BIOA02H3 Lecture Notes - Lecture 4: Urtica Dioica, Root Cap, Trichome
BIOA02 Module 1, Lecture 4: Plant Cells and Plant
Tissues
Complex Tissue: epidermis (leaf)
Trichome = hair
Can be short or long
Stoma is made out of two guard cells making up the plethora
Cuticle consists of a layer
Epidermal Hairs (root)
Cells grow root hairs that can be either branched or unbranched depending on the cell
Meristem is hidden under the root cap
Root hairs are inserted and are very tiny and fragile, single cell units, short lived
➢ Takes up water and nutrients in between soil particles
➢ Average life span is a week-3 weeks
➢ Will grow new additions of root hairs
Epidermal (Stinging) Hairs
Stinging nettle (urtica dioica)
Trichrome that is enforced by silica tips that make it dangerous to predators that attack the
plant
Contains chemicals that will form wells on skin when pricked
Grows as invasive species in north America, common in Europe
Chemical defense for the plants to protect themselves
Conical Epidermis
Roses have a velvety sheen
The light is reflected due to the conical epidermis
Epidermal Platelets
Takes design of trichrome and turns it into an umbrella shaped surface
Strongly modified hairs that forms platelets
A small greenhouse is created under the platelets because some sunlight is shaded away
➢ Slows down water loss
e.g. Silverberry
H20 Repellent Epidermis
Lotus is an aquatic plant
Don’t want a lot of water building up on leaves, epidermis grows nobs to coalesce water
onto the nobs and not the actual surface of the lotus leaves
Lotus keeps clean with the epidermis, water cleans the surface and takes away all the dust
Epidermal Sensing Hairs
E.g venus flytrap
➢ Epidermal trichomes can sense when hairs are touched by the insect
➢ Each venus flytrap has 6 hairs on each
➢ Turns into a death trap for insects, carnivorous plant
Pitcher Plant
When insects fly around inside the pitcher plant, it has grooves across the plant that helps
the insect get out
Once the insect reaches the rim it is very slippery because of moisture and waxy cutin, it
falls into the lethal liquid
Cliff area is very slippery
Long-lived Plants
Wear and tear of epidermis
As the stem grows and gets wider the epidermis rips open and creates holes in the
epidermis
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Document Summary
Bioa02 module 1, lecture 4: plant cells and plant. Stoma is made out of two guard cells making up the plethora. Cells grow root hairs that can be either branched or unbranched depending on the cell. Root hairs are inserted and are very tiny and fragile, single cell units, short lived. Takes up water and nutrients in between soil particles. Average life span is a week-3 weeks. Will grow new additions of root hairs. Trichrome that is enforced by silica tips that make it dangerous to predators that attack the plant. Contains chemicals that will form wells on skin when pricked. Grows as invasive species in north america, common in europe. Chemical defense for the plants to protect themselves. The light is reflected due to the conical epidermis. Takes design of trichrome and turns it into an umbrella shaped surface. A small greenhouse is created under the platelets because some sunlight is shaded away.
