Plant taxonomy is the grouping of plants based on their presumed relationships.

Nomenclature is from the Greek Latin which means nom a name and clature to classify. So literally it means to give something a name.

Common names are confusing, localized and are often superficial.

Theophrastus is known as the Father of Botany as he began classifying plants 2400 years ago. Many plants still carry the names he gave them today like Dacus and Nacissus.

“Pliny the Elder” A Roman who tried to record “Everything known about the world. He did not develop any type of system. 

Scientific names:

Sally Stephens described it very adequately when she wrote, ”We tend to classify things. Our socks go in the sock’s drawer and our shirts hang together in the wardrobe separate from our dresses or trousers. Spoons probably all nestle in a compartment beside the forks which lie separately from the knives. Those big clunky kitchen utensils are probably less sorted in a big drawer where we can grab them when needed – but they still have been classified by their use in the kitchen. You certainly wouldn’t put them in the dining room sideboard with the fine table linen.”

Scientific names for organisms are the formally accepted names given by scientists so scientists all around the world understand quickly which organism is being spoken of. Scientific names of taxonomic groups are treated as Latin regardless of their derivation. They are usually Roman Latin or Greek Latin. For the most part plants are given the Greek origin. (Refer to pages 1 and 2 of the Glossary for a further in depth interpretation and the explanation for this.)

Scientific names have several components within a set order: Below I have used Coastal Wattle or Sally Wattle as an example. Note that not all the categories need to be filled.

  1. Kingdom Plantae
  2. Division Magnoliophyta
  3. Class Magnoliopsida
  4. Order Fabales
  5. Family Fabaceae
  6. Subfamily Mimosoideae
  7. Tribe N.A
  8. Genus Acacia
  9. Species longifolia
  10. Subspecies sophorea (Often shortened to subsp.)
  11. The authority or individual(s) responsible for the name.

Kingdom: Add ae to the end Plantae

Division: add ophyta to the end. Magnoliophyta

Class: add opsida to the end. Magnoliopsida

Clade: Generally Eudicots

Clade: lower level Generally Rosids

Order: add ales to the end of the genus name. Fabales

Family: add aceae to the end of the genus name. Fabaceae

Subfamily: add oideaeto the end of the genus name. Caesalpinioideae

Tribe: add eae to the end of the genus name.

Genus: Upper case first letter. Acacia

Specie: All lower case letters. complanata

The genus, species and the subspecies or variety names are either written in italics or underlined.

The Principle of Priority: The scientific names published at the earliest date will always take precedence over names of the same rank published at a later date. The first validly published name of a species (or other taxon) becomes its accepted scientific name.

In order to have a definite starting point, botanists have decided that for Angiosperms the starting date shall be from the time of publication of Species Plantarum, published in 1753 by Karl Linnaeus.

The International Code of Botanical Nomenclature lists exceptions and additions to this rule. This code is to maintain uniformity for botanists all over the world using the same system of names. There is disagreement over some plant groupings and today we have several proposed classification systems. Some of these systems have 20 or more principal groups of plants. Complicating matters further, the major classification groups for botany and zoology are different with names often overlapping at a family, genus and specific epithet level.

The Biocode is a movement to adopt only one classification system, for all types of living things. To avoid confusion, most literature usually refers only to family names and the genus and species of individual plants.

Common Plant Families

Botanists have adopted the Type Method to stabilize the determining characteristics of a species:

* The author of a species must designate a certain specimen as the Type Specimen of that species. 

* The Type Specimen is not necessarily the most representative of the group, it merely best shows the element on which the name for the group was originally based. 

* The Type Specimen fixes the strict concept of that species and the application of its name. 

* The Type Specimen is carefully preserved in a herbarium only accessible to research scientists. 

* To allow for damage or destruction of the Type Specimen, the system of Isotype, Lectotype and Neotype was devised for designating acceptable substitutes.

Holotype (Type Specimen): The original specimen designated by the author. “Types” are the most valuable of all specimens.

Universities and museums are very proud of the number of Type Specimens they have in their herbarium.

Isotype: Any specimen, other than the Holotype, that duplicates the Holotype. The isotype must come from the same collection, with the same locality, date, and number as the Holotype.

Lectotype: A specimen selected by a competent person from the original material studied by the author.

Neotype: A specimen selected to serve as a substitute for the Holotype when all material on which the name was based is missing.

Gymnosperms form “naked seeds”, not enclosed in fruit.

* Division Cycadophyta: Only about 100 species of cycads are alive today. They are found in the tropics and subtropics – Macrazamia cairnsiana.

* Division Ginkgophyta: The only living example is Ginkgo biloba. Ginkgo biloba has stood the rigors of Dinosaurs and the rise of the Qinghai Tibetan Plateau over the past 180 million years. The branching pattern of the veins are unique but were common amongst other primitive plants of its era.

* Division Gnetophyta: An odd group of cone-bearing plants with the xylem containing a vascular system more like Angiosperms than Gymnosperms. The three genera consist of around 70 living species today with none extending to Australia.

* Division Coniferophyta: Conifers are woody plants with needle or scale-like leaves that form cones. They include Callitris, Podocarpus and Prumnopitys.

Angiosperms from “enclosed seeds” in a fruit. Fruits are divided further into seeds, achenes, nuts, legumes, samaras, pomme, drubes, berries, lodicules etc. See Glossary page 18.

Division Anthophyta: The flowering plants. There are almost 320,000 species of angiosperms, making them the dominate Division within the plant hierarchy today.

In evolutionary terms Angiosperms are showing certain general trends.

* Many flower parts to fewer flower parts

* Parts separate to parts being fused

* Kinds of parts 4 to being less than 4

* Superior ovaries to inferior ovaries

* Actinomorphic to zygomorphic

There are two Classes of Angiosperms, based on their number of cotyledons (seed leaves).

Monocotyledoneae (the Monocots): all members of the group have one cotyledon or seed leaf.

  • About 100,000 species.
  • Fewer than 10mm of the species are woody.
  • Most are grasses followed by reeds and lilies with orchids then palms.

Seed Structure

Seedlings

Dicotyledoneae (the Dicots): all members of the group have two cotyledons or 2 seed leaves.

  • Around 210,000 species.
  • About 50mm of the species are woody.
  • A very diverse group.

Monocots and Dicots are the two most important groups of plants on the planet.
Plants are sometimes grouped using the common names below. While these are not taxonomy correct groups, understanding their use is helpful in describing the plants characteristics.

* Perennial plants continue to grow and flower for more than two years, and many live for decades or centuries. Most perennials die back to the ground in the winter, then sprout from their underground growth in the spring.

Tree – Dicotyledon Woody plants with one main stem. Grevillea robusta.

Shrub – Dicotyledon Woody plants with several stems growing from near the ground. Banksia spinulosa subsp. collina

Herb – Dicotyledon Herbaceous, soft, non-woody, flowering plants with broad leaves. Telopia speciousus

Grass & Reeds – Monocotyledon plants – Herbaceous flowering plants with narrow leaves and jointed stems. Juncus usitatus

Orchidacea – Monocotyledon plants with specialised flowers. Dendrobium teretifolium

ClimbersDicotyledon Plants with a trailing or twinning habit. Cissus antarctica

Succulent – Dicotyledon Plants with thick, fleshy tissues in the leaves & or stems for storing water. Sesuvium portulacastrum

Herbaceous plantsDicotyledon with green, non woody stems. Coleus torrenticola

Biennial plants – Dicotyledon live for two growing seasons. The first season they grow the herbaceous parts while the second season concentrates on the reproductive parts. Two growing seasons may occur over two years or as short as one year. Actinotus helianthi

AnnualsDicotyledon  live for one growing season. They will shoot, grow, flower, produce seeds, and die in the one growing season. Xerochrysum bracteatum

Remember:

1. The meaning of plant taxonomy is the grouping of plants based on their presumed relationships to each other. That is their common characteristics.
 
2. Species plantarum is the main work of Karl Linnaeus and is the starting point for modern Angiosperm botanical nomenclature
 
3. A plant Family name adds the Genus then the specific or epithet name to the end. 
 
4. Most literature refers only to the genus name, the specific epithet & the authority or person/s responsible for the name.

5. The Family Pinaceae has needle or scale type leaves. 
 
6. The International Code of Botanical Nomenclature sets the strict guidelines of the species and the application of the name applied.
 
7. Gynosperms form their seeds naked in woody cones where as Angiosperms form their seeds enclosed in fruit. 
 
8. All members of the Class Dicotyledoneae have two seedling leaves. 
 
9. Grasses and reeds are monocotyledon and have a single seedling leaf, flowering plants with narrow leaves and jointed stems. 
 
10. Annual plants complete their life cycle over one growing seasons, Biannual plants complete their life cycle over two growing seasons and perennial plants complete their life cycle over three growing seasons. 
 
11. Nomenclature is the application of names to plants. 
 
12. Scientific names of taxonomic groups are treated as Latin, regardless of their original derivation and are Latinized. 
 
13. The author of the scientific name is the individual responsible for the name. 
 
14. The Biocode is a movement that wants to adopt only one classification system for all living things.
 
15. “Pliny the Elder” tried to record “Everything known about the world. 
 
16. Theophrastus is known as the Father of Botany and began classifying plants 2500 years ago.
 
17. In a scientific name, the Genus and specific epithet names are   either italicized or underlined
 
18. Monocots have leaves that are usually parallel veined.

19. Holotype -Type Specimen is the original specimen designated by the author. “Types” are the most valuable of all specimens.

20. An isotype must conform to the Halotype in that it comes from the same collection, with the same locality, data, and number as the Holotype. 

21. Lectotype is a specimen selected by a competent person from the original material studied by the author.

22. Neotype is a specimen selected to serve as a substitute for the Holotype when all material on which the name was based is missing.

Further Comments from Members:

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