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Unofficial RHS Level 2 Study Guides For Plant Growth and Development
Clear, Simplified Notes to Help You Understand Each Topic with Confidence
The unofficial RHS Level 2 Study Guides for Plant Growth and Development, created by Garden Learners, are designed to make complex topics easier to understand.
Each study guide is an unofficial course companion that follows the RHS syllabus, written specifically for students studying horticulture at Level 2, and is ideal for use alongside lectures, during revision, or simply to clarify tricky topics.
Whether you’re using it with books, Principles of Horticulture by Adams et al., or Horticulture at Level 2 Unit 1 and Unit 2 by Barnaby Millard, or just want a clear, reliable way to learn the RHS Level 2 Principles course, you’re in the right place.
RHS Level 2 Certificate in the Principles of Plant Growth
Unit 1
Plant Science I
Scientific and Common Plant Names
The Importance of Scientific Names
- Importance of scientific names and their international use.
- Limitations of common names.
- Taxonomic hierarchy from Kingdom to Species.
- Explanation of plant families, genera, species, subspecies, varieties, forma, cultivars, and hybrids.
- Formatting conventions for botanical names, including correct italicisation, capitalisation, and use of symbols.
The Concept of Major Plant Groups
Overview of six key groups of land plants:
- Bryophytes (mosses)
- Pteridophytes (ferns)
- Gymnosperms (conifers)
- Angiosperms (flowering plants)
- Monocotyledons
- Eudicotyledons
Key structural, reproductive, and ecological traits of each group.
Practical garden examples for each group.
How External Characteristics Can Be Used To Group Plants
- Use of external traits (flowers, stems, leaves, roots) to classify plants.
- How traits determine placement in family, genus, species, variety, and cultivar categories.
- Comparison between naturally occurring plant groupings (e.g. species, varieties) and human-made ones (cultivars).
How Growth Stages Impact External Characteristics, e.g. Juvenile Growth
Topics covered:
Juvenile Stage
- Leaf shape variation (heterophylly)
- Flexible stems, adventitious roots, and thorns
- Inability to flower or form seeds
- Better rooting potential from cuttings
Adult Vegetative Stage
- Stable, species-typical leaf forms
- Woody, upright stems
- Increased lateral growth and internode length
Adult Reproductive Stage
- Onset of flowering and fruiting
- Resource shift toward reproduction
- Structural changes in growth habit
Senescence
- Decline in flowering and growth
- Leaf drop and eventual death (especially in annuals)
Real-life horticultural applications
- Propagation advice (use juvenile material)
- Coppicing and pollarding to maintain juvenile traits
- Use of juvenile traits in hedging for winter leaf retention
The Concepts of Plant Breeders’ Rights (PBRs) and Restrictions on Propagation when applied to a named variety.
- Definition and purpose of PBRs as intellectual property.
- Criteria for granting rights (DUS: Distinct, Uniform, Stable).
- Legal restrictions on propagating and selling protected cultivars.
- Differences between cultivar names and trade names.
- Real-world examples such as Rosa ‘Gertrude Jekyll’ and Heuchera ‘Obsidian’.
Lifecycle Adaptations
- What a life cycle is – from germination to seed production and death.
- Why adaptations matter – including responses to disturbance, climate, and competition.
- Ephemeral plants – complete their cycle in weeks to exploit short favourable conditions (e.g. Cardamine hirsuta).
- Annuals – complete their life cycle in one season, investing all energy in seed production (e.g. Helianthus annuus).
- Biennials – grow vegetatively in the first year and flower in the second (e.g. Digitalis purpurea).
- Herbaceous perennials – survive through underground storage organs and regrow each year (e.g. Hemerocallis).
- Woody perennials – have permanent above-ground structures and live for decades or longer (e.g. Quercus robur).
External Parts Of The Plant
Characteristics of External Plant Structures
Identifies visible structures and variations:
- Root types: taproot, fibrous, adventitious
- Stem features: nodes, internodes, buds, lenticels, bark, modifications (e.g. stolons, rhizomes)
- Leaf features: shape, arrangement, margin, venation
- Flower types and structures: bisexual, monoecious, dioecious
- Fruit types: fleshy, dry, dehiscent/indehiscent
Functions of External Plant Structures
Explains the purpose of each plant part:
- Roots: anchorage, absorption, storage, transport
- Stems: support, conduction, growth, storage/climbing
- Leaves: photosynthesis, transpiration, gas exchange
- Flowers: reproduction and pollinator attraction
- Fruits/Seeds: protection and dispersal
Use of External Plant Structures for Identification
- Shows how external features help classify plants into taxa:
- Roots: taproot vs fibrous for monocot/eudicot ID
- Stems: bud arrangement, lenticels, bark texture
- Leaves: margin, shape, venation, arrangement
- Flowers: part numbers, symmetry, inflorescence type
- Includes comparison tables and diagnostic traits for field ID.
- Offers a quiz to reinforce plant identification skills.
Internal Plant Structures
Characteristics, Arrangement, Function and Horticultural Importance of Internal Structures
- Internal structures of roots
- Internal structures of stems
- Internal structures of leaves
- Arrangement and characteristics of key tissues (e.g. epidermis, xylem, phloem, cambium, mesophyll)
- Function of each tissue in relation to water, nutrient, and sugar movement
- Horticultural relevance of each tissue type (e.g. transplanting, pruning, drought tolerance)
- Visual indicators of plant health related to internal structures
Pollination and Fertilisation
The Importance of Pollination and Fertilisation
Definition and types of pollination (self-pollination and cross-pollination)
Agents of pollination (insects, animals, wind, water)
Horticultural importance of pollination (including examples of food crops and pollinator-friendly plants)
Process of fertilisation in flowering plants, including double fertilisation
Importance of pollination and fertilisation for plants, ecosystems, and humans
Adaptations for pollination, with examples of insect-pollinated and wind-pollinated flowers
Mechanisms to avoid self-pollination (e.g. protandry, protogyny, monoecious and dioecious species)
Environmental factors affecting pollination and fertilisation (temperature, rainfall, wind, light levels, nutrients)
Gardening tips to support successful pollination and fertilisation
The Processes of Pollination and Fertilisation
Definition and purpose of pollination and fertilisation in flowering plants.
Key terminology associated with each process (e.g. stigma, anther, pollen tube, zygote).
Types of pollination: self-pollination and cross-pollination.
Agents of pollination, including insects and wind, have adaptations for different flower types.
Step-by-step sequence from pollination through to fertilisation and seed/fruit formation.
Double fertilisation in angiosperms.
Mechanisms to prevent self-pollination, such as protandry, dioecy, and heterostyly.
Relevance to horticulture, including improving crop yield and biodiversity.
The Processes of Pollination and Fertilisation
Definition and purpose of pollination and fertilisation in flowering plants.
Key terminology associated with each process (e.g. stigma, anther, pollen tube, zygote).
Types of pollination: self-pollination and cross-pollination.
Agents of pollination, including insects and wind, have adaptations for different flower types.
Step-by-step sequence from pollination through to fertilisation and seed/fruit formation.
Double fertilisation in angiosperms.
Mechanisms to prevent self-pollination, such as protandry, dioecy, and heterostyly.
Relevance to horticulture, including improving crop yield and biodiversity.
Functions of Plant Parts Involved in Pollination and Fertilisation
Overview of Pollination and Fertilisation: Introduction to their role in plant reproduction.
Functions of Flower Parts:
- Carpel (stigma, style, ovary, ovule) – female reproductive role and pathway to seed and fruit formation.
- Peduncle and Receptacle – structural support.
- Sepals and Petals – protection and pollinator attraction.
- Stamen (anther + filament) – male reproductive role.
- Pollen grain – structure and function in fertilisation.
The Agents of Natural Pollination
Overview of Pollination Agents: Introduction to biotic (animal-based) and abiotic (non-living) methods of pollination.
- Animal Pollinators (Zoophily):
- Bees: Colour preferences, flower structure, and nectar guides.
- Moths: Nocturnal pollination, pale fragrant flowers, tubular shapes.
- Flies: Hoverflies and midges, scent attraction, trap mechanisms.
- Birds: Mainly non-UK examples; traits of bird-pollinated flowers.
- Wind Pollination (Anemophily): Flower traits like lack of petals and feathery stigmas.
- Examples include grasses, birch, hazel, and maize.
- Water Pollination (Hydrophily): Surface and submerged pollination strategies.
- Adaptations like mucilaginous pollen.
Photosynthesis and Respiration
The Concept and Importance of Photosynthesis and Respiration for Plant Growth
Photosynthesis
- Definition and purpose: converting light, CO₂, and water into glucose and oxygen
- Location: chloroplasts in green plant cells
- Word equation
- Role in plant growth: glucose for energy, structure, and storage
Respiration
- Definition and purpose: releasing energy from glucose using oxygen
- Location: mitochondria in all cells
- Word equation
- Role in plant growth: energy for life processes, repair, growth, and survival
Interaction Between Photosynthesis and Respiration
- Comparison table: inputs, outputs, timing, and energy flow
- Concept of energy balance between the two processes
Horticultural Relevance
Importance of aerobic respiration and effects of temperature on sugar use
Greenhouse control of environmental factors
Issues in variegated plants and water stress
The Processes of Photosynthesis and Respiration in Plants
Photosynthesis
- Definition and purpose
- Word and chemical equations
- Inputs and outputs
- The main site of photosynthesis and the plant structures involved
- Environmental factors affecting the rate (light, CO₂, water, temperature, nutrients)
- Horticultural importance and examples
Respiration
- Definition and purpose
- Word and chemical equations (aerobic)
- Comparison between aerobic and anaerobic respiration
- Where and when does it occur in the plant
Comparison Table
Side-by-side comparison of photosynthesis vs respiration (location, timing, inputs/outputs, and function)
Movement of Water Through the Plant
The Role of Water in Plants
Why Water Matters
- Introduction to water’s central role in plant survival, growth, and reproduction.
Key Functions of Water in Plants
- Photosynthesis: Water is a raw material in glucose production.
- Nutrient Transport: Movement of minerals through xylem and sugars through phloem.
- Structural Support (Turgor Pressure): Water maintains plant rigidity and shape.
- Temperature Regulation: Cooling effect via transpiration.
- Biochemical Reactions: Solvent for metabolic processes.
- Seed Germination: Triggers enzyme activity and growth initiation.
Summary Table
Quick reference matching each function with the water’s role.
The Processes of Water Uptake and Movement Through the Plant
Key Sections Covered:
Water Uptake by the Roots
- Water enters root hair cells by osmosis.
- Moves from high to low water potential (soil to root).
- Passive process, influenced by soil moisture and structure.
Movement Across the Root to the Xylem
- Water travels inward via three pathways:
- Apoplast (between cells, blocked at the Casparian strip),
- Symplast (through cytoplasm),
- Vacuolar (through vacuoles).
- Casparian strip ensures selective uptake.
Entry into the Xylem
- Water enters dead, hollow xylem vessels.
- Root pressure builds as minerals are actively transported in, drawing water osmotically.
Upward Movement – The Transpiration Stream
- Driven by the Cohesion-Tension Theory:
- Transpiration pull creates suction.
- Cohesion keeps water molecules together.
- Adhesion helps water stick to xylem walls.
Water Movement Through the Leaf
- Water moves into mesophyll cells and evaporates.
- Vapour exits through stomata (transpiration).
- This process cools the plant, moves nutrients, and keeps cells turgid.
The Transpiration Stream and Water Loss From the Leaf
Topics Covered:
- Definition of the Transpiration Stream
Explains how water moves from the roots to the leaves and evaporates via stomata. - Step-by-Step Water Movement
- Water uptake by root hairs (osmosis)
- Apoplast and symplast pathways
- Role of the Casparian strip
- Upward movement through the xylem via the cohesion-tension theory
- Types and Processes of Transpiration
- Stomatal (main route)
- Cuticular and lenticular (minor routes)
- Water evaporation from the mesophyll and diffusion through the stomata
- Factors Affecting Transpiration Rate
Includes light, temperature, humidity, wind, soil moisture, and CO₂ levels - Importance of Transpiration
Covers mineral transport, turgor maintenance, photosynthesis, and cooling
Plant Health
Environmental Conditions
Abiotic Conditions That Can Adversely Affect Plant Health
Summary Coming Soon
Plant Nutrition and Plant Health
The Role of Nutrition in Ensuring Plant Health
Summary Coming Soon
Symptoms of Nutritional Deficiencies
Summary Coming Soon
Impact of Competition on Plant Health
The Benefits of Weeds as Cover Crops, Nutrient Recyclers, Habitats and Food Sources
Summary Coming Soon
The Disadvantages of Weeds, e.g., Competition with Plants for Water, Nutrients, Physical Space, and Sunlight.
Summary Coming Soon
The Role of Weeds as Hosts for Plant Pests and Pathogens
Summary Coming Soon
Legal Control Measures for Weeds, e.g., the Weeds Act, Antisocial Behaviour Orders (Japanese Knotweed).
Summary Coming Soon
Cultural, Physical, Mechanical and Chemical Weed Control Principles
Summary Coming Soon
Negative Environmental Impacts of Weed Control Methods, e.g. Cultivation of Soil, Chemical Control.
Summary Coming Soon
Pests and Pathogens
How Pests and Pathogens are Introduced to a Site
Summary Coming Soon
The Impacts of Pests and Pathogen Presence on Plant Health
Summary Coming Soon
The Control Measures to Prevent and Manage Outbreaks of Pests and Pathogens
Summary Coming Soon
Legalities of Pest Control
Summary Coming Soon
Biosecurity and Plant Passports
Principles and Purposes of Biosecurity
Summary Coming Soon
The Purpose and Use of Biosecurity Policies
Summary Coming Soon
Maintaining Plant Health
The Relationship Between Plant Health Status and Resilience to Pests and Pathogens
Summary Coming Soon
Plant Nutrition
Soil Types and Profiles
The Impact of Soil on Plant Growth
Summary Coming Soon
Horticultural Significance of Soil Loss and Degradation on Plant Growth. Impact of Climate Change
Summary Coming Soon
Concept of Soil Structure
Summary Coming Soon
The Function of Macro- and Micronutrients Within Plants
Summary Coming Soon
Soil-Based Nutrition
Natural Nutrient Cycles, The Fixation of Atmospheric Nitrogen, The Role of Microbial Activity in the Release of Nutrition
Summary Coming Soon
The Role of Soil Micro-Organisms in Making Plant Nutrients Available
Summary Coming Soon
The Importance of The Rhizosphere in Nutrient Uptake
Summary Coming Soon
The Role of Fertilisers in Growing Media
Summary Coming Soon
The Role of Natural Fertiliser Teas
Summary Coming Soon
The Use of Green Manures
Summary Coming Soon
pH and Nutrient Availability
Impact of pH on Nutrient Uptake
Summary Coming Soon
Bulk Constituents for Growing Media
Bulk Constituents, Their Characteristics, and Environmental Footprints
Summary Coming Soon
Historic Use of Peat
Summary Coming Soon
The Removal of Peat in Growing Media
Summary Coming Soon
Plant Specification
Site-Based Criteria
Site Factors That Impact Plant Establishment and Growth
Summary Coming Soon
The Potential Impact of Climate Change on The Above Factors
Summary Coming Soon
Plant-Based Criteria
Impact of Plant Requirements on Selection
Summary Coming Soon
Application of Plant Science to Inform Plant Selection
Summary Coming Soon
The Value of AGMs, Hybrids, Clones and Resistant Hybrids, etc
Plant Specifications
Factors When Ordering Plant Materials
Summary Coming Soon
Receiving Plant Material on Site
Processes for Receiving Plant Material on Site
Summary Coming Soon
Indicators of Plant Quality Issues
Summary Coming Soon
Planting and Post-Planting Care
The Process of Planting
Summary Coming Soon
Maintaining New Plantings
Purpose, Timing and Components of Maintenance Tasks for the First 12 Months After Planting
Summary Coming Soon
The Reasons For Recording Failure Rates
Summary Coming Soon
Unit 2
Plant Science II
Leaf Adaptations
Leaf Adaptations
Summary Coming Soon
The Potential of Leaves for Propagation (Totipotency)
Stem Adaptations
Stem Adaptations
Summary Coming Soon
The Potential of Stems For Propagation (Totipotency)
Summary Coming Soon
Root Adaptations
Root Adaptations
Summary Coming Soon
The Potential of Roots for Propagation (Totipotency)
Summary Coming Soon
Flower Adaptations
Summary Coming Soon
Seed Adaptations
Summary Coming Soon
Growth Habit Adaptations
Summary Coming Soon
Planting Styles
Historical Contexts
Key Design Characteristics of Historical Landscapes and Gardens Most Relevant to the Heritage Sector
Summary Coming Soon
Formal Planting
Features of Formal Planting Styles
Summary Coming Soon
Informal Planting
The Features of Informal Plantings and Their Design Function
Summary Coming Soon
Planting Associations
Summary Coming Soon
Plant Uses
Uses of Plants Within a Garden
Summary Coming Soon
Implications of Poor Plant Selection for Purpose and Function in Design
Summary Coming Soon
Edible Landscapes
Planting Styles Suitable for Edible Landscapes Including Herbs, Fruit and Vegetables
Summary Coming Soon
The Principles of Growing Systems, Including Traditional, Organic, and Biodynamic
Potagers, Containers and Accessible Edibles
Summary Coming Soon
Short-Term Plantings
Characteristics of Plant Species Suitable for Short-Term Plant Displays, e.g. Traditional Bedding, Mazes, Annual Meadows
Summary Coming Soon
Plants Suitable for Seasonal Display
Summary Coming Soon
The Positive and Negative Environmental Impact of Seasonal Displays
Summary Coming Soon
Horticulture and Society
Wellbeing
The Social Benefits of Gardening
Summary Coming Soon
The Social Benefits of Urban Greening, Allotments, and Parks and Gardens
Summary Coming Soon
Environment
Positive Impacts of Horticulture on The Environment
Summary Coming Soon
Negative Impacts of Horticulture
Summary Coming Soon
The Principles and Implications of Climate Change
Summary Coming Soon
Environmental Benefits of Different Garden Spaces
Summary Coming Soon
Economy
UK Horticultural Sectors
Summary Coming Soon
Community
Types of Community Horticultral Projects and Their Impact
Summary Coming Soon
Biodiversity
Plants and Biodiversity
The Basic Principles of a Food Chain/Web Including Producers Plus Primary, Secondary and Tertiary Consumers
Summary Coming Soon
The Relationship Between Plant Diversity and Primary and Secondary Consumers in a Habitat e.g. Ragwort and Cinnabar Moth
Summary Coming Soon
The Importance of Re-evaluating Concepts e.g. Considering Pests/Weeds From a Biodiversity Perspective
Smmary Coming Soon
The Role of Botanical Gardens in Conservation and Education
Summary Coming Soon
Impacts of Climate Change
The Impact of Climate Change on Plants
Summary Coming Soon
Creating Habitats
Importance of Habitats in Horticultural Sites
Summary Coming Soon
Citizen Science and Species Surveys
Wildlife Present in Gardens and its Requirements
Summary Coming Soon
The Role of Citizen Science Projects to Identify Species’ Population Trends e.g. RSPB Big Garden Bird Watch, Butterfly Conservation
Summary Coming Soon
Biodiversity Action Plans
Summary Coming Soon