Lycophytes – first group of tracheophytes, produce tubes that transport water under real tension
Polytomy at the moment
Many ferns are epiphytes – two distinct types of leaves that enable it to thrive in angiosperm trees,
not necessarily in the elbow of a branch.
Early diverging plants, but in shadow of angiosperms – which is why so many epiphetic. Early
diverging, but not necessarily primitive.
Fern body plan
Rhizome, roots grow out of it
Frond are leaves – compound leaves.
Rhizome produces primordial, and primordial can become leaves.
In compound leaves, additional primordial produce pennae, leaf growing on compound structure.
We recognize that it’s a compound leaf at developmental level.
Single pyramidal initial apical cell, shoot apical meristem with leaf primordial covered in scales.
Each compound leaf associated, in general, with its own root. Develops sometimes off petiole or
base of leaf itself, but in general develops from pericycle in association with each leaf.
Rhizome can branch – growing along the ground. Variable organization of stems and leaves.
Stemleafbud but sometimes bud more closely associated with stem or with leaf. Three different
pictures in same plant so makes classifying based on thee kinds of stelar architecture confusing.
Circinate Vernation – this will definitely be on a final exam. As these fronds develop, they uncurl.
When tiny, lots of cell division, produces coiled structure, and during cell elongation phase, uncurl,
so each pinnae rolls outward.
Sporangia in sori on abaxial (underside) kind of leaf. Homosporous, so only one kind. Everything is
just the same sporangia.
Spores germinating after dormancy buried in soil – if on surface a female gametophyte is growing,
it can produce antheridiogens (chemicals) and spores deeper in soil will germinate, with elongated
filamentous growth to bring male gametophyte toward female.
Antheridiogens – increase in size. At first, mostly sterile, as get bigger, more likely to develop as
male, and over time, if no successful sterilization event, develop both antheridia and archegonia
and they will self fertilize. Large gametophytes that have a lot of resources will likely develop as
Ophioglossales – produces simple leaf and instead of spores on underside, it produces a fertile
spike (2 rows of sporangia)
With Marattiales, start to see more ferny tings – foliar borne sporangia (on leaves, not spike),
circinnate vernation, green photosynthetic gametophyte, complex leaves.
Equisetum – horsetails.
Produces a strobilus – spores in terminal structure
But also homosporous, with bisexual gametophytes, exosporic (gametophytes develop outside
Does have intercalary meristems Leaves are incredibly reduced, grow up in a sheathing form
Center of stem is hollow, protoxylem destroyed and produces another series of canals. Lightweight
construction to create axis that can stand up, but doesn’t use wood to stand up like trees, like
lycopods reinforces epidermis to make itself more rigid and pro