Isoetes: Difference between revisions
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{{italic title}}{{Taxobox |
{{italic title}}{{Taxobox |
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| name = '' |
| name = ''Isoëtes'' |
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| image = Illustration Isoetes lacustris0.jpg |
| image = Illustration Isoetes lacustris0.jpg |
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|image caption='' |
|image caption=''Isoëtes lacustris''<ref>illustration from Otto Wilhelm Thomé Flora von Deutschland, Österreich und der Schweiz 1885, Gera, Germany</ref> |
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| regnum = [[Plant]]ae |
| regnum = [[Plant]]ae |
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| divisio = [[Lycopodiophyta]] |
| divisio = [[Lycopodiophyta]] |
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| classis = [[ |
| classis = [[Isoëtopsida]] |
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| ordo = [ |
| ordo = [Isoëtales]] |
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| familia = |
| familia = Isoëtaceae |
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| familia_authority = [[Ludwig Reichenbach|Rchb.]]<ref>{{cite book | last=Reichenbach | first=H. G. L. | year=1828 | title=Conspectus Regni Vegetabilis | page=43 }}</ref> |
| familia_authority = [[Ludwig Reichenbach|Rchb.]]<ref>{{cite book | last=Reichenbach | first=H. G. L. | year=1828 | title=Conspectus Regni Vegetabilis | page=43 }}</ref> |
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| genus = ''''' |
| genus = '''''Isoëtes''''' |
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| genus_authority = [[Carl Linnaeus|L.]] |
| genus_authority = [[Carl Linnaeus|L.]] |
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}} |
}} |
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''''' |
'''''Isoëtes''''', commonly known as the '''quillworts''', is a genus of plants in the class [[Isoëtopsida]] and order [[Isoëtales]]. They are [[lycopods]] and the only genus in '''Isoëtaceae'''. There are about 140 known species<ref name="Christenhusz-Byng2016">{{cite journal | author = Christenhusz, M. J. M., and Byng, J. W. | year = 2016 | title = The number of known plants species in the world and its annual increase | journal = Phytotaxa | volume = 261 | pages = 201–217 | url = http://www.mapress.com/file/e/pt00261p217.pdf | doi = 10.11646/phytotaxa.261.3.1 | issue = 3 | publisher = Magnolia Press }}</ref>, with a [[cosmopolitan distribution]] but often scarce to rare. Some [[botanist]]s split the genus, separating two South American species into the genus ''[[Stylites (genus)|Stylites]]'', although molecular data place these species among other species of ''Isoëtes'', so the genus does not warrant taxonomic recognition.{{Citation needed|date=December 2014}} |
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The name of the genus is |
The name of the genus is usually spelled ''Isoëtes''. The [[Diaeresis (diacritic)|diaeresis]] (two dots over the e) indicate that the o and the e are to be pronounced in two distinct syllables. Including this in print is optional; either spelling (Isoetes or Isoëtes) is correct<ref>[http://www.iapt-taxon.org/nomen/main.php?page=art60 International Code of Nomenclature for algae, fungi, and plants (Melbourne Code)] see section 60.6</ref> |
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==Description== |
==Description== |
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==Classification== |
==Classification== |
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Compared to other genera, '' |
Compared to other genera, ''Isoëtes'' is poorly known. Even after studies with cytology, scanning electron microscopy, and chromatography, species are difficult to identify and their phylogeny is disputed. Vegetative characters commonly used to distinguish other genera, such as leaf length, rigidity, color, or shape are variable and depend on habitat. Most classification systems for ''Isoëtes'' rely on spore characteristics, which make species identification nearly impossible without microscopy.<ref>{{cite book| title=Ferns and Fern Allies of Canada| last1=Cody| first1=William| last2=Britton| first2=Donald| year=1989| publisher=Agriculture Canada}}</ref> |
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Placed in its own family, Isoetaceae, the genus includes about 150 species worldwide.<ref>{{cite book | last=Taylor | first=W. Carl |author2=Neil T. Luebke |author3=Donald M. Britton |author4=R. James Hickey |author5= Daniel F. Brunton | year=1993 | title=Flora of North America | chapter=Isoëtaceae | publisher=Oxford University Press | volume=2 | page=64}}</ref><ref>Musselman, Lytton John. 2001. "[http://www.odu.edu/~lmusselm/plant/isoetes/Tipularia2001Full.pdf Georgia quillworts]". ''[[The Journal of the Georgia Botanical Society]]'' 16. 2-19, 40.</ref> |
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;Selected species |
;Selected species |
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Revision as of 12:58, 25 May 2016
| Isoëtes | |
|---|---|
| Isoëtes lacustris[1] | |
| Scientific classification | |
| Kingdom: | |
| Division: | |
| Class: | |
| Order: | [Isoëtales]]
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| Family: | Isoëtaceae |
| Genus: | Isoëtes |
Isoëtes, commonly known as the quillworts, is a genus of plants in the class Isoëtopsida and order Isoëtales. They are lycopods and the only genus in Isoëtaceae. There are about 140 known species[3], with a cosmopolitan distribution but often scarce to rare. Some botanists split the genus, separating two South American species into the genus Stylites, although molecular data place these species among other species of Isoëtes, so the genus does not warrant taxonomic recognition.[citation needed]
The name of the genus is usually spelled Isoëtes. The diaeresis (two dots over the e) indicate that the o and the e are to be pronounced in two distinct syllables. Including this in print is optional; either spelling (Isoetes or Isoëtes) is correct[4]
Description
Quillworts are mostly aquatic or semi-aquatic in clear ponds and slow-moving streams, though several (e.g. I. butleri, I. histrix and I. nuttallii) grow on wet ground that dries out in the summer. Quillwort leaves are hollow and quill-like, with a minute ligule at the base of the upper surface.[5]: 7 arising from a central corm. Each leaf is narrow, 2–20 centimetres (0.8–7.9 in) long (exceptionally up to 100 cm or 39 in) and 0.5–3.0 mm (0.02–0.12 in) wide; they can be either evergreen, winter deciduous, or dry-season deciduous. They broaden to a swollen base up to 5 mm (0.20 in) wide where they attach in clusters to a bulb-like, underground rhizome characteristic of most quillwort species, though a few (e.g. I. tegetiformans) form spreading mats. This swollen base also contains male and female sporangia, protected by a thin, transparent covering (velum), which is used diagnostically to help identify quillwort species. They are heterosporous. Quillwort species are very difficult to distinguish by general appearance. The best way to identify them is by examining the megaspores under a microscope.
Classification
Compared to other genera, Isoëtes is poorly known. Even after studies with cytology, scanning electron microscopy, and chromatography, species are difficult to identify and their phylogeny is disputed. Vegetative characters commonly used to distinguish other genera, such as leaf length, rigidity, color, or shape are variable and depend on habitat. Most classification systems for Isoëtes rely on spore characteristics, which make species identification nearly impossible without microscopy.[6]
- Selected species
- Isoetes acadiensis
- Isoetes alpina – New Zealand quillwort
- Isoetes andicola – (syn. Stylites andicola)
- Isoetes appalachiana – Appalachian quillwort
- Isoetes australis – Australian quillwort
- †Isoetes beestonii – (Late Permian, extinct)[7]
- Isoetes bolanderi – Bolander's quillwort
- Isoetes brevicula
- Isoetes brochonii – Pyrenean quillwort
- Isoetes butleri – Butler's quillwort
- Isoetes caroli
- Isoetes caroliniana - Carolina quillwort
- Isoetes drummondii – Drummond's quillwort
- Isoetes durieui – Durieu's quillwort
- Isoetes × eatonii – Eaton's quillwort
- Isoetes echinospora – spring quillwort
- Isoetes ecuadoriensis
- Isoetes eludens – elusive quillwort
- Isoetes engelmannii Engelmann's quillwort
- Isoetes flaccida – southern quillwort
- Isoetes gemmifera – (syn. Stylites gemmifera)
- Isoetes hieroglyphica
- Isoetes histrix – land quillwort
- Isoetes howellii – Howell's quillwort
- Isoetes inflata
- Isoetes ivones
- Isoetes jaeger
- Isoetes lacustris – lake quillwort
- Isoetes louisianensis – Louisiana quillwort
- Isoetes macrospora
- Isoetes malinverniana
- Isoetes maritima – maritime quillwort
- Isoetes melanopoda – black-footed quillwort
- Isoetes melanospora – black-spored quillwort
- Isoetes mongerensis – Monger quillwort
- Isoetes muelleri – Mueller's quillwort
- Isoetes nuttallii – Nuttall's quillwort
- Isoetes occidentalis
- Isoetes piedmontana – Piedmont quillwort
- Isoetes riparia
- Isoetes setacea
- Isoetes sinensis
- Isoetes taiwanensis
- Isoetes tegetiformans – mat-forming quillwort
- Isoetes tenella – spiny-spore quillwort
- Isoetes tenuissima – French quillwort
- Isoetes toximontana - green-spored quillwort from South Africa
- Isoetes tripus
- Isoetes tuckermanii
- Isoetes valida – Carolina or strong quillwort
- Isoetes velata
- Isoetes viridimontana – Green Mountain quillwort
Many species, such as the Louisiana quillwort and the mat-forming quillwort, are endangered species. Several species of Isoetes are commonly called Merlin's grass, especially I. lacustris, but also the endangered species I. tegetiformans and I. virginica.
Evolution
Fossilised specimens of I. beestonii have been found in rocks dating to the early Triassic.[7] Quillworts are considered by some[7] to be the last remnant of the fossil tree Lepidodendron 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.
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References
- ^ illustration from Otto Wilhelm Thomé Flora von Deutschland, Österreich und der Schweiz 1885, Gera, Germany
- ^ Reichenbach, H. G. L. (1828). Conspectus Regni Vegetabilis. p. 43.
- ^ Christenhusz, M. J. M., and Byng, J. W. (2016). "The number of known plants species in the world and its annual increase" (PDF). Phytotaxa. 261 (3). Magnolia Press: 201–217. doi:10.11646/phytotaxa.261.3.1.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ International Code of Nomenclature for algae, fungi, and plants (Melbourne Code) see section 60.6
- ^ Stace, C.A. (2010). New flora of the British Isles (Third ed.). Cambridge, U.K.: Cambridge University Press. ISBN 9780521707725.
- ^ Cody, William; Britton, Donald (1989). Ferns and Fern Allies of Canada. Agriculture Canada.
- ^ a b c Retallack, G. J. (1997). "Earliest Triassic Origin of Isoetes and Quillwort Evolutionary Radiation". Journal of Paleontology. 71 (3): 500–521. doi:10.2307/1306630. JSTOR 1306630.