botanical names and life cycles

1. RHS Level 2 Certificate
Year 1 Week 2
Plant names and Plant
Life Cycles

2. 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

3. Botanical Names
 Why Latin? A common language that allows
clear identification of individual species.
 Stable names – do not change with fashion,
regional variations or language. May change
to reflect scientific understanding.
 Unique names – unlike common names,
each species has its own unique botanical
name.
 Can give information about place of origin,
appearance or use.

4. Binomial System
 Binomial system – Genus and species.
 Conventions – Genus and species names written in
italics. Convention is to underline handwritten names to
indicate italics where necessary.
 Cultivar names in roman characters (normal) and in
single quotes.
 Genus name has a capital, species is all lower case.
 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.

5. Cultivar names
 Cultivate + variety = cultivar. Man made
stable variations in species.
 Cultivar names are in Roman type and in the
language of the country of origin (usually –
some very old cultivars may have ‘latinised’
names ) and in quotes.
 Varieties are naturally occurring, stable,
variations on species. Their names are in
italics, e.g. Dicentra spectabilis alba (a white
variety of Bleeding Heart)

6. Answers to review sheet
1. Digitalis purpurea – both genus and species
names should be in italics (underlined in
handwriting).
2. Fagus sylvatica purpurea – correct
3. Rosa filipes ‘Kiftsgate’ – capital for genus,
cultivar in roman characters and quotes.
4. Astilbe x arendisii – x not +
5. x Osmaria burkwoodii – bi-generic hybrid
6. Clematis x jackmanii – species hybrid so
the x is between the names

7. 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.

8. From germination to maturity
 Juvenility – plant or growth not able to flower
or bear fruitseeds.
 Maturity – plant or growth fully developed
and able to flower and bear fruitseeds.
 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.

9. Why does the development stage
matter?
 Propagation method – juvenile plants cannot set
seed; mature growth will not make good material
for cuttings.
 Appearance – juvenile and mature plantsgrowth
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.

10. 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.

11. 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