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CALAMITES
“Arborescent
Horsetails”
of
the Carboniferous
MARY JOSEPH
ASST. PROFESSOR
DEPT. OF BOTANY
ST. ALBERT’S
COLLEGE, EKM
OCCURENCE
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These plants were medium-sized trees,
growing to heights of more than 10
meters (30 feet).
They were components of the under
stories of coal swamps of the
Carboniferous Period (around 360 to 300
million years ago).
Reconstruction
of Calamites
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Very few fossil plant specimens exist with all
the parts of the plant.. Paleobotanists don't
always know at first which stems, leaves,
seeds, cones, bark and roots belong to the same
plant, so they give separate species names to
the plant parts. These parts belong to the
Calamites tree:
� The stem: Calamites- in the form of
impressions and pith casts, Arthropitys,
Calamodendron, Arthroxylon- in the form of
petrifactions
� The leaves: Asterophyllites, Annularia
� The cones: Calamostachys, Palaeostachys
� The root: Asteromyelon
STEM
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The trunks of Calamites had a distinctive segmented, bamboolike appearance and vertical ribbing. The branches, leaves and
cones were all borne in whorls. The leaves were needle-shaped,
with up to 25 per whorl.
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Their trunks produced secondary xylem, meaning they were
made of wood. The vascular cambium of Calamites was
unifacial, producing secondary xylem towards the stem center,
but not secondary phloem.
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The stems of modern horsetails are typically hollow or contain
numerous elongated air-filled sacs. Calamites was similar in
that its trunk and stems were hollow, like wooden tubes. When
these trunks buckled and broke, they could fill with sediment.
This is the reason pith casts of the inside of Calamites stems
are so common as fossils.
ANATOMY
BRANCH SCARS
LEAVES
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The foliage of the horsetail
trees is divided into two
genera:
Asterophyllites, with rigid
leaves, arching up from the
node and often touching the
next whorl
Annularia, with softer
leaves forming oval, stellate
patterns
CONES
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Calamites reproduced
by means of spores,
which were produced in
small sacs organized
into cones.
RHIZOME & ROOTS
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They are also known to have possessed
massive underground rhizomes, which
allowed for the production of clones of
one tree. This is the only group of trees
of their period known to have a clonal
habit. This type of asexual
reproduction would allow them to
spread quickly into new territory, and
help to anchor them firmly in the
unstable ground along rivers and in
newly deposited delta sediments. The
rhizomes of Calamites look quite
similar to the stems in most cases, but
have nodes that get progressively
closer together as they approach the
apical area (the growth tip that spreads
outward through the soil).