The Ferns

Spore dispersal Siphonosteles Megaphylls = the ferns

fern morphology: terminology ferns have megaphylls, commonly called fronds fern fronds typically have circinate vernation, expand by unrolling. Unexpanded fronds are often referred to as fiddleheads or croziers. in most ferns the stem is an underground rhizome, although in some groups it can be erect and stocky roots are adventitous and borne at the nodes sporangia are usually abaxial on fronds and occur in clusters called sori there are of two types of sporangia in the ferns: EUSPORANGIA and LEPTOSPORANGIA

More terminology and frond dissection twice- pinnate Petiole or stipe simple (entire) once-pinnate pinnate

Megaphyll

B C Siphonostele with nonoverlapping leaf gaps Siphonosteles with overlapping leaf gaps

Eusporangia Leptosporangia Sporangia sessile or short-stalked Large sporangia (> 0.5 mm in diameter) Sporangial walls several cells thick plus tapetum Sporangia have no specialized dehiscence cells Sporangia produce a large number of spores. Sporangia on long, slender stalks Small sporangia (< 0.1 mm in diameter) Sporangial walls that are 1 cell thick plus tapetum Sporangia usually have an annulus Sporangia produce relatively few spores (commonly 64) Polypodiales Ophioglossales Marattiales

The Marattiales, an order of eusporangiate ferns

Vegetative morphology of the Marattiales most species have short, upright, unbranched stems large pinnately compound leaves conspicuous swellings called pulvini occur at the bases of pinnae in many species two persistent, clasping stipules occur at each leaf base shoot borne roots are large, fleshy, and smooth

Members of the Marattiales have polycyclic siphonosteles

Reproductive morphology of the Marattiales eusporangia are abaxial on the leaf in two rows along veins eusporangia may be separate, unfused (Angiopteris spp.) or fused into a synangium (Marattia spp., Danaea spp.) separate, unfused eusporangia eusporangia fused into a synangium

Psaronius, a marattialean fern of the Late Carboniferous, had obconical stems

Section from distal end of stem below Psaronius stems were clothed with a massive mantle of adventitous roots for stability Section from distal end of stem below Lower stem section with substantial root mantle

The Polypodiales, leptosporangiate ferns

Eusporangium leptosporangium Spore dispersal Eusporangium leptosporangium Megaphylls

Examples of variously divided leaves 174 simple or entire 165 lobed 170 pinnatifid 166 & 171 pinnatisect 167 pinnate 159 bipinnate 162 bipinnatifid Examples of variously divided leaves

B C dictyosteles Siphonostele with nonoverlapping leaf gaps Siphonosteles with overlapping leaf gaps B C dictyosteles

A dictyostele is the most specialized type of siphonostele seen in the Polypodiales Leaf gaps