Plant morphology

2. Topic Outline
I. Definition of Heterospory and Leptosporangiate
II. Heterosporous Order (Salvineales)
A. Family Marsileaceae
1. Genera
a. Marsilea
b. Regnellidium
c. Pilularia
2. Morphology
3. Reproduction
4. Habitat and Ecological Uses
B. Family Salviniaceae
1. Genera
a. Salvinia
b. Azolla
2. Morphology
3. Reproduction
4. Habitat and Ecological Uses
III. Studies

3. Heterospory
• A condition in which the life
cycle of a plant contains two
types of spores, microspores and
megaspores.
• Gives rise to distinct
microgametophytes and
megagametophytes.
• Necessary precondition for the
evolution of seeds.

4. Leptosporangiate
• From Greek word “Leptos”, fine or small
• Type of sporangium ontogeny wherein the
sporangium arises from a single surface cell
whose derivatives protrude from the surface
of the plant
• Leptosporangiate sporangia are small,
produce a definite number of spores and have
a wall layer of cells in thickness.

5. Salviniales
A. Family Marsileaceae
- Constituted of three genera:
1. Marsilea (approx. 50-75 spp.)
2. Regnellidium (1 spp.)
3. Pilularia (approx. 3-6 spp.) (Cuneo et al,
2013)
-Amphibious Ferns (except for 1
species of Marsilea which is
xerophytic)
1
2
3

6. Classification
Kingdom: Plantae
Division: Pteridophyta
Class: Pteridopsida
Order: Salvineales
Family: Marsileaceae
Genera: Marsilea
Regnellidium
Pilularia

7. MORPHOLOGY

8. Marsilea sp.
Description:
Rhizome : The stem is a long and slender rhizome
-Roots: primary root formed on the stem is short-lived and is soon replaced by
adventitious roots, which arise gradually at the nodes on the underside of the
stem
-Leaves: The leaves arise from the upper side of the stem and are arranged in
two alternate rows
Sporocarps: nut-like, epipetiola bodies, borne laterally on the petioles

9. Anatomy of the Rhizome
 Can perennates- which are
embedded in soil or mud
 Elongated, branched, stolon-
like stem
 Branches arise at the base of
the leaves
 Mature stem- arranged in
amphiphloic siphonostele form
 Pericycle cells
 covers the inner and outer
phloem
covered by endodermal
layer
 Pith may be parenchymatous or
 sclerotic

10. Anatomy of Leaf
and Petiole
• Leaflet veins-
Dichotomously
branched
• Sunken stomata-
both leaf surface
• Presence of upper
epidermis and lower
epidermis
• Mesophyll layer
– Spongy
– Palisade

11. Anatomy of Roots
• Adventitiously
branched
• Contains monarch and
diarch proto-
steles with exarch
arrangements
• Stele- surrounded by a
single layer
of pericycle and an
endodermis
• Inner cortex is
sclerotic, the outer
contains air chambers

12. Sporocarp Morphology

13. REPRODUCTION

14. Sporophyte
Reproduction:
Sporocarp
Sori
Spores

15. Diagram showing stages in the
dehiscence of Marsilea sporocarps.

16. Gametophyte Reproduction

17. Embryogeny
-Development of the embryo is
initiated several hours after
fertilization by nuclear and cell
division of the zygote.
1. Cytokinesis
2. 2nd cell division resulting to
formation of 4 cells (develops
into foot, leaf, stem and root
of the embryonic sporophyte.
3. Vegetative cells of
gametophyte are stimulated
to divide as an embryonic
sporophyte develops and
forms a sheathing calyptra .
4. Surface cells of the
gametophyte tissue develop
rhizoids
5. Cells develop chloroplast and
growth is rapid

19. A. Marsilea drummondii (SEM
longitudinal radial section)
B. Marsilea drummondii
(transverse logitudinal section)
C. Marilea drummondii sorus
D. Marsilea mutica sporocarp
H. Marsilea sporocarp wall
Legend:
sw- sporocarp wall
S1 and 2-sorophore segenents
Vb-vascular bundle
So-sorus
Me-magasporangia
Mi-microsporangia
In-indusium
Re-receptacle
S-sorophore
Lv-lateral vein
E-epidermal zone
sl- sclerenchymatous zone
Pa-parenchyma zone
Sc-stomatal chamber
Hb-hair base

20. Regnellidium diphyllum
Description:
-characterized by having highly reduced pinnately compound leaves
-having sori and sporangia enclosed in a specialized structure known as
a sporocarp that has a sclerenchymatous wall
-bearing micro- and megaspores that have a conspicuous proximal, six
or seven-lobed ornament or gelatinous extension subtended by
a rim (Marsilea) known as an acrolamella

21. E. Regnellidium diphyllum sporocarp
H. Regnellidium diphyllum sporocarp
wall
Legend:
Sw-sporocarp wall
S-sorophore
In-indusium
Me-megasporangia
Mi-microsporangia
Re-receptacle
E-epidermal zone
sl- sclerenchymatous zone
Pa-parenchyma zone

22. Pilularia sp.
Description:
- Rhizomes short- to long-creeping, branching, bearing roots at nodes, bearing septate
hairs or almost glabrous.
- Leaves monomorphic, not articulated to rhizome, arising at nodes, with long stalks
lacking lamina segments, herbaceous, glabrous.
- Veins greatly reduced, undivided.
- Sporocarps globose, sessile or stalked, hardened, hairy, attached to the rhizome at the
base of the leaf stalks, opening with two valves, each containing at least two sori. Each
sorus containing both mega- and microsporangia. Megaspores spheroidal to
slightly ellipsoidal, plain to slightly undulate; microspores spheroidal, and plain, papillate
or rugulate.

23. F. Pilularia globulifera sporocarp
I. Pilularia globulifera sporocarp
wall
Legend:
Sw-sporocarp wall
S-sorphore
Re-recptacle
Mi-microspore
In-indusium
E-epidermal zone
sl- sclerenchymatous zone
Pa-parenchyma zone

24. Habitat and Uses
• -Used as vegetation for some animal, cultivated as
ornamental and has found to have nerve relaxant
nature and curative properties for various other
ailments of nervous system and its nutritional value

25. Studies on Marsileaceae
Comparative Morphology of Reproductive Structures in Heterosporous Water
Ferns and a Reevaluation of the Sporocarp
Nathalie S. Nagalingum, Harald Schneider,y and Kathleen M. Pryer (2006)
Structure and Function of spores in the Aquatic Heterosporous Fern Family
Marsileaceae
Harald Schneider and Kathleen M. Pryer (2002)
Ecophysiological Traits of Leaves of Three Marsilea Species Distributed
in Different Geographical Regions
Tai-Chung Wu and Wen-Yuan Kao (2011)
Marsilea quadrifolia linn. - A Valuable Culinary and Remedial Fern in
Jaduguda, Jharkhand, India
Prafulla Soni and Lal Singh

26. Salviniales
B. Family Salviniaceae
- Constituted of 2 Genera:
1. Salvinia (approx. 12 spp.)
2. Azolla (approx. 7 spp.)
(Nagalingum et al, 2008)
2
1

27. VEGETATIVE MORPHOLOGY

28. Salvinia sp.
Description:
- Stems: dichotomously branched rhizomes, protostelic and aerenchymatous
- Leaves: simple, dimorphic (fertile different from sterile), aerenchymatous, at
maturity in whorls of three (2 floating, 1 submerged and root-like), blades
round to oblong, entire with water repellent trichomes in upper surface
- Sporocarps: sporocarp which is interpreted as modified sorus with the
indusium functioning as protective wall is globose, heterosporous, each bearing
either one megasporangium or several microsporangia at maturity

29. Salvinia sp.
A. Salvinia
oblongifolia
fertile node
B. Salvinia
oblongifolia
submerged organ
C. Salvinia
auriculata sorus
D. Salvinia minima
fertile branch
E. Salvinia
oblongifolia sorus
F. Salvinia
oblongifolia sorus
G. Salvinia
auriculata sori

30. Azolla sp.
Description:
-consist of branching stems densely clothed with alternate bilobed
leaves
-Each leaf is composed of chlorophyllous dorsal lobe and a
submerged achlorophyllous ventral lobe.
-have true roots that arise endogenously at intervals along the stem
-The roots bear root hairs as long as they exist.
-Sporocarp: Formed in groups of two or four in the axil of the dorsal
lobe of a basal leaf of a branch

31. SPOROCARP MORPHOLOGY

32. Azolla
sp.
A. Azolla nilotica
fertile plant
B,C. Azolla
nilotica
reproductive
units
D. Azolla nilotica
reproductive
units
E. Azolla
filiculoides
megasporangiate
sorus
F. Azolla
filiculoides sorus

33. Azolla Life Cycle

35. Schematic drawings of spore-bearing structures
of Marsileaceae (A, B) and Salviniaceae (C, D).

36. Studies on Salvinia and Azolla
Phytoremediation Potential of Aquatic Macrophyte, Azolla
Anjuli Sood, Perm L. Uniyal, Radha Prasanna, Amrik S.
Ahluwalia
Heavy metal induced physiological alterations in Salvinia natans
Bhupinder Dhir, P. Sharmila , P. Pardha Saradhi , S. Sharma , R. Kumar ,
Devinder Mehta