Plant Identification

Amy Jo Detweiler, Jan McNeilan, Gail Gredler

Horticulture Department

List 6 reasons why plant identification is important

History of Plant Nomenclature (naming of organisms)

• herbs• undershrubs• shrubs• trees

• Dates back to 200 B.C. to China and Egypt

• Greeks and Romans classified plants into 4 groups

Listed plants using Latin terms, e.g. carnation would be

Another example:

Oriental ivy-leaved maple

Binomial System of Nomenclature

• system developed by Carl Von Linne or Linnaeus in the 1700’s used to methodically classify and name the whole of the natural world

• Species Plantarum (1753)• system still in use today

Botanical nomenclature

• language is mainly Latin with Greek and some other languages

• these are “dead languages” whose words and meanings will likely change little over time

The names of plants

• The scientific name for a plant consists of two words:

1. Genus or generic name2. specific epithet species

e.g.Quercus rubra

Back to our example:

Acer orientalis hederae foliounder the binomial system would be…

Carpinus caroliniana

Reasons not to use common names

Nymphaea albaEuropean White Waterlily

•By using the binomial system of nomenclature, plant names are the same in all languages!

•Every plant has a “first and last name” where the last name is written first.

Binomial Nomenclatureclarifies plant i.d.

• Deodar cedar

• Atlas cedar

Plant Classification

• There are over 1 million botanically different plants in existence named by the binomial system of nomenclature.

• Modified by the International Congresses in Plant Taxonomy

Plant Classification

• Kingdom• Division• Class• Order• Family• Genus• Species

Gardeners use these 3

Which part of the plant is used for classification?

Plant Classification•Nearly all classifications are based on the parts of the and the

_________

____.

Family• a group of plants with similar

characteristics especially flowers, fruits, and seeds, the reproductive structures are used for distinction.

• The size of a family varies from 1 to 100+

e.g Ginkgoaceae has one genus Ginkgo biloba

Rosaceae has 100 genera (Malus, Spiraea, Rosa)

Genus(plural genera)

• a group of plants which is a closely related, definable group of plants exhibiting similar characteristics (flowers, fruit, stems, leaves, or roots) and genetic affinity

The genus is usually a noun, capitalized and can serve to describe one of the following:

• a plants appearance-Hemerocallis (day and beauty)

• supposed medicinal qualities- Pulmonaria (lungwort)

• resemblance to body parts-Hepatica (liver)

• honors a person by using their name – Kalmia (Peter Kalm)

Specific epithet

• the second word in a scientific plant name, not capitalized and usually an adjective used to describe size, color, leaf shape, growth habit, origin of the plant or to commemorate a person.

The specific epithet can give us

hints plant about the plant: • Cotoneaster horizontalis• Coreopsis gigantea• Clerodendrum thomsoniae• Godetia grandiflora• Cistus x purpureus• Chionanthus virginicus

Species• the basis of the binomial system of

nomenclature• a difficult word to define, a population of

individuals within a genus that are capable _________________________________________________________

Writing plant names correctly

• scientific names should always be underlined or in italics

• the genus is capitalized, the specific epithet is not

• the name is only complete if it is followed by the name of the person who first described or named it

For example: Red OakQuercus rubra Linnaeus

orQuercus rubra L.

Quercus rubra or Quercus rubra

Plant species can be divided more specifically into:

•a cultivar•variety•hybrid• forma

Cultivar• “Cultivated variety” or horticultural

variety• plants within a species that have

been selected especially for a particular characteristic and are propagated, usually asexually to continue this trait(growth habit, flower, fruitless)

Cultivar names written in plain text, capitalized and

set off by single quotes, e.g.Viburnum opulus ‘Roseum’

Viburnum opulus cv. Roseum

Variety • botanical or wild variety• a group of plants intermediate

between species and forma and usually associated with inheritable differences. They are recognized as distinct populations breeding true to type

Variety names• written in lowercase and italicized or

underlined• e.g. Pinus contorta var. contorta

Shore Pine• Pinus contorta var. latifolia

Lodgepole Pine

Hybrid• two closely related but distinct

species will be interbreed to form a hybrid

• are often sterile and produce no seed or fruit

Hybrid names• written in lowercase and italicized

or underlined• an “x” is placed between the

genus and hybrid epithet

Platanus occidentalis crossed with Platanus orientalis

Plantanus x acerifolia

Plant name exercise• What is the name of the plant that

produces maple syrup?

Integrated Approach to Plant Identification

• Visual inspection of plant characteristics

• Photographic references• Plant classification keys• Expert advice

Collect information about what you see:

Herbaceous, conifer, broadleaved evergreen, deciduous?

Collect information about what you see:

What is the overall form of the plant?

Collect information about what you see:

What are the characteristics of individual plant parts?

Leaf type-simple leaf

Leaf type-pinnately compound

Leaf type

Leaf type

Leaf type

Leaf type

Leaf type

Leaf Arrangement

Leaf Arrangement

Leaf Arrangement

Leaf Arrangement

Types of Venation

Types of Venation

Types of Venation

Types of Venation

Leaf margins

Stem and Bud

Other i.d.features - buds

Other i.d.features-bark

Other i.d.features - spines

Other i.d.features -fruit

Other i.d.features - fruit

Other i.d.features – flower & fruit

Conifer I.D.: Cones

Other i.d.features - flowers

Using dichotomous keys to identify plants

A.A.

B.B.

BB.BB.

C.C.

D.D.

DD.DD.

CC.CC.

AA.AA.

E.E.

EE.EE.

F.F.

FF.FF.

G.G.

H.H.

A dichotomous key offers users a choice between two characters. By making a series of choices between two characters, a correct I.D. is made.

An example for shoesA. leather

B. velcro closures EZBB. shoe laces

C. colored leatherD. red Zippy DD. blue Snazzy

CC. white leather

AA. canvasE. velcro closuresEE. shoe laces

F. low top KedsFF. high top

Converse

Example of dichotomous keyA. Leaves needle-like

B. Needles clusteredC. 2-5 needles/cluster PineCC. >10 needles/cluster

BB. Needles not clusteredD. Pegs on twigs E. Square, sharp needles Spruce EE. Round, blunt needles HemlockDD. No pegs on twigs F. Large pointed buds Douglas-fir FF. Buds round, clustered True fir

AA. Leaves flattened and scale-likeG. All leaves short and sharp Giant SequoiaGG. Some leaves not sharp

Needles are soft

• Needles longer than ½”

• No pegs on twigs

flower and fruit

• leaf edges not smooth

• leaf not thick and leathery

• fruit is nutlike and dry

More resources

Landscape PlantsImages, Identification, and InformationVolume 1 Copyright, Oregon State University, 1999-2004

http://oregonstate.edu/dept/ldplants

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