RHS Level 2 Certificate

Year 1 Week 2

Plant names and Plant Life Cycles

Learning Objectives

Plant taxonomy (2)

State the reasons why a universal system of plant names is important.

Describe the use of the terms ‘genus’, ‘species, and ‘cultivar’. The construction of hybrid names.

Plant life cycles Define the terms: ‘annual’, ‘ephemeral’, ‘biennial’ and ‘perennial’. Define the terms: ‘tender’, ‘half-hardy’, and ‘hardy’ in relation to

annuals. Define the terms: ‘tender’, ‘half-hardy’, ‘hardy’, ‘herbaceous’ and

‘woody’ in relation to perennials. State the meaning of the terms: ‘evergreen’, ‘semi-evergreen’ and

‘deciduous’. Describe what is meant by the terms: ‘juvenility’, ‘maturity’ and

‘senescence’ in the development cycle of a plant and state their horticultural significance

Botanical Names

Why Latin? A common language that allows clear identification of individual species.

Binomial system – Genus and Species. Conventions – Genus and species names written in

italics. Cultivar names in roman characters (normal) and in single quotes.

Papaver [genus] orientale [species] ‘Patty’s Plum’ [cultivar]

Hybrids are crosses between genera or species. Species hybrids indicated by a X in the middle of the name, bi-generic hybrids by a X at the start.

Answers to review sheet

1. Digitalis purpurea – both genus and species names should be in italics (underlined in handwriting).

2. Fagus sylvatica purpurea – correct3. Rosa filipes ‘Kiftsgate’ – capital for genus,

cultivar in roman characters and quotes.4. Astilbe x arendisii – x not +5. x Osmaria burkwoodii – bi-generic hybrid6. Clematis x jackmanii – species hybrid so

the x is between the names

Plant life cycles

Duration of life – annuals, biennials, perennials and ephemeral plants

Sensitivity to conditions – hardy, half hardy and tender.

Leaf replacement – deciduous, evergreen and semi-evergreen.

Over-wintering habit – perennials only. Herbaceous – top growth dies back in winter; woody – top growth persists as a woody structure over winter.

From germination to maturity

Juvenility – plant or growth not able to flower or bear fruit\seeds.

Maturity – plant or growth fully developed and able to flower and bear fruit\seeds.

Senescence – slow tissue death, the death of the plant or part of the plant.

Parts of each plant may be at different stages of this cycle at the same time!! For example, the autumn leaf is senescent but the tree on which it grows may be juvenile.

Why does the development stage matter?

Propagation method – juvenile plants will not set seed; mature growth will not make good material for cuttings.

Appearance – juvenile and mature plants\growth may look very different. E.g. Eucalyptus gunnii.

Planning planting – awareness of life cycle and its duration allows succession to be planned. Juvenile plants will not flower – so this affects planting times for ornamental annuals for example.

Question: how to keep your Eucalyptus gunnii looking youthful?

Like this Not like this

Prune it back to a couple of buds from the base every couple of years – known as coppicing.

Learning Outcomes

Plant taxonomy (2) State the reasons why a universal system of plant names is important. Describe the use of the terms ‘genus’, ‘species, and ‘cultivar’. The

construction of hybrid names. Plant life cycles Define the terms: ‘annual’, ‘ephemeral’, ‘biennial’ and ‘perennial’. Define the terms: ‘tender’, ‘half-hardy’, and ‘hardy’ in relation to

annuals. Define the terms: ‘tender’, ‘half-hardy’, ‘hardy’, ‘herbaceous’ and

‘woody’ in relation to perennials. State the meaning of the terms: ‘evergreen’, ‘semi-evergreen’ and

‘deciduous’. Describe what is meant by the terms: ‘juvenility’, ‘maturity’ and

‘senescence’ in the development cycle of a plant and state their horticultural significance