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Vascular Plants Without Seeds (Lycophyte (sporangia # (clustered together…
Vascular Plants Without Seeds
Early Vascular Plants
Rhyniophytes
Equal dichotomous branching
both branches equal in size
homosporous
no separate microspores and megaspores
Zosterophyllophytes
small herbs without secondary growth
sporangia
lateral
opened transversely
exarch protostele
#
homosporous
xylem structure
2 types
protostele
center is solid mass with no pith
endarch protostele
protoxylem is located in the center
exarch
metaxylem in the center and protoxylem on the edges
Lycophyte
sporangia
#
lateral
clustered together in "cones"
protection
exarch protosteles
microphylls
have true roots
heterospory
microspores and megaspores
Euphyllophytes
trimerophytes
overtopping
pseudomonopodial branching
single main trunk
Megaphylls
leaves that evolved from branch systems, present in all seed plants
evolution summarized by the
telome theory
sporophyll
Monilophytes
3 snyapomorphies
roots have exarch xylem
megaphylls
30-kilobase inversion in plastid of DNA
sister clades
lignophytes
woody plants
Equisetophytes
contain horsetails
no secondary growth
small megaphylls
#
true roots present at nodes
sporangiophore
true monopodial growth
Ferns
leptospornangiate
12,000+ species
can be found in many habitats
sporophyte
#
endarch siphonostele
true roots
megaphyllous leaves
#
homosporous
#
two groups are heterosporous
Eusporangia
fundamental type
surface cells undergo periclinal divisions
outer cells develop into sporangium wall
inner cells proliferate into sporogenous tissues
Leptosporangia
single surface cell divides periclinally
few spores produced
thin covering of sterile cells
Vascular cryptograms
#
ferns and fern allies
vascular tissue
