Tuesday Lecture – Ornamental Plants
Reading: Textbook, Chapter 17
Quiz
Quiz
1. Describe a factor that could result in a plant having a
leaf that has a coloration other than solid green.
2. Describe a feature of the UTIA Gardens that you
particularly liked.
Naming Ornamentals
Difficulties introduced by the nature of ornamentals:
often hybrids
- many are sterile, propagated vegetatively
- mutants with striking features – propagated vegetatively to
retain features
- marketing
International Code of Horticultural Nomenclature – sets of rules
governing assignment of cultivar names
 Some widely grown plants may have a registry of cultivar
names
Naming Ornamentals
Difficulties introduced by the nature of ornamentals:
- often hybrids
- many are sterile, propagated vegetatively
- mutants with striking features – propagated vegetatively to
retain features
- marketing
International Code of Horticultural Nomenclature – sets of rules
governing assignment of cultivar names
 Some widely grown plants may have a registry of cultivar
names
Naming Ornamentals
Difficulties introduced by the nature of ornamentals:
- often hybrids
- many are sterile, propagated vegetatively
- mutants with striking features – propagated vegetatively to
retain features
- marketing
International Code of Horticultural Nomenclature – sets of rules
governing assignment of cultivar names
 Some widely grown plants may have a registry of cultivar
names
Naming Ornamentals
Difficulties introduced by the nature of ornamentals:
- often hybrids
- many are sterile, propagated vegetatively
- mutants with striking features – propagated vegetatively to
retain features
-marketing
International Code of Horticultural Nomenclature – sets of rules
governing assignment of cultivar names
 Some widely grown plants may have a registry of cultivar
names
Naming Ornamentals
Difficulties introduced by the nature of ornamentals:
- often hybrids
- many are sterile, propagated vegetatively
- mutants with striking features – propagated vegetatively to
retain features
- marketing
International Code of Horticultural Nomenclature – sets of rules
governing assignment of cultivar names
 Some widely grown plants may have a registry of cultivar
names
Naming Ornamentals
Difficulties introduced by the nature of ornamentals:
- often hybrids
- many are sterile, propagated vegetatively
- mutants with striking features – propagated vegetatively to
retain features
- marketing
International Code of Horticultural Nomenclature – sets of rules
governing assignment of cultivar names
 Some widely grown plants may have a registry of cultivar
names
Cultivar Names
2. Variation within cultivated plants
- “variety” – widely (and still) used
- cultivar (cultivated variety)
Used to denote an assemblage of cultivated plants that is
clearly distinguished by some character(s) and that following
reproduction retains its distinguishing character(s)
Cultivar name is written in any language except for Latin
Cultivar name can be combined with a generic, specific, or
common name:
Citrullus cv. Crimson Sweet;
watermelon cv. Crimson Sweet;
Citrullus lanatus cv. Crimson Sweet
Types of Ornamentals
1. Nursery Crops – planted outside
- trees/shrubs; turf; ground covers; bedding plants
Types of Ornamentals
1. Nursery Crops – planted outside
- trees/shrubs; turf; ground covers; bedding plants
2. Florist Crops – grown for cut flowers or foliage
- increased worldwide: $12.5 billion (1985)  $25 billion (2009)
Types of Ornamentals
1. Nursery Crops – planted outside
- trees/shrubs; turf; ground covers; bedding plants
2. Florist Crops – grown for cut flowers or foliage
- increased worldwide: $12.5 billion (1985)  $25 billion (2009)
US – dipped from 4.2 billion (2007) to 3.8 billion (2009)
Types of Ornamentals
1. Nursery Crops – planted outside
- trees/shrubs; turf; ground covers; bedding plants
2. Florist Crops – grown for cut flowers or foliage
- increased worldwide: $12.5 billion (1985)  $25 billion (2009)
3. Houseplants – sold for growing indoors
- plants must survive in harsh environment
Asteraceae – The Ornamental Family
- Ageratum
- Aster
- Black-eyed Susan
- Cornflower
- Dahlia
- Daisy
- Marigold
- Chrysanthemum (Dendranthemum)
- Sunflower
- Zinnia
Topped by a Head
Topped by a Head
Variations on a Theme
Dandelion – all rays
Variations on a Theme
Dandelion – all rays
Pussytoes – all disk
Variations on a Theme
Dandelion – all rays
Cornflower – All
Disk/outer ones larger
Pussytoes – all disk
“Doubled” Heads
Single (“Old-Fashioned”) Zinnia
“Doubled” Heads
Single (“Old-Fashioned”) Zinnia
Double Zinnia
Another Double
Marigold – Tagetes - native to Mexico
Single Marigold
Double Marigold
Daisy – Inspiration for “Big Orange”
Daisy – Inspiration for “Big Orange”
UT Uniform
Color – traces
origin to center
of daisy heads
Daisy – Inspiration for “Big Orange”
UT Uniform
Color – traces
origin to center
of daisy heads
Shasta Daisy –
tetraploid selection
of Luther Burbank
Polyploidy – Breeding Tool
Polyploidy: >2 sets of
chromosomes
1. Determinate organs
will be larger
2. Stabilizes (and
sometimes makes
fertile) hybrids
3. Odd polyploids 
often sterile:
- no messy seeds
- no need to
“deadhead”
Daylilies – Hemerocallis fulva
Diploid
Tetraploid
Flowers - Variations
Showy structure is not part of flower
bract
dogwood
poinsettia
More Flower Variations
More Flower Variations
“doubled” flowers – stamen primordia  petals
Pink
Carnation
Araceae – the Houseplant Family
Many Aroids – tropical epiphytes –
habitat similar to house/apartment
Spathiphyllum – the Mall Plant
Note: inflorescence is spathe + spadix
Amorphophallus – a Giant Aroid
1.37 m tall
Geneticist Huge de Vries, one
of the rediscoverers of
Mendel’s Laws, provides scale
for an inflorescence of the
“Voodoo Plant”
Amorphophallus titanum
Amorphophallus – a Giant Aroid
1.37 m tall
An Aroid
Gallery
How Dumb Cane Got Its Name
How Dumb Cane Got Its Name
Calcium oxalate –
characteristic crystalline
inclusions (raphides) in
Araceae  extreme
irritation of mucous
membranes
Can lead to fatal swelling
of passages to lungs
Commonly Ingested Aroids
From List of “Top 20 Ingested Plants” Reported to Poison Control
Centers in U.S.:
2. Philodendron
4. Spathiphyllum
6. Dieffenbachia
10. Epipremnum (Pothos)
Treatment: Symptomatic and Supportive – remove residue from
mouth; provide liquids; monitor breathing (major danger is
suffocation is swelling is severe)
Invasive Plants – The Dark Side
of Ornamentals
Invasive Plants = “Biological Pollution”
“Rule of 10’s”:
Invasive Plants – The Dark Side
of Ornamentals
Invasive Plants = “Biological Pollution”
“Rule of 10’s”:
For every 10 plants introduced, 1 will become established
Invasive Plants – The Dark Side
of Ornamentals
Invasive Plants = “Biological Pollution”
“Rule of 10’s”:
For every 10 plants introduced, 1 will become established
For every 10 established, 1 will become invasive
1 in 100 introductions becomes invasive
Invasive Plants – The Dark Side
of Ornamentals
Invasive Plants = “Biological Pollution”
“Rule of 10’s”:
For every 10 plants introduced, 1 will become established
For every 10 established, 1 will become invasive
1 in 100 introductions becomes invasive
Often a long lag time, introduction  problematic invader
“First it sleeps, then it creeps, then it leaps …”
Invasive Plants – The Dark Side
of Ornamentals
Invasive Plants = “Biological Pollution”
“Rule of 10’s”:
For every 10 plants introduced, 1 will become established
For every 10 established, 1 will become invasive
1 in 100 introductions becomes invasive
Often a long lag time, introduction  problematic invader
How to Predict Invasiveness?
- only clear guide, if invasive in other areas
Dandelion - Invader
Taraxacum officinale (“of the shops”)
Dandelion - Invader
Taraxacum officinale (“of the shops”)
Dandelion (“dents du lion” = lion’s
tooth, from leaves)
Dandelion - Invader
Taraxacum officinale (“of the shops”)
Dandelion (“dents du lion” = lion’s
tooth, from leaves)
Asteraceae – all ray flowers
Introduced by Pilgrims – used as
spring potherb
Dandelion - Invader
Taraxacum officinale (“of the shops”)
Dandelion (“dents du lion” = lion’s
tooth, from leaves)
Asteraceae – all ray flowers
Introduced by Pilgrims – used as
spring potherb
Flowers – produce abundant nectar 
sugar source to produce wine
Dandelion - Invader
Taraxacum officinale (“of the shops”)
Dandelion (“dents du lion” = lion’s
tooth, from leaves)
Asteraceae – all ray flowers
Introduced by Pilgrims – used as
spring potherb
Flowers – produce abundant nectar 
sugar source to produce wine
Apomictic – seeds produced without
fertilization  clones of parent
Will mature its seed even if uprooted
Tennessee Invaders
TN-EPPC (Tennessee Exotic Pest Plant Council) – List
Trees: Mimosa (Albizzia); Princess Tree (Paulownia); Tree-ofHeaven (Ailanthus)
Shrubs: Autumn Olive (Eleagnus); Bush Honeysuckles (Lonicera);
Japanese Barberry (Berberis); Multiflora Rose (Rosa); Privet
(Ligustrum)
Herbs: Purple loosestrife (Lythrum); others
Vines: Euonymus; Japanese honeysuckle (Lonicera); Japanese
wisteria; Kudzu (Peuraria); Oriental Bittersweet (Celastrus)
Native Plants – A Great Resource
Answer to Invaders = use native plants
See Box 17.2, p. 429 Wildscaping
Opportunity: provide plants for revegetation, environmental
restoration projects
Thursday, Genetically Modified (GM) Plants