Spore Shedding Vascular
Plants
Psilotum
Lycopodium
Equisetum
Psilotum nudum (whisk fern)
Psilotum nudum (whisk fern)
http://imagenes.infojardin.com/sube/images/cqs1194212302m.jpg
Psilotum has a stem
doing virtually all the
photosynthesis, with
dichotomous branching,
enations without
vascular tissue, and
yellow synangia in the
axils of the enations.
Below ground, the stem
is not photosynthetic but
the epidermis forms
rhizoids for anchorage.
The plant thus lacks
roots and leaves with
underground stem
(rhizome) doing the
anchorage functions.
Psilotum stem cross section
radial exarch triarch actinostele
guard cells
epidermis cutin
PSN cortex
lignified cortex
respiring cortex
phloem
metaxylem
protoxylem
Protosteles:
haplosteles
actinostele
plectostele
Siphonosteles:
siphonostele
solenostele
dictyostele
cortex
phloem
xylem
cortex
phloem
xylem
pith
leaf gap
leaf trace
eustele
dicot
stem
atactostele
monocot
stem
Psilotum stem specimen more than triarch
http://sols.unlv.edu/Schulte/Anatomy/Stems/PsilotumWhole.jpg
Psilotum rhizomes with rhizoids
http://upload.wikimedia.org/wikipedia/commons/thumb/3/3b/Psilotum_nudum_Rhizome.jpg/800px-Psilotum_nudum_Rhizome.jpg
http://www.dipbot.unict.it/sistematica_es/Immagini/21001.JPG
Psilotum rhizome cross-section
http://www.dipbot.unict.it/sistematica_es/Immagini/21001.JPG
Psilotum stem demonstrates
dichotomous branching,
enations (no vascular tissue)
and two of the three sporangia
in a single synangium
Psilotum sporangium (a
three-parted synangium)
This specimen has shed
its spores into the wind
and so the sterile jackets
are empty.
At the bottom of the view
is a partial stem crosssection showing:
epidermis, cortex and a
portion of the vascular
cylinder.
http://kentsimmons.uwinnipeg.ca/2153/Psilotum_gametophyte.jpg
antheridia
http://www.siu.edu/~perspect/01_sp/pics/psilotum.jpg
http://kentsimmons.uwinnipeg.ca/2153/psilotAnthLowMag.jpg
archegonium
Psilotum gametophyte
tissues all haploid
http://kentsimmons.uwinnipeg.ca/2153/psilotoArchigonium.jpg
Psilotum gametophyte (SE to NW) and sporophyte (Y-shape)
The photo is flipped and cropped. Some versions of Powerpoint may fail to retain this making the labels erroneous!
1N gametophyte
1N antheridium
2N rhizome
2N rhizoid
1N rhizoid
Cooksonia
Earliest
Land
Plants
from the
Early
Devonian
Rhynia