Roots Flashcards
Three (3) functions of roots
- Anchoring the plants firmly to substrate
- Absorbing water and minerals
- Producing hormone
Types of Root Systems
- Fibrous Root System
- Tap Root System
main root of a primary root system, growing vertically downward.
taproot
increase the surface area of a plant’s root system and can be found in great abundance in several plant species
lateral roots
cylindrical extensions of root epidermal cells that are important for acquisition of nutrients, microbe interactions, and plant anchorage
root hairs
External Structure of Roots
- root hairs
- area of cell differentiation
- area of cell elongation
- area of cell division
- root cap
Internal Structure of Roots
- root hair
- epidermis
- cortex
- stele
central core of the stem and root of a vascular plant, consisting of the vascular tissue (xylem and phloem) and associated supporting tissue
stele
outer layer of a stem or root in a vascular plant, lying below the epidermis but outside of the vascular bundles
cortex
Primary meristems
- Protoderm
- Ground meristem
- Procambium
- Apical meristem
Parts of stele
- endodermis
- pericycle
- phloem
- xylem
thin layer of tightly packed cells that act as an impermeable barrier or water repellant layer (the Casparian strip) through which water can move only one way, toward the center of the root system
endodermis
important tissue in roots, as this is the site where branch or secondary roots arise
pericycle
the continuous arrangement of protoplasts of a plant, which are interconnected by plasmodesmata.
Symplast
consists of non protoplasmic parts such as cell wall and intracellular space.
Apoplast
between protophloem and metaphloem
tangential
between companion cells and procambium cells
periclinal
different arrangements of the number of protoxylem groups in roots in cross-sectional view
- Diarch
- Triarch
- Tetrarch
- Polyarch
having two xylem strands or groups
diarch
having three xylem strands or groups
triarch
having four xylem strands or groups
tetrarch
having many protoxylem groups
polyarch
Features of Protoxylem and Metaxylem:
Time of formation
Protoxylem
- first formed xylem
Metaxylem
- late formed xylem
Features of Protoxylem and Metaxylem:
Life time
Protoxylem
- short period
Metaxylem
- long period
Features of Protoxylem and Metaxylem:
Fibers
Protoxylem
- lack fibers
Metaxylem
- has fibers
Features of Protoxylem and Metaxylem:
Vessels
Protoxylem
- narrow in diameter
Metaxylem
- broader vessels