose their leaves seasonally and to the shedding of other plant structures such as petals after flowering or fruit when ripe. In a more specific sense deciduous means the dropping of a part that is no longer needed, or falling, or dry-season deciduous. They broaden to a swollen base up to 5 mm wide where they attach in clusters to a bulb-like, underground rhizome In botany, a rhizome is a characteristically horizontal stem of a plant that is usually found underground, often sending out roots and shoots from its nodes. Rhizomes may also be referred to as creeping rootstalks, or rootstocks characteristic of most quillwort species, though a few (e.g. I. tegetiformans) form spreading mats. This swollen base also contains male and female sproangia, protected by a thin, transparent covering (velum The term, velum, derived from Latin velum, meaning a "sail", "curtain," "awning" or "veil", has several quite separate meanings in biology:), which is used diagnostically to help identify quillwort species. They are heterosporous In biology, a spore is a reproductive structure that is adapted for dispersal and surviving for extended periods of time in unfavorable conditions. Spores form part of the life cycles of many bacteria, plants, algae, fungi and some protozoans. A chief difference between spores and seeds as dispersal units is that spores have very little stored. Quillwort species are very difficult to distinguish by general appearance. The best way to identify them is by examining the megaspores under a microscope.
- Selected species
- Isoetes alpina New Zealand Quillwort
- Isoetes andicola (syn. In scientific nomenclature, synonyms are different scientific names used for a single taxon. Usage and terminology are different for zoology and botany Stylites andicola)
- Isoetes appalachiana Isoetes appalachiana, commonly known as the Appalachian quillwort , is an aquatic pteridophyte that is widely distributed in the eastern United States. It is most frequently encountered at low to middle elevations of the Appalachian Mountains in Pennsylvania, though its range extends from there south to Florida and Alabama along the eastern slopes Appalachian Quillwort
- Isoetes bolanderi Isoetes bolanderi is a species of quillwort, a type of lycopod. Its common name is Bolander's quillwort. This is a "primitive" aquatic plant native to western North America which grows almost entirely underwater in lakes and other water bodies. It grows from a corm-like stem which remains buried in the mud, producing pointed, cylindrical Bolander's Quillwort
- Isoetes brochonii Pyreneean Quillwort
- Isoetes durieui Durieu's Quillwort
- Isoetes echinospora Spring Quillwort
- Isoetes engelmannii Engelmann's Quillwort
- Isoetes flaccida Southern Quillwort
- Isoetes gemmifera (syn. Stylites gemmifera)
- Isoetes histrix Land Quillwort
- Isoetes howellii Howell's Quillwort
- Isoetes lacustris Lake Quillwort
- Isoetes louisianensis Louisiana Quillwort
- Isoetes melanospora Black-spored Quillwort
- Isoetes nuttallii Nuttall's Quillwort
- Isoetes tegetiformans Mat-forming Quillwort
- Isoetes tenella Spiny Spore Quillwort
- Isoetes tenuissima French Quillwort
- Isoetes valida Strong Quillwort
Many species, such as the Louisiana Quillwort and the Mat-forming Quillwort, are Endangered species An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters. Also it could mean that due to deforestation there may be a lack of food and/or water. The International Union for Conservation of Nature has calculated the. Several species of Isoetes are commonly called Merlin's grass, especially I. lacustris, but also the endagered species I. tegetiformans and I. virginica.
Quillworts are considered by some to be the last remnant of the fossil Fossils are the preserved remains or traces of animals, plants, and other organisms from the remote past. The totality of fossils, both discovered and undiscovered, and their placement in fossiliferous (fossil-containing) rock formations and sedimentary layers (strata) is known as the fossil record. The study of fossils across geological time, how tree Lepidodendron Lepidodendron is an extinct genus of primitive, vascular, arborescent (tree-like) plant related to the Lycopsids (club mosses). It was part of the coal forest flora. They sometimes reached heights of over 30 metres (100 ft), and the trunks were often over 1 m (3.3 ft) in diameter, and thrived during the Carboniferous period. Sometimes called " with which they share some unusual features including the development of both wood and bark, a modified shoot system acting as roots, bipolar growth, and an upright stance.
External links
- Species list (143 species)
- Flora of North America - Isoetes
- wikiPlants - Quillworts
Categories: Lycopodiophyta | Isoetes
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