Rise of the sporophyte
Liverworts, hornworts, mosses, lycophytes
Dichotomous or pseudonmonopodial branching
Refers to equal branching
Microphyll – start with unvascularized leaves, and overtime the become larger, become
vascularized, giving rise to a leaf with a single vein. Really just describing a leaf of a lycopod
Pith = living parenchyma. Xylem preserves well in fossil record so people interested in classifying
Lycopods show actinostele and plectostele.
Protoxylem starts developing first, then metaxylem, with phloem in between the metaxylem.
Other thing that’s new here are the roots. In lycopods, where shoot goes up, root will emerge and
start to branch dichotomously. We don’t see dichotomous branching in angiosperms – it’s just
something that these meristems do.
A) shows how a fern branches, with recruitment of a meristematic cell
B) shows lycopod root dichotomous branching
What’s weird for this plant is when shoots branch, they also form a root that grows down the stem
and emerge closer to base of upright shoot
Homospory vs Heterospory
Homospory – all sports are the same, each spore germinate and produce bisexual gametophyte
(but may not be self fertile)
Heterospory – spores not equivalent, and produced by separate sporangia. Microspores give rise to