Chapter 27, pages 558
Five Kingdoms-5 3:53-7:51
I. Characteristics
A. True roots
B. True stems
C. Microphylls in whorls at nodes
E. Sporangia borne in strobili
II Equisetum
A. One genus and about 25 genera in this Division
B. Habitat
1. Mostly cool and moist places
2. Equisetum arvense - only species of arid habitats
C. Distribution
1. All over the world
2. Not in Australia or New Zealand
D. Sporophyte structure
1. Herbaceous to shrubby
2. Rhizome
a. Grows horizontal just under the soil surface
b. Branched
c. Perennial
3. Roots - adventitious at stem and rhizome nodes
4. Stems
a. Up to five feet tall (one vine-like species that grows 36 feet long)
b. No secondary growth
c. Stems are annual and die down each year in the fall
d. Nodes and internodes present
e.
Stems
ribbed
and
furrowed
with the ribbing and furrowing
alternating
at the
nodes
f. Two stem forms:
(1) Sterile stems
(a) Contain chlorophyll and therefore are green
(b) Do not produce any spores
(c) Come up from the
rhizomes
after the
fertile
stems come up in the
spring
(d) Branching only occurs on sterile stems
i) Branching only occurs at the nodes
ii) Branching occurs below the microphylls
(2) Fertile Stems
(a) Contain no chlorophyll and therefore are light tan in color
(b) Usually the first stems to come up in the spring
(c) The strobilus is at the tip of the stem
(1) Causes the stem to grow in the length
(2) Causes the stem to be structurally weak at the nodes (called joint grass)
h. Cross section of stem
(1) Epidermis
(a) Has silica embedded in the epidermis
(b) Called scouring rushes
i) Named scouring rushes by the pioneers as they came west
ii) The "rush" name came because the stems were round
iii) The "scouring"
name came because they used them to scour their
dirty dishes
iv) The silica in the epidermis made them abrasive for scouring
(2) Cortex
(a) Parenchyma tissue
(b) Ring of
vallecular canals are embedded in the
cortex
opposite each
furrow
(3) Vascular bundles
(a) A ring of vascular bundles are embedded in the cortex opposite the ribs
(b) Each vascular bundle contains a carinal canal
(c) Endodermis is associated with each bundle
i. Reproductive structures
(1) Sporangiophores
(a) A special kind of sporophyll
(b) Best described as an "umbrella"
with sporangia attached at the ends of
the umbrella
ribs
(c) The spores are produced inside the sporangia
(2) Strobili - group of sproangiophores at right angles to main vertical axis
(3) Spores
(a) Four spores form from each spore mother cell
(b) The spores are homosporous
(c) The spores contain a thick double wall
(d) Elaters
i) Elaters are in the form of hydroscopic ribbons
ii) These hydroscopic ribbons circle the spore
iii) They aid in spore dispersal
(e) The spores are fragile and are viable for only a few days
j. Gametophyte
(1) Germinates from the spores
(2) About the size of a pin head
(3) Many erect delicate lobes one cell layer thick
(4) Produces antheridia and archegonia
(5) Sperm are multiciliated and spiral in shape
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