VASCULAR

1. The Ferns

2. Megaphylls
Siphonosteles
Spore dispersal
= the ferns

3. 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

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

5. Megaphyll

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

7. • 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
Eusporangia Leptosporangia
Ophioglossale
s
Marattiales
• 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.

8. The Marattiales, an order of eusporangiate ferns

9. 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

10. Members of the Marattiales have polycyclic
siphonosteles

11. 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

12. Psaronius, a marattialean fern of the Late Carboniferous, had obconical stem

13. 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

14. The Polypodiales, leptosporangiate ferns

15. Megaphylls
Eusporangium leptosporangium
Spore dispersal

16. 174 simple or entire
165 lobed
170 pinnatifid
166 & 171 pinnatisect
167 pinnate
159 bipinnate
162 bipinnatifid
Examples of
variously divided
leaves

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

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