BIOL 2P93 Lecture Notes - Lecture 5: Lycopodium Clavatum, Psilotum, Cyatheales
4 Jul 2018
School
Department
Course
Professor
Seedless Vascular Plants Part 1
Vascular Land Plants: Evolutionary History
oBryophytes -> free living prominent gametophytes & sporophytes attached to &
nutritionally dependent on gametophyte
Gamete producing generations & need for water to help sperm swim to eggs
Water requirement accounts for their small size & ground hugging form
oVLP -> sporophytes are prominent than gametophytes & are free living
Water is not necessary for reproduction
Water is required for reproduction of some of the more primitive seedless
vascular plants
Plants w/ seeds (gymnosperm & angiosperm) the adaptations of cones/flowers
are important for reproduction
oEarly VLP changed the biosphere i.e. oxygen rate, carbonic acid rate, soil structure &
erosion character
Oldest VLP is Cooksonia spp.
414-408 mya & was a terrestrial component until the end of the early
Devonian
oTotal time span 433-393mya
oHad epidermis w/ cuticle, a cortex or parenchyma, sporangia on
the branch tips and a bundle of xylem of tracheid cells
oOldest plant to have a stem w/ vascular tissue
Transitional form b/n non-vascular bryophytes & VLP
oEvolution of conduction tissues xylem & phloem were used for water & food transport
oLignin synthesis & its incorporation into cell walls to support water conducting cells was
important
Makes cell walls rigid so the vascularized sporophytes can reach greater heights
oVLP branch through apical meristem activity at branch/stem tips
oBranched sporophytes of VLP produce multiple sporangia -> polysporangiate
oAncient VLP gave rise to more specialized forms
These plants had roots, functioning as soil anchorage & water & nutrient
transport
find more resources at oneclass.com
find more resources at oneclass.com
Had stems & leaves increasing photosynthesis
oGametophytic generation progressively reduced & become more protected &
nutritionally dependent on the sporophyte
oSeeds evolved providing the embryonic sporophyte w/ nutrients & means to survive
unfavourable environments
oVLP have been ecologically successful and are the dominant plant type on most
landscapes
Vascular Plant Body: Organization
oMorphological & physiological changes occurred b/n varying parts of the plant body
bringing about differentiation of roots, stems & leaves
roots comprise the Root System -> anchors plant & absorbs water/minerals
from soil
stems/leaves make up the Shoot System -> stems exposing photosynthetic
leaves to sun
Vascular System -> conducts water/minerals to the leaves & photosynthetic
products away from the leaves to other parts of the plant
oDifferent cell types in the plant body are organized into tissues, tissues organized into
tissue systems
3 tissue systems
Dermal Tissue Layer -> outer, protective covering (epidermis, periderm)
Vascular Tissue System -> makes up the conductive tissues
(xylem/phloem)
Ground Tissue System -> parenchyma, sclerenchyma, collenchyma. the
vascular tissue system is embedded here
find more resources at oneclass.com
find more resources at oneclass.com
Club moss sporophyte
o3 tissue systems shown
Dermal -> epidermis
Vascular -> embedded in the ground tissue
Ground -> mesophyll in leaf and cortex in stem/root
o
Primary Growth -> occurs close to root/stem tips and is initiated by the apical
meristem. Main function is to extend the plant body i.e. vertical growth
Primary tissues -> arise from apical meristematic growth
Primary Plant Body -> part of the plant body composed of these tissues
Secondary Growth is thickening of the stem/root due to 2 types of lateral
meristem activity
Vascular Cambium -> produces secondary xylem/phloem
Cork Cambium -> helps with production of secondary vascular tissues
oCork cambium forms of periderm -> outer protective layer that
replaces epidermis on woody stems
Secondary Plant Body -> made up of secondary vascular tissues &
periderm
Older trees produce a lot of secondary growth in terms of tree diameter
Vascular Plant Body: Organization (Xylem)
oTransports water/minerals from roots to aerial parts of the plant
oMovement is uni-directional (moves up the plant stem)
oOccurs in roots, stems, leaves
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Vascular land plants: evolutionary history: bryophytes -> free living prominent gametophytes & sporophytes attached to & nutritionally dependent on gametophyte. Gamete producing generations & need for water to help sperm swim to eggs. Water requirement accounts for their small size & ground hugging form: vlp -> sporophytes are prominent than gametophytes & are free living. Water is required for reproduction of some of the more primitive seedless vascular plants. Plants w/ seeds (gymnosperm & angiosperm) the adaptations of cones/flowers are important for reproduction: early vlp changed the biosphere i. e. oxygen rate, carbonic acid rate, soil structure & erosion character. 414-408 mya & was a terrestrial component until the end of the early. Devonian: total time span 433-393mya, had epidermis w/ cuticle, a cortex or parenchyma, sporangia on the branch tips and a bundle of xylem of tracheid cells, oldest plant to have a stem w/ vascular tissue.
