THE GENUS ISOETES

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THE GENUS ISOETES (ISOETACEAE LYCOPSIDA) IN
SOUTHWEST ASIA
22 June 2007
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Lytton John Musselman Mohammad Al
Zein, Jay F Bolin, Old Dominion University W
Carl Taylor, National Science Foundation Mustafa
Keskin, Marmara University
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Features of Isoetes -morphology -evolutionary
patterns -taxonomic characters Review of Isoetes
in Turkey Review of Isoetes in Syria and Lebanon
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Features of Isoetes (known as quillwort in
English)
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What is a quillwort? Field characters
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Obligate hydrophytic, heterosporous lycopods with
spirally arranged sporophylls with a groove on
the adaxial surface, four air chambers arising
from a corm-like structure bearing forked root
tips
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Obligate hydrophytic. . . . . . . Isoetes often
grow in extremely sensitive aquatic environments
such as temporary ponds, streams, and
lakes. They are therefore good indicators of
environmental quality.
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Base of leaf is swollen, contains a sporangium
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Each leaf is therefore a sporophyll
Sporangia
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The extension of the sporophyll epidermis is the
velum, velum features have taxonomic value
NO velum coverage
ca. 95 velum coverage
ca. 25 velum coverage
Isoetes gymnocarpa
Isoetes schweinfurthii
Isoetes echinospora
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Examples
NO velum coverage
ca. 95 velum coverage
ca. 25 velum coverage
Isoetes gymnocarpa
Isoetes schweinfurthii
Isoetes echinospora
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Ligule Glosspodium Sporangium
Isoetes is one of the few genera of vascular
plants that possesses a ligule. The function is
unknown.
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There are two types of sporangia. Megasporangia
bear megaspores. The megaspores of Isoetes are
the largest in the Plant Kingdom, up to 900µ in
diameter
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Megaspores from various species showing diversity
of ornamentation
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Microsporangia bear microspores. They are about
1/10 the size of the megaspores
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Ploidy level is reflected in spore size
2n44
2n22
2n66
2n110
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The secret sex life of quillworts
is cryptogamic, that is, sex organs
are microscopic.
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Megaspore germinates to form megagametophyte
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Megagametophyte enclosed within the megaspore,
hence endosporic
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Microspore germinates to release. . .
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Microspore germinates to release. . .
motile sperm
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Now to the real thing!!
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Germinating spores
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Megagametophyte
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Young sporophyte
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Obligate hydrophyte with spirally arranged leaves
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groove on adaxial surface, four air chambers
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groove on adaxial surface, four air chambers
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groove on adaxial surface, four air chambers
diaphragm
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arising from a corm-like structure bearing
forked root tips
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Until recently it was assumed that scales were
found in only some Isoetes species.
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All species of Isoetes that we have carefully
examined have scales.
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Scales and phyllopodia are different Scales are
modified leaves, phyllopodia are indurated leaf
bases
Scales
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Scales and phyllopodia are different Scales are
modified leaves, phyllopodia are indurated leaf
bases
Phyllopodia
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However, in some species there is an
intergradation from scale to phyllopodium
Isoetes piedmontana
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How are Isoetes species identified?
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Answer With difficulty!
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All quillworts look similar! Size can range from
0.01 to 2.00 m
Isoetes butleri
Isoetes melanopoda
Isoetes mattaponica
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All quillworts look similar!
Isoetes butleri Kentucky, USA
Isoetes stellebossiensis South Africa
Isoetes olympica Syria
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All quillworts look similar! Lots of variability
in size in most species
Isoetes hyemalis from flowing water
looks different than terrestrial form
0.75 M
Terrestrial form
Submersed form
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Megaspores have traditionally been the most
reliable way to identify quillworts
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Until the advent of molecular techniques, megaspor
es were used to suggest patterns of phylogeny
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As recently as 20 years ago, hybrids were
considered to be extremely rare.
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Based on recent research, it is likely that most
Isoetes will interbreed and that hybrids are the
rule, not the exception.
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Hybrids exhibit heterosis
Isoetes altonharvillii
Isoetes valida Parent B
Isoetes engelmannii Parent A
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Misshapen microspores
In hybrids, spores are malformed due to unequal
separation at meiosis
Misshapen megaspores
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Evolutionary patterns in the genus
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Isoetes presents a classic example of reticulate
evolution, that is, hybridization followed by
polyploidy
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One example Isoetes engelmannii
(2n22) Isoetes valida (2n22) Isoetes
altonharvillii (2n22 and sterile) upon doubling
Isoetes appalachiana (2n44 and fertile)
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THE GENUS ISOETES (ISOETACEAE LYCOPSIDA) IN
SOUTHWEST ASIA
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The Genus Isoetes in Turkey
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Isoetes is a poorly known genus in Turkey
despite a good understanding of the flora
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Is this a pattern in other Southwest Asian
countries?
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Jermy recorded four taxa from Turkey Isoetes
olympica A.Braun, I. histrix Bory var.histrix, I.
histrix Bory var.subinermis Durieu and I.
durieuii Bory
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Isoetes olympica A.Braun
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Isoetes olympica A.Braun
I. histrix Bory var.histrix
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Isoetes olympica A.Braun
I. histrix Bory var.subinermis Durieu
I. histrix Bory var.histrix
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Isoetes olympica A.Braun
I. durieuii Bory
I. histrix Bory var.subinermis Durieu
I. histrix Bory var.histrix
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Are there only four taxa in Turkey ? Is this
number real ? What is their distribution?
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At present. . . .
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Isoetes olympica A. Braun Still known in Bursa
province
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Isoetes histrix Bory var.histrix Istanbul
(Anatolian European parts), Aydin (Menderes
massif), Izmir
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Isoetes histrix Bory var. subinermis Durieu, Usak
Province
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Isoetes durieuii Bory Istanbul
(AnatoliaEurope) Kocaeli, Çanakkale, Mugla
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Isoetes anatolica Prada Rolleri described in
2005 from Bolu-Abant lake.
After Prada Rolleri, 2005
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Isoetes anatolica Prada Rolleri
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Are there other Isoetes in Turkey?
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A few Isoetes need to be named. . .
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Antalya-Kemer, perhaps close to I. durieuii
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Ankara-Possibly a hybrid, further collections
needed
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Eskisehir-Perhaps another new species.
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Bursa-Uludag This plant was collected near the
type locality of Isoetes olympica. The plant
bears phyllopodia and has megaspores unlike I.
olympica.
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Istanbul The megaspores and microspores are
distinctive for Turkish quillworts
Mature spores are needed.
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Isoetes in Turkey Summary
Isoetes anatolica Prada and Rolleri Isoetes
durieui Bory Isoetes histrix Bory Isoetes
olympica A. Braun Several other taxa
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The Genus Isoetes in Syria and Lebanon
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Like Turkey, the flora of Syria and Lebanon has
been well studied Post did not record any
Isoetes Mouterde recorded two species from Syria
and Lebanon Isoetes olympica A. Braun,
and Isoetes hystrix Dur. forma subinermis Dur.
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Isoetes histrix Dur. forma subinermis Dur.
Isoetes olympica A. Braun
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Isoetes olympica
First described by A. Braun in 1867 and for many
years known only from the type locality near the
present day city of Bursa in western Turkey.
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Isoetes olympica was first described from
Mt. Olympus. Only a few specimens known.
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Discovered in Syria in the 1930s by Samuelsson
in the Jebel Druze area.
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Jebel Druze is a range of extinct volcanoes in
southern Syria
Jebel Druze
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Isoetes olympica habitat, Jebel Druze (now known
as Jebel al Arab)
April 2001
June 2001
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Isoetes olympica habit
Terrestrial form
Submersed form
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Isoetes olympica microspores
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Isoetes olympica Megaspores
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Isoetes hystrix Dur. forma subinermis
Dur. (Tentative determination)
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Nomenclatural Matters Isoetes histrix was
described by Bory in 1844 and later treated by L.
Motelay and Vendryes as I. hystrix in
1883 Isoetes hystrix Durieu var. subinermis
Durieu was described by Motelay and Vendryes in
1883 along with other varieties
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Nomenclatural Matters Cesca and Peruzzi (2001)
raised this taxon to species, Isoetes inermis
(Durieu) Cesca and Peruzzi In the flora of
Sardinia, I. h. var. subinermis is treated as
Isoetes gymnocarpa (Genn.) Braun
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Orthography and Nomenclature Isoetes histrix
Bory Isoetes hystrix Durieu
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Akkar Province
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Distribution of Isoetes histrix var. subinermis
in northern Lebanon and Syria
Syria
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Original description of Isoetes hystrix var.
subinermis
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Distinguishing I. histrix var. histrix from I.
histrix var. subinermis
There is no significant difference in the
essential characters that would enable us to
raise this variety to the rank of species. Il
ny a du reste aucune diff?rence importante dans
les caractères essentiels, ce qui ne nous
permet pas d?lever cette vari?t? au
rang despèce.
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Text refers to I. histrix var. subinermis,
plates to I. histrix forma subinermis
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Isoetes hystrix var. hystrix. Note persistent
leaf bases which characterize this taxon
This includes the French translation of
Brauns original descriptions of several relevant
taxa.
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Isoetes hystrix var. subinermis, on the other
hand, lacks phyllopodia and specialized scales
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Scales from I. histrix var. subinermis
from Lebanon
I. histrix var. histrix scales
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Isoetes histrix var. histrix and I. histrix var.
subinermis habits
Isoetes hystrix var. subinermis
Emergent
Submergent
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Isoetes histrix var. histrix and I. histrix var.
subinermis habits
Can I. histrix var. histrix grow submersed?
Image from htpp//D\Wild Plants of the British
Isles.htm
Isoetes histrix var. histrix
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Near Menges, Akkar Province Lebanon
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I. histrix var. subinermis occurs as both an
emergent and submergent
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And across the border in Syria. . .
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I. histrix var. subinermis, a tentative
determination
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Abundant in pools and wet areas
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I. histrix var. subinermis megaspores
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I. histrix var. subinermis microspores
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I. histrix var. subinermis megaspore
Isoetes olympica megaspores
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Isoetes histrix var. subinermis
Isoetes olympica
Leaf strands (collenchyma) are present in both
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The chromosome number is the same 2n22
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Are I. olympica and I. hystrix var.subinermis
the same taxon?

• Megaspores are similar
• Microspores are similar
• Growth form is similar (?)
• Both taxa are 2n22
• Both quillworts are in intermittent wetlands
• Collenchyma found in leaves of both
• Velum is different (incomplete in I. olympica)

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Differences between I. histrix var. histrix and
I. histrix var. subinermis

• I. histrix var. histrix
• 2n20
• phyllopodia and scales
• scales with dentition
• mainly coastal (?)
• Mediterranean and
• Atlantic coasts of Europe

• I. histrix var. subinermis
• 2n22
• scales only
• scales simple
• mainly mountains (?)
• Western and southern
• Europe, Northwest Africa

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Isoetes gymnocarpa (Genn.) Braun Is this
represented in the flora of Southwest Asia?
From Flora dell Isola di Sardegna
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Australasian
New World
Mediterranean
Gondwana
Med.
histrix v. subin.?
histrix v. histrix
coromandelina
melanopoda
yunguiensis
engelmannii
echinospora
taiwanensis
Lebanese
panamensis
jamaicensis
brevicula
olympica
australis
setacea
howelii
velata
kirkii
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99
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Simplified World ITS Isoëtes Clades
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Australasian
New World
Mediterranean
Gondwana
Med.
histrix v. subin.?
histrix v. histrix
coromandelina
melanopoda
yunguiensis
engelmannii
echinospora
taiwanensis
Lebanese
panamensis
jamaicensis
brevicula
olympica
australis
setacea
howelii
velata
kirkii
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The plants occurring near the Lebanon-Syria bord
er are likely a new taxon
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Simplified World ITS Isoëtes Clades
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Molecular data are not complete enough to
differentiate among Isoetes histrix var.
subinermis, I. histrix var. histrix, and I.
olympica.
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Hypotheses for further research
The genus Isoetes is poorly understood in
Southwest Asia Several new taxa are likely
present Hybrids occur Isoetes olympica and I.
histrix var. subinermis conspecific?
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?? How many taxa are there In Western Asia?
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Isoetes may be one of the least studied of all
genera of vascular plants in Western Asia!
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Thanks!!