PALEO LABORATORY # 8, PAGE 1
PALEO LAB VIII - LAND PLANTS AND PALYNOLOGY
The study of fossil protists and plants is conducted by micropaleontologists and
The field of paleobotany, involving the study of fossil plants, may be divided
into a number of subdisciplines.
This study involves four of the five kingdoms of organisms and
encompasses both the study of large organisms and micropaleontology as well.
Most of these
organisms produce their energy by means of photosynthesis.
We have discussed many of the smaller representatives of photosynthetic organisms during
our micropaleontology lab.
The lab here discusses the land plants; photosynthetic metazoans of
the Kingdom Plantae.
It is believed that green land plants (Kingdom Plantae) evolved from ancestors belonging to
the Chlorophyta (grass-green algae).
Biochemical similarities between the two groups include
the presence of chlorophylls a and b, true starch, and cellulose in their cell walls.
Plantae include plants in which the fertilized egg develops into an embryo which is enclosed
within a protective covering.
Another characteristic of sexually reproducing green land plants is
Alternation of Generations.
In this there are multicellular gamete-producing organisms
(Gametophytes) alternating in the life cycle with
multicellular spore-producing organisms
The Kingdom Plantae contains two morphological groups, the bryophytes
(mosses, liverworts and hornworts) and the tracheophytes (vascular plants).
Of the two, the
tracheophytes are the most important paleontologically and include several divisions.
Tracheophytes, or vascular plants, are characterized by the presence of conducting cells
(xylem and phloem), and usually possess roots, stems and leaves.
Roots are subterranean; the
subaerial portions of plants are termed shoots.
The xylem and phloem form the internal transport
system that connects all parts of the plants.
Other vascular plant characters include an external
waxy covering (Cuticle) that aids in reducing desiccation, a high volume to surface ratio, and
differentiation of the shoot system into stem, Foliage (leaves) and reproductive organs.
Vascular Plant Structure
Because of the presence of rigid tissues, tracheophytes can reach very large size.
Also, due to
the presence of these resistant conducting systems and waterproofing cuticle structure, vascular
plants are more frequently fossilized than fungi, bryophytes and most algae.
The conducting cylinder in the root and stem of vascular plants is termed the Stele.
center of the stele there is typically an area of soft tissue that is used in food storage termed the
Stems of many primitive land plants lack the pith and are termed Protostelic.
most plants possess a pith that is surrounded by wood, or Xylem.
The xylem is actually dead
tissue through which water and minerals are transported.
The principle food transport system,
the Phloem, surrounds the xylem.
However, as phloem transports sugars it is typically not