Horticulture II (Plant Knowledge)

Become a Plant Expert: Learning to identify plants is as important as knowing how to grow them. Identify shrubs, trees, plants; learn the taxonomy of plant identification and how to grow different plants via online study.

Course CodeBHT102
Fee CodeS2
Duration (approx)100 hours
QualificationStatement of Attainment

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Learn to Identify Plants Systematically and Scientifically

  • Plant identification is arguably the most important skill for any gardener, landscaper or professional horticulturist
  • There are thousands of different garden plant cultivars that horticulturists may need to work with throughout their career.
  • Every different cultivar looks different, and has different growth requirements.
  • It isn't as hard as you might think to identify all these plants, once you get to know the system!

There is a system to how plants are identified!    Once you understand this system, and it becomes second nature to you; your ability to identify a plant and remember its name will become much easier.

Example:   Plants that are in the mint family have a square stem, oil glands in the leaf, leaves arranged opposite on the stem, and a flower that is two lipped. If you can look at a plant and recognise characteristics like this, you may then place it in the correct family. Once you have a "hook" (being the family) to hang a plant on; your brain will be more likely to remember it. Not only that, but most families share a whole range of characteristics. Once I know the family of a plant, I can make reasonable assumptions about it's susceptibility or resistance to certain problems, and how to grow it.

Your measure and success as a horticulturist may depend more than anything else;
on your level of plant knowledge.

Lesson Structure

There are 10 lessons in this course:

  1. The Groups of Plants ‑ setting a framework for the whole subject. Learn to identify plants from a wide range of taxonomic and cultural groups, using a range of different techniques.
  2. Use of Plants ‑ plant selection, soils.
  3. Australian Native Plants -The growing of native shrubs and trees, including the selection, culture and use of different species.
  4. Exotic Ornamental Plants -Techniques for the growing of exotic ornamental shrubs and trees, including the selection, culture and use of different species.
  5. Indoor & Tropical Plants -Growing indoor plants, including selection, culture and use of different varieties
  6. Bedding Plants -Bedding plants...growing, selection, culture and use of different varieties.
  7. Vegetables -Techniques for the growing of edible crop plants, including selection, culture and use of vegetables, fruit, berries and nuts (Part A).
  8. Fruits, Nuts & Berries
  9. Herbs
  10. Alternative Growing Techniques ‑ hydroponics, container growing, terrariums. Determine appropriate applications for a range of alternative growing methods

Each lesson culminates in an assignment which is submitted to the school, marked by the school's tutors and returned to you with any relevant suggestions, comments, and if necessary, extra reading.


  • Identify plants from a wide range of taxonomic and cultural groups, using a range of different techniques.
  • Determine techniques for the growing of native shrubs and trees, including the selection, culture and use of different species.
  • Determine techniques for the growing of exotic ornamental shrubs and trees, including the selection, culture and use of different species.
  • Determine techniques for the growing of indoor plants, including selection, culture and use of different varieties.
  • Determine techniques for the growing of bedding plants, including selection, culture and use of different varieties.
  • Develop techniques for the growing of edible crop plants, including selection, culture and use of vegetables, fruit, berries and nuts.
  • Determine appropriate applications for a range of alternative growing methods.

Do You Understand How Plants are Named?



Linnaeus (1707‑1778) was a Swedish botanist largely responsible for stabilising the binomial system (ie. using two names or two words to name one plant). He was also responsible for stabilising some of the other basic principles of nomenclature. However it wasn't until 1867, at the first International Botanical Congress, that the first set of rules were officially adopted by the botanical world. Deficiencies in this code led to the establishment of a number of other sets of rules. A compromise between the existing codes was adopted in 1930 and published as the 3rd edition of the International Rules of Botanical Nomenclature. More recent editions are basically modifications of this code.



Published in 1966, this most recent edition of the code contains an enormous amount of detail which is only of any real interest to the specialist, however, some of the information from the code outlined below is valuable in helping us understand better the way in which plants are classified.


Ranks of Taxa

The code indicates the ranks (ie. levels of classification) of taxa which can be used, and specifies the order in which they must be placed. In all, there are 23 ranks listed and provision is made for supplementary ranks. It isn't necessary to use all ranks for a particular organism. In day to day use, the genus and species are the two ranks which are commonly used. The endings of names of taxa of some ranks are standardised (ie. names of the rank of family end in `aceae', .eg. Rosaceae).

Commonly used ranks are listed below, in order and with examples:

Division ‑ Spermophyta

Class ‑ Angiospermae

Order ‑ Rosales

Family ‑ Rosaceae

Genus ‑ Prunus

Species ‑ persieae

Variety ‑ versicolour


Principle of Priority

This provision means that a plant can bear only one legitimate name and two different plants cannot be called by the same name. The legitimate name of a plant is the one published first, in or after 1753, in accordance with the code.

a) Valid Publication

To be validly published the name must be published in a suitable book or journal accompanied by a description or diagnosis of its rank, stating in detail the characteristics which distinguish it from others.

b) The Type Method

For species categories or anything below that level of classification, a specimen must be nominated as the type (an example of that classification) and deposited in a herbarium (herbariums store collections of pressed plants as a reference point; usually government sponsored and often associated with botanical gardens). The type provides a permanent record of the kind of plant which is associated with that particular classification.

c) Aim of the Principle of Priority

Aim of the principle is to stabilise nomenclature when two or more names are inadvertently coined for the same taxon (ie. for the same type of plant). The one which was published first takes that name and the other must be renamed.

d) Exceptions to the Principle of Priority

Occasionally even if published validly, names have to be rejected in certain prescribed circumstances eg. if the same name is published for two different genera or families.

Sometimes names are `conserved' (ie. remain valid) though they were not the first published of two contending names. This is usually because they have been more commonly used than the earlier name (eg. Melaleuca (1767) instead of Cajaputi (1763).


Plant and Animal Nomenclature

Plant nomenclature is independent of animal nomenclature. It does not matter if the name of a plant is the same as an animal, although it is better to be avoided if possible.

Choice, Construction and Spelling of Names

  • Botanical names are Latin and are treated as such, the code being very precise on matters of grammar.
  • Names of orders and sub orders are based on the stem of the name of a family from that particular order or sub order with the ending "‑ales" for orders and "‑ineae" for the sub orders. There are only a few exceptions eg. Order Proteales (from family Proteaceae). Usually the names of families, sub families, tribes and sub tribes are formed by adding a specified suffix to the stem.
  • The name of a genus is a noun (or sometimes an adjective) which can usually be taken from any source.
  • The name of a species is binomial, ie. it consists of two words, the first being the generic name and the second a specific name describing a particular characteristic about the species (eg. spinosa ‑ spiny; paludosus ‑ growing in swampy places; citriodora ‑ lemon scented; pendula ‑ weeping; rubra ‑ red).
  • The main categories or divisions below species are:
    • subspecies (which are divided into varieties)
    • varieties (which are divided into forms)

Changes in Names

Provided there is good reason, it is possible to change names. For example, if a genus is considered to be in the wrong family or a species in the wrong genus it can be transferred to the correct one. Sometimes it might be decided that one genus should be divided to make two or three genera. The code governs the way in which such things happen (eg. if a genus is split then the original name must be retained for at least one of the new genera).


Nomenclature of Hybrids

The names of hybrids (different species which have cross bred) are governed by the same rules as the names of other taxa. The hybrid is designated by the use of a multiplication sign preceding a given name (eg. Salix x capreola which is a hybrid of Salix aurita and Salix caprea) or by a formula (eg. Salix aurita x caprea).



( ) Indicates the original authority for a name. For example, Medicago arabica (L) Huds. This means it was originally named by Linnaeas but the name was changed by Hudson later. 

nom. cons. Indicates the name conserved against some earlier published name. 

nov. Indicates new taxon. 

syn. Indicates a synonymous name 

nov. syn. Used when a name is first reduced to synonymy. 

cv Indicates cultivar name. 



Colour charts have been used to standardise the descriptions on plants. As personal opinion and biases may result in inaccuracies, there is a need for uniformity in describing plants around the world. Two accepted charts exist and are widely used. These are the Royal Horticultural Society (RHS) and Exotica.

Colour descriptions should be used when describing leaves, flower parts, stems and any other item worth noting.

The advantage of the colour charts in book such as Exotica is that as you read about the plant you can refer to the colour charts to get a better idea of the plant.

There are other ways that plants are classified apart from the scientific system; particularly when you are dealing with some of the more popular genera. For example:

Roses are Classified by Rose Enthusiasts as follows

Modern roses are broadly divided into the following groups:

BUSH ROSES: These grow into an upright bush up to 2 m tall. The three main types are:

  • Hybrid Teas (give the biggest and best flowers)
  • Floribundas (greater quantity but less quality in the flowers)
  • Grandifloras

Some old world species grow as bush types also, but these are less common.

STANDARD ROSES: These are budded into long, single, upright stems giving the effect of the bush sitting high in the air on a pole. Standard roses are anything from 1 m to 3 m tall.

RAMBLERS: These are very vigorous, usually untidy growers which make a lot of new growth from the base. They have large quantities of small flowers in bunches.

CLIMBING ROSES: These have fewer basal shoots, larger flowers (either individually or in small clusters), and solid, thick climbing stems.

MINIATURE ROSES: Growing from 1 to 2 feet tall, stems are thinner and flowers are smaller than normal bush roses. In effect they appear as scaled down versions of the floribundas or hybrid teas.

There are species and varieties of the genus "Rosa" which can be grown in almost any climate, provided the right type is chosen for the particular situation. Most species tend to adapt better to cooler climates than to warmer climates.


What You Will Get from this Course

  • Plant knowledge is the foundation of all good horticulture
  • People who can identify plants impress employers and clients
  • Graduates know what to look for when examining plants; how to work out what family a plant belongs to, and ways of narrowing a plant down to determine genus and species after that.
  • Plants within a family or genus share common management requirements: learn identification and you have a foundation for managing plants.

Student Comment:  "I have found the course to be interesting and challenging, with great learning materials that really make you research the industry and get involved. It has been a great way to study because it has allowed me to work in the industry and study at the same time. I have found the online resources to be fantastic, the tutors feedback constructive and the fact that assignments can be submitted online makes the process so easy."  Tom Wood, Australia 


Different pathways people follow to become an expert plantsman/woman. Whatever path you follow though; you do need to learn the same fundamental things about plant identification. Those things can be learnt in this course.

  • Some people start out as a gardener or labourer, learning on the job. This can be a great start; but you still need a grounding in the theory to underpin what you encounter at work. Without that, you risk lacking a complete and accurate understanding of the plants you encounter. This course can make all the difference, making what is learnt at work far more valuable.
  • Many people begin as a home gardener; developing a passion for horticulture, and in turn a desire to develop a career. Passion and experience are essential and help make a career successful. Without some study as well, the potential for success will never be as great though.
  • Some begin by studying plants: maybe horticulture, maybe botanical science. 

Once you know how to identify plants, you then have skill and knowledge that is extremely valuable; to nurserymen and landscapers, parks managers and environmental officers. Virtually any career that deals with plants will be advanced by studying this course.

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Marie Beermann

Marie has more than 10 years experience in horticulture and education in both Australia and Germany. Marie's qualifications include B. Sc., M. Sc. Hort., Dip. Bus., Cert. Ldscp.
John Mason

Parks Manager, Nurseryman, Landscape Designer, Garden Writer and Consultant. Over 40 years experience; working in Victoria, Queensland and the UK. He is one of the most widely published garden writers in the world.
Jacinda Cole

B.Sc., Cert.Garden Design. Landscape Designer, Operations Manager, Consultant, Garden Writer. He was operations manager for a highly reputable British Landscape firm (The Chelsea Gardener) before starting up his own landscaping firm. He spent three year
Robert James

B.App. Sc. (Horticulture), Dip.Ag., M.Sc., Grad Dip.Mgt. Over 50 years experience that includes, Nursery Manager Brisbane City Councoil, Grounds Manager (University of Qld), Lecturer Qld Agricultural College, Propagator/Nurseryman at Aspley Nursery, Hort