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Plant taxonomic keys - Botany

The document discusses the significance of botany, the study of plants, highlighting its role in ecosystem sustainability and human survival. It describes taxonomic keys and their types, particularly dichotomous keys, and outlines the steps involved in constructing a taxonomic key to identify plant species based on morphological characteristics. Emphasizing the expertise required for taxonomic work, it culminates in a call for collaboration among taxonomists and institutions to enhance the field's contribution to science.

Science◦
PLANT TAXONOMIC KEYS Dr. Joby Paul Research and Post Graduate Department of Botany St. Thomas' College [Autonomous], Thrissur, Kerala
Why Botany ? Botany is the scienceand artof studying plants, that carry out photosynthesis. Botany includes a wide range of scientific sub disciplines t h a t s t u d y t h e structure, growth, reproduction, metabolism, development, diseases, ecology and evolution of plants. The study of plants is important because they are a fundamental part of life on Earth, generating food, oxygen, fuel, medicine and fibers that allow other life forms to exist. Through photosynthesis they absorb carbon dioxide, a waste product generated by most animals and a greenhouse gas that contributes to global warming.
The ancient Greeks were among the first to write about plants in a scientific way. Aristotle believed plants ranked between animals and inanimate objects. Aristotle’s pupil Theophrastus wrote two books about plants that still were in use in the 15th century. The Swedish physician-turned-botanist Carl Linnéis considered the father of the systematic nomenclature, which he invented in the 18th century and still is used to give scientific names to all species, plant and otherwise.
The Identity crisis ?
Two contrasting phases We are now in a phase of critical evaluation of methodology, choice of data, assumptions, etc. because we are in the middle of two contrasting phases: ►Development in Molecular phylogeny by advance technology. ►High estimates of Biodiversity, Number of unidentified and misidentified species.
Are we equipped to face this challenge ? All we need Plant specimen Dissection microscope Flora Dedication
Differentiate these flowers A B C D E Flower Red ------------ A Flower Blue ----------- B Flower Yellow -------- C Flower Pink ----------- D Flower Cyan ---------- E
A B C D Flowers Red ------------ A and D [Group 1] Flowers Blue ----------- B and C [Group 2] Petals 5 ------------------A Petals 8 ------------------D Petals 5 ------------------B Petals 8 ------------------C
A B C D Petals 5 ------------------A and B [Group 1] Petals 8 ------------------C and D [Group 2] Flowers Red ------------ A Flowers Blue ----------- B Flowers Blue ----------- C Flowers Red ------------ D
A B C D Leaves opposite ------------------------------------ A and C [Group 1] Leaves alternate ------------------------------------ B and D [Group 2] Flowers Red, Petals 5 ------------------------------A Flowers Blue, Petals 8 -----------------------------C Flowers Blue, Petals 5 -----------------------------B Flowers Red, Petals 5 ------------------------------D
What is a Taxonomic Key ? A key is a device, which when properly constructed and used, enables a user to identify an organism. Keys are devices consisting of a series of contrasting or contradictory statements or propositions requiring the identifier to make comparisons and decisions based on statements in the key as related to the material to be identified. The key consists of a series of choices, based on observed features of the plant specimen. It provides a choice between two contradictory statements resulting in the acceptance of one and the rejection of the other. A single pair of contradictory statements is called a couplet and each statement of a couplet is termed a lead. By making the correct choice at each level of the key, one can eventually arrive at the name of the unknown plant.
Types of Taxonomic Keys Dichotomous Keys: Keys in which the choices allow only two (mutually exclusive) alternative couplets are known as dichotomous keys. In constructing a key, contrasting characters are chosen that divide the full set of possible species into smaller and smaller groups i.e. the statements typically begin with broad characteristics and become narrower as more choices are required. Dichotomous comes from the Greek root dich meaning “two” and temnein meaning “to cut“. Each time a choice is made, a number of species are eliminated from consideration and the range of possible species to which the unknown specimen may belong is narrowed. Eventually, after sufficient choices have been made, their range reduces to a single species and the identity of the unknown plant is revealed.
Types of Dichotomous Keys Indented Keys (also called yoked): Indents the choices (leads) of the couplet an equal distance from the left margin. The two choices of the couplet are usually labelled 1 and 1′or 1a and 1b. It is not necessary that the choices are numbered, but it helps. The user goes to the next indented couplet following the lead that was selected.
Bracketed Keys: Provides both choices side-by-side. The choices of the couplet must be numbered (or lettered). It is very helpful if the previous couplet is given. This key has exactly the same choices as the first example. The choices are separated, but it is easy to see the relationships. While this key might be more difficult to construct, it gives more information to the user.
Poly Clave Keys: Another type of key, which is relatively a new alternative to dichotomous keys and becoming increasingly popular, especially because of the ease of computerizing them, is termed multiple access or poly clave or synoptic key. The advantage of these keys is that they allow the user to enter the key at any point. This key is based on the identification of organisms by a process of elimination. In a written poly clave key there is a series of characters and character states. Each state is followed by a number or code for the species that possess that feature. The user needs to select any character and then copy down the list of species that possess the feature. Then the user has to select another character and eliminate any species that is not common to both lists. This process has to be continued until the specimen is identified.
Websites: • http://www.discoverlife.org/mp/20q?guide=Trees • http://eekwi.org/veg/treekey/ • http://webikey.agron.iastate.edu/SelectCategories.aspx • https://gobotany.newenglandwild.org/full/ • http://delta-intkey.com/angio/ • https://plants.usda.gov/java/ • https://www.wildflower.org/plants/ Apps: Leafsnap Tree ID Virginia Tech Tree ID The tree app PlantSnapp
Realtime time Taxonomic Key construction Step 1 Collect leaves of FIVE neighbourhood plants
Step 2 Write the morphological data in the following data sheet Data sheet [Taxon card] for leaf morphology [Fill the data for each species] Character Hibiscus Chromolaena Ixora Mango Ficus Simple / Compound Simple Simple Simple Simple Simple Phyllotaxy Alternate Opposite Opposite Alternate Alternate Petolate Petiolate Petiolate Petiolate Petiolate Petiolate Lamina Shape Ovate Elliptic Elliptic Lanceolate Cordate Lamina colour Light green Light green Dark green Light green Dark green
Leaf base Rounded Acute Rounded Cuneate Cordate Leaf apex Acute Acuminate Acute Acuminate Acuminate Leaf margin Serrate Serrate Entire Undulate Undulate Upper surface Hairy / glabrous Glabrous Pubescent Glabrous Glabrous Glabrous Lower surface Hairy / glabrous Glabrous Glabrous Glabrous Glabrous Glabrous
Step 3 Compare the species for similarities as follows. [Highlight with colour or underline with color for similar characters] Character Hibiscus Chromolaena Ixora Mango Ficus Simple / Compound Simple Simple Simple Simple Simple Phyllotaxy Alternate Opposite Opposite Alternate Alternate Petolate Petiolate Petiolate Petiolate Petiolate Petiolate Lamina Shape Ovate Elliptic Elliptic Lanceolate Cordate Lamina colour Light green Light green Dark green Light green Dark green
Leaf base Rounded Acute Rounded Cuneate Cordate Leaf apex Acute Acuminate Acute Acuminate Acuminate Leaf margin Serrate Serrate Entire Undulate Undulate Upper surface Hairy / glabrous Glabrous Pubescent Glabrous Glabrous Glabrous Lower surface Hairy / glabrous Glabrous Glabrous Glabrous Glabrous Glabrous
Step 4 Write down Taxonomic key [First, group in to two sets based on the similarities of characters in the data table, then divide each group in to further until all individual species are separated] 1 a. Leaves alternate ---------------------------------[Hibiscus, Mango and Ficus] 2a 1 b. Leaves opposite ---------------------------------[Chromolaena and Ixora] 4a 2 a. Leaf apex acuminate --------------------------- [Mango and Ficus] 3a 2 b. Leaf apex not acuminate ----------------------[Hibiscus] 3 a. Lamina lanceolate ------------------------------ [Mango] 3 b. Lamina cordate ----------------------------------[Ficus] 4 a. Leaf margin serrate -----------------------------[Chromolaena] 4 b. Leaf margin entire ------------------------------[Ixora]
Step 5 Include additional contrasting characters [if available], to finalize the Taxonomic key. 1 a. Leaves alternate ---------------------------------[Hibiscus, Mango and Ficus] 2a 1 b. Leaves opposite ---------------------------------[Chromolaena and Ixora] 4a 2 a. Leaf apex acuminate --------------------------- [Mango and Ficus] 3a 2 b. Leaf apex not acuminate ----------------------[Hibiscus] 3 a. Lamina lanceolate ------------------------------ [Mango] 3 b. Lamina cordate ----------------------------------[Ficus] 4 a. Leaf margin serrate, apex acuminate ------ [Chromolaena] 4 b. Leaf margin entire, apex acute -------------- [Ixora]
Work at home
Basic requisites for a good taxonomist Knowledge of classics Knowledge of Latin Ability to describe neatly and clearly (Language skill) Good illustrations Good photographs Common sense
What we need is NETWORK WITH EXPERTS AND INSTITUTIONS DO THINGS USEFUL TO A LARGE NUMBER OF PEOPLE AND NEEDED BY THE COUNTRY: MONOGRAPHS AND REVISIONS BETTER BE A FIRST RATE CLASSICAL TAXONOMIST YOUR INTEGRITY, COMMITTMENT AND COMPETANCE ARE THE KEY TO THE USEFULNESS AND LONGEVITY OF YOUR CONTRIBUTION TO SCIENCE
Taxonomy is the Servant and Queen of Biology Provides basic information regarding identification, close relatives etc of plant species that are in need It is a synthetic discipline constructing a system of classification based on analysis of all type of evidences from the entire life cycle of organisms
Plant taxonomic keys - Botany