2101 - Roots Flashcards
Organs definition
Different type of tissues working together for a unique function.
Root
Stem
Leaf
Primary functions of Roots
Anchorage
Absorbs water from the soil
Absorbs minerals from the soil
Tap Root system
In most Dicotyledon species, first root to emerge is the radicle. The Radicle develops into dominant and main root with secondary lateral roots branching.
Taraxacum official (Dandelion)
Fibrous Root system
In some Dicotyledon species, radicle does not develop into tap root.
Many lateral roots grow and develops a fibrous root system.
Tagetes patula (French Marigold)
Adventitious root
A root which develops from a structure other than an existing root (stem or leaf).
Root Hairs
Tiny elongated outgrowths from the epidermis. Behind the zone of elongation. Increase the water-absorbing area of the roots.
Root Cap
Sacrificial cap of mesophyll cells that protect the apical meristem, as the root pushes though the soil.
Apical Meristem
Area of rapid cell division. Primary growth point of the root.
Zone of Elongation
(above meristem) Meristematic cells increase in size to push the root tip through the soil.
Zone of differentiation
Root cells have matured and become specialised - such as epidermal or vascular.
No cuticle on the root epidermis for wager absorption.
Lots of root hairs.
Dicot Cross section
Vascular bundles arranged in star formation. Has Vascular cambium.
Monocot Cross section
Vascular bundles arranged in rings. Does not have Vascular cambium (no secondary thickening).
Epidermis
Single layer closely packs cells, protective cover.
Cortex
gives structure to the root. Mainly loosely packed parenchyma cells.
Stele (Vascular Cylinder)
Contains Phloem, Xylem, Vascular Cambium (in dicots) and Pericycle.
The inner portion (like a carrot). Does not include endodermis.
Vascular Cambium
Only in Dicotyledons, responsible for secondary thickening.
Pericycle
Outer layer of Vascular Cylinder. Lateral roots emerge from meristematic tissue in the Pericycle.
Phloem
Transport of Sugars
Xylem
Transport Water and Minerals
Endodermis
Single layer of cells found only in roots, encircling the vascular tissue.
Regulates water and mineral movement between the Cortex and the Xylem.
Casparian Strip
Waterproof band of material inside the Endodermal cells. This protects the root from entering soil solution.
Dicot vs Monocot rooting system
Dicots
Produce a radical which becomes a tap root.
Lateral roots from from the pericycle.
Monocots
Produce a radical, but it quickly dies off.
Have fibrous roots derived from the stem.
Root Adaption - Food Storage
Store food in enlarged roots or tubers.
Example of perennation.
Dauscus carota (carrot)
Dahlia ‘Bishop of Leicester’
Root Adaption - Additional Support
Plants produce prop roots to help support their stems and branches.
Zea mays (Sweetcorn)
Root Adaption - Water Storage
Aerial roots of epiphytic plants store water.
Orchid
Root Adaption - Reproduction
Suckers - adventitious buds that grow into shoots.
Rubus idaeus (Raspberry) Rumex acetosella (sheep sorrel)
Root Adaption - Climbing
Adventious roots from stems, cling to surfaces for height (light/polination)
Hedera helix (ivy)
