PH-BPS 112L Plant Nomenclature and Taxonomy Exercise PDF

De La Salle Medical and Health Sciences Institute PH-BPS 112L (Pharmaceutical Botany with Taxonomy) Dr. Mariano Que College of Pharmacy Plant Nomenclature and Taxonomy PLANT NOMENCLATURE AND TAXONOMY De La Salle Medical and Health Sciences Institute PH-B...

De La Salle Medical and Health Sciences Institute PH-BPS 112L (Pharmaceutical Botany with Taxonomy) Dr. Mariano Que College of Pharmacy Plant Nomenclature and Taxonomy PLANT NOMENCLATURE AND TAXONOMY De La Salle Medical and Health Sciences Institute PH-BPS 112L (Pharmaceutical Botany with Taxonomy) Dr. Mariano Que College of Pharmacy Identification and Taxonomic Keys EXERCISE NO. 9 Identification and Taxonomic Keys OBJECTIVES At the end of the exercise, the student should be able to: Construct a key to some plant specimens; and Identify a plant sample using a taxonomic key THEORY The process of learning the names of plants can be done in various ways. The easiest and probably the most used method is to ask someone who already knows. In this way, the knowledge of another individual is utilized. The second most used method of learning plant names is to compare an unknown second plant with a photograph or picture of a similar plant in a book. The third way is to identify the plant by yourself. To have the skill to identify an unknown plant oneself is a most valuable asset and a valuable part of the study of systematics. Identification of unknown specimens is usually made by using a key. A key is a device where successive choices between contrasting statements are followed until the correct name is found by the process of elimination. Keys play an integral part in Flora, allowing for the proper identification of families, species and infraspecific taxa. Keys are usually dichotomous, which means a choice is provided between two contradictory statements resulting in the acceptance of one and the rejection of the other. The use of a dichotomous key is like following directions given by a friend to a distant destination. As one travels down a road or a highway, decisions are made at road junctions as to which way to turn. If the roads are properly marked and if the directions are followed carefully, the destination can be reached. The same is true with following the paired choices of a dichotomous key. The most common and simplest type of key is the dichotomous bracketed key. It consists of pairs of contrasting characters or couplets, each statement of which is a lead. Both the leads are numbered and begin with the same word as much as possible. At the end of each line, there is a number of a name referring to a couplet. A sample key to the five genera of the family of Ranunculaceae is given below: (1) Fruit of a group of achenes, unspurred flowers …………………….. (2) (1) Fruit of a group of follicles, spurred flowers …………………….. (4) (2) Petals absent …………………….. (3) (2) Petals present …………………….. Ranunculus (3) Sepals usually 4, involucre absent …………………….. Clematis (3) Sepals usually 5, involucre present …………………….. Anemone (4) Spurs 5, flowers regular …………………….. Aquitegia (4) Spurs 1, flowers irregular …………………….. Delphinium In a numbered key (just like the example above) each couplet has its two leads immediately adjacent, one below the other under the same number on the left-hand side of the De La Salle Medical and Health Sciences Institute PH-BPS 112L (Pharmaceutical Botany with Taxonomy) Dr. Mariano Que College of Pharmacy Identification and Taxonomic Keys page. The first couplet to be read stands at the top of the key under the number 1 on the left-hand side of the page. Thus, in the example the first pair of contrasting statement refer to fruits. Opposite the leads in the right-hand side of the page, you will note there are other numbers =, namely 2 and 4. These are reference numbers to further down the key. In a numbered key, it is by means of such numbers that the user is directed to the next appropriate couplet to consult until the identification of the specimen is made. A key should employ easily seen characters. They should also be ones that are likely to be reliable and constant. The contrasting characters in each lead of a couplet must really contrast and the contrast must be stated clearly and precisely in the key. It is preferred if several different contrasting characters are used in each couplet. If this is done, they not only reinforce one another and thus increase the certainty of correctly determining the species but they can be chosen to represent various life stages of the plant. For this reason, vegetative characters are best used if suitable ones exist. If not, both the flowering and fruiting characters should be used in the same couplet. There are some limitations, though, to using keys in identification. These limitations should be avoided when making one. If a key you are using appears not to work, there may be some deficiency in the key. Even if the contrasting characters are real ones, they may be so poorly chosen and indistinct as to be of little use in discriminating between the plants concerned. Sometimes good characters are not useful if these are not expressed well. For example, “leaves large” and “leaves small” is a useless heading in a key because the user would not know what “large” and “small” mean. A key may also fail to work if the specimen you are trying to name is a hybrid or an intermediate in its characters between two of the species that are separated in the key. Below are some short-cut reminders about making and using identification keys: 1. The key is dichotomous (i.e., forking). They always come in pairs. 2. The first word of each lead of the couplet should be identical. 3. The two parts of the couplet should be made up of contradictory statements so that one part will apply and the other will not 4. No character of the plant should be used alone in the key without using its contrasting alternative condition in the other half of the couplet 5. Avoid the use of overlapping ranges or vague generalities in the couples; for example: 4 to 8 mm in length versus 6 to 10 mm in length or small versus large. 6. Use readily observable features. Use more than one feature and not more than three. Avoid using geographical location as a sole separation character. 7. Couples of a key may be numbered or lettered or may use some combinations of lettering and numbering. MATERIALS Plant specimen used in herbarium Blade Dissecting microscope PROCEDURE 1. Construct a key of selected plant sample. De La Salle Medical and Health Sciences Institute PH-BPS 112L (Pharmaceutical Botany with Taxonomy) Dr. Mariano Que College of Pharmacy Identification and Taxonomic Keys a. List the characteristics of the chosen plant sample. b. Determine its characteristics that can separate it into other plants. c. Continue until the plant is separated into small groupings and specific characteristics differentiate one vegetable from the others. 2. Use the two keys below to identify the plant assigned to you. Before using the key, observe the taxonomic character of the species and record them. The characters of the species will help you determine the identity of the class, subclass, and family of the plant. Key to the Major Groups of Plants 1. Plants with seeds, ovules enclosed within the ovary………………………………… Angiosperms 2. Flowers mostly tetra to pentamerous, two cotyledons…………………….…. Dicotyledons 3. Both sepals and petals present 4. Petals are free; flowers with calyx and corolla………………...Polypetalae 4. Petals are fused; flowers with calyx and corolla……………. Gamopetelae 3. Either sepals or petals are present; rarely both absent…………. Monochlamydae 2. Flowers mostly trimerous, one cotyledon…………………………………. Monocotyledons 1. Plants with seeds, ovules exposed, i.e., not enclosed within the ovary……………. Gymnosperms Key to the Classes and Subclasses of Angiosperms (after Cronquist) A. Plants with net-veined leaves, flower parts in 4s or 5s …………… Magnoliopsida B. Flowers polypetalous with numerous stamens, pollen uniaperture …………… Magnoliidae BB. Plants different from above, pollen w/ more than one aperture …………… C C. Flowers reduced with insconspicuous perianth, often unisexual in catkins …………… Hamamelidae CC. Flowers not as above …………… D D. Flowers sympetalous, stamens fewer than petal lobes or alternating w/ petals …………… Asteridae DD. Flowers often apopetalous or if sympetalous, w/ more stamen than petal lobes …………… E E. Flowers usually polypetalous and w/ axile placentation …………… Rosidae EE. Flowers often sympetalous, and if w/ axile placentation, w/ many ovules per carpel …………… F De La Salle Medical and Health Sciences Institute PH-BPS 112L (Pharmaceutical Botany with Taxonomy) Dr. Mariano Que College of Pharmacy Identification and Taxonomic Keys F. Pollen trinucleate, plants usually herbaceous …………… Caryophyllidae FF. Pollen binucleate, plants often woody …………… Dilleniidae AA. Plants with parallel-veined leaves, flower parts in 3s …………… Class Liliopsida G. Flowers usually apocarpous, plants herbaceous often aquatic …………… Alismatidae GG. Flowers mostly syncarpous, plants terrestrial …………… H H. Flowers w/ well differentiated sepals and petals …………… Commelinidae HH. Petals and sepals similar or flowers reduced and clustered to form a spadix unsheathed with a spathe …………… I I. Flowers numerous, small, often aggregated into spathe and spadix, leaves typically broad …………… Arecidae II. Flowers not aggregated, leaves narrow …………… Liliidae Key to Some Common Families A. Disc absent; flowers mostly bisexual, actinomorphic (or slightly zygomorphic in some members of Malighiaceae) B. Carpels at maturity splitting into three nut-like parts, often winged; stamens often united below, some of them often staminoidal …………… Malpighiaceae B. Carpels at maturity not splitting apart as above C. Leaves three foliate or pinnately compound; sap sour; capsule or berry often elongate …………… Oxilidaceae C. Leaves simple D D. Petals without ligulate appendage; ovary five-loculate; normally all developed …………… Linaceae D. Petals with ligulate appendage on inner side; ovary three- to four-loculate but only one developed …………… Erythroxylaceae A. Disc present, annular or of separate glands B. Flowers usually bisexual; or if unisexual then dioecious or polygamous; petals present C. Flowers actinomorphic D. Often leaves gland-dotted, of aromatic or pungent odor when bruised; stamens free or rarely united at the base only E. Leaves mostly gland-dotted; ovary mostly four- to five-lobed …………… Rutaceae E. Rarely leaves gland-dotted F. Ovary mostly deeply two to five-lobed or carpels nearly De La Salle Medical and Health Sciences Institute PH-BPS 112L (Pharmaceutical Botany with Taxonomy) Dr. Mariano Que College of Pharmacy Identification and Taxonomic Keys free; stamens often with a scale at the base; ovule usually solitary in each locule; trees or shrubs often with a very bitter bark …………… Simaroubaceae D. Leaves not gland-dotted; stamens often completely connate into a tube with the anthers inside …………… Meliaceae C. Flowers zygomorphic, superficially papilionaceous, syncarpus with axile or apical placentation …………… Polygonaceae B. Flowers usually bisexual; or if unisexual then dioecious or polygamous; petals present …………… Euphorbiaceae