The laboratory component of General Botany provides you the opportunity to view interrelationships between and among structures, to handle live or preserved material, to become familiar with the many terms we use throughout the course, and to learn how to use a microscope properly. Each of you will have your own microscope every week, no exceptions. This laboratory is fundamental, yet integral to your understanding of General Botany. The images in your manual are intended to serve as a guide while you view permanent or prepared slides. These must be viewed by each of you independently. At no time will questions be answered re where is a particular structure, etc. unless the slide is on the stage of your microscope and in focus. The content of the laboratory is rich, as is the terminology. You must come to lab prepared. You must come to lab knowing what the various terms you are about to deal with mean. There is no such thing as finishing early that simply isn't possible. In some laboratory exercises you will be asked to identify structures of an organism. For example, Examine slide 9 labeled Rhizopus sporangia w.m. and identify the mitosporangia, mitospores, columella, mitosporangiophore, and zygotes. In all likelihood you will only be able to see mitosporangia, mitospores, columella, and mitosporangiophores. If zygotes are absent in your slide you note that the population of hyphae you are examining are only reproducing asexually. These questions are written in this manner to further fortify your understanding of the organisms in question and not to trick you. Thinking about what you are viewing is not an option but a necessity! The phylogeny we have adopted in this course is a composite. No single phylogeny best reflects our collective understanding of all the organisms included in this course so we have created one that reflects modern thought and is based on both morphological and molecular data.
General Botany Laboratory Manual
By Jerry G. Chmielewski David KrayeskyAuthorHouse
Copyright © 2013 Jerry G. Chmielewski & David Krayesky
All right reserved.ISBN: 978-1-4772-9653-0Chapter One
Classification
We have historically classified objects because it adds order to our lives by facilitating access to these objects, by providing an understanding of them, or by allowing for the easy dissemination of information about them. Basic classification schemes we use today can be found on your hard drive, in the hardware store, the library, a lumberyard, auto wreckers, or your closet. Check out your wardrobe, socks in this drawer, underwear in another, and T-shirts in yet another. One of the major differences between the ways in which you or a respective business may classify their objects is that there is no right or wrong way to construct the groupings – whatever works best for you or the business is deemed acceptable.
Unfortunately the same does not hold true for the biologist. Faced with the daunting task of grouping and naming the world's nearly 2 million species, and in fact the real number may be 14-30 million species, the biologist must adhere to strict naming rules as defined by one of the following: International Code of Nomenclature for algae, fungi, and plants (ICN which replaced the International Code of Botanical Nomenclature – ICBN in July of 2011), the International Code of Nomenclature for Cultivated Plants (ICNCP); the International Code of Zoological Nomenclature (ICZN); International Code of Nomenclature of Bacteria (ICNB); International Committee on Taxonomy of Viruses (ICTV); and the International Code of Phyto socio logical Nomenclature (ICPN). The work must also be peer reviewed and published in a source acceptable to the scientific community before the newly created group has the potential for having scientific merit. Encompassed within these millions of organisms is a phenomenal amount of intra-group and inter-group variation.
Taxonomy (from the Greek taxis for arrangement and nomia for method) is that part of the biological sciences that deals with the identification, naming, and arrangement of organisms in a classification scheme. Written taxonomic history can be traced to Theophrastus of Eresos, the intellectual grandfather of modern botany who classified plants as herbs, shrubs, or trees as early as 300 BC. One of the defining periods in taxonomic history occurred during the 18th century and is specifically associated with the work of Carl von Linne (1707-1778), a Swedish botanist known more commonly as, Carolus Linnaeus (Latin was the language of choice among European scientists so writings and oftentimes names were Latinized) who championed the system of biological nomenclature in common use today. In truth, the binomial system of classification was first proposed by Gaspard (Casper) Bauhin (1560-1624).
Prior to Linnaeus' time there were no commonly accepted standards for naming. As such, organisms tended to have long, cumbersome, descriptive names. For example, botanists referred to the common wild briar rose as Rosa sylvestris alba cum rubore, folio glabro which from Latin roughly translates to pinkish white woodland rose with hairless leaves. The Linnaean system of classification brought order to a chaotic science and is founded on the use of binomial nomenclature wherein each of the basic units of classification is given two names (thus a binomial), a genus name and a species name, with the concurrent requirement that these form a pair and are stated together.
Linnaeus referred to the binomial as the nomen trivial (trivial name). Today, the binomial, or more specifically, the Latin binomial, constitutes what is referred to as the scientific or specific name. For example, Quercus alba is the white oak. Note that the scientific name is italicized and that the first part of the binomial, the genus name is capitalized, whereas the second part, referred to as the specific epithet or species is not capitalized. The genus name is a noun and singular and the species name is usually an adjective but may be a noun. Both are Latinized.
The Linnaean system of classification is viewed as being hierarchical in that each organism is placed within the lowest most group, the species, and closely related species occur in a larger group, the genus (plural genera). Related genera are grouped into a family, families into an order, orders into a class, classes into a phylum (formerly division in the botanical literature), and phyla (plural of phylum) into a Kingdom. Groups of all sizes, from species to Kingdom, are called taxa (singular taxon). The taxonomist is given the latitude to define groups how they choose and in doing so no set number of diagnostic characteristics, no special types of characters, and no special number of characters are involved in the designation of any group of organisms at a particular rank.
All classification schemes have a morphological bias out of necessity. It is possible that during the course of formulating groups that morphological, physiological, ecological, molecular, or chromosome data was used, though when it comes time to actually identify a specimen in hand in the laboratory or field only morphological data is readily available. Further, typically only those characteristics that can be identified with the naked eye or with the use of a hand lens are appropriate for inclusion in the character suite used to define the species. For this reason all classification schemes exhibit a morphological bias.
Although biologists have historically chosen to incorporate aspects of sexual reproductive biology in their definition of the species concept it is prudent not to do so because the strong majority of described species DO NOT undergo sexual reproduction. The best workable definition across all species boundaries, bacterial, viral, fungal, algal, plant, or animal is:
"a species is the smallest identifiable group of organisms that share more characteristics in common with each other than they do with any other group of organisms".
ALTERNATE LEAF ARRANGEMENT
ANDROECIUM
ANTHER SAC
CALYX
COMPOUND LEAF
COROLLA
DECUSSATE LEAF ARRANGEMENT
DICOT
DIOECIOUS
FERTILE SERIES
FILAMENT
FLORAL SERIES
GENUS
GYNOECIUM
INFLORESCENCE
LATIN BINOMIAL
LEAF BLADE
MONOCOT
MONOECIOUS
OPPOSITE LEAF ARRANGEMENT
OVARY
OVULES
PALMATE VENATION
PARALLEL VENATION
PEDICEL
PEDUNCLE
PERIANTH
PETAL
PETIOLE
PISTIL
RETICULATE VENATION
SEPAL
SIMPLE LEAF
SPECIES
SPECIFIC EPITHET
STAMEN
STERILE SERIES
STIGMA
STYLE
TEPAL
WHORLED LEAF ARRANGEMENT
Label the sepals, petals, stamens, filaments, anther sacs, pistil, stigma, style, ovary, and ovules. What type of placentation does this flower have? Is this flower actinomorphic or zygomorphic? Is this flower primitive or advanced? What about the following?
Taxonomy, What's in a Name?
Taxonomy, a term coined by the Swiss botanist Candolle (1813), initially referred to the endeavor of plant classification, that is, the use of morphological characters to order organisms into groups based on their similarities and differences. Today, taxonomy is a more generally used term applied to the act of classifying any group of organisms. Once organisms are placed into a group, that is classified, a taxonomist must apply a unique name to that group following a strict set of globally accepted rules. The naming of groupings of like organisms and the rules that govern the assignment of names is called nomenclature.
"It has been already suggested, and forcibly enough, that plant taxonomy was not invented in any school, or by any philosopher; that it is everywhere as old as language; that no plant name is the name of an individual plant, but is always the name of some group of individuals, and that all grouping is classifying." Edward Lee Greene in Landmarks of Botanical History (1909), page 106.
Insofar as Candolle may be credited with coining the term taxonomy, the beginnings of taxonomy must realistically predate recorded history. Further, it could be argued that taxonomy is the world's oldest profession as the earliest of men must have been practical taxonomists out of necessity. As a gatherer society our early ancestors had to be able to communicate with each other regarding the difference between edible and inedible plant matter. Similarly they would have needed to learn about and communicate the difference between for example poisonous and non-poisonous snakes, or the differences among edible, poisonous, and hallucinogenic mushrooms. Clearly their survival was dependent upon their ability to distinguish between or among groups of organisms and concurrently effectively communicate these differences among their social group. Those who failed to learn this distinction in all likelihood also failed to become our ancestors.
Today taxonomy may be subdivided into three branches, alpha or descriptive taxonomy, beta or systemizing taxonomy, and gamma or evolutionary taxonomy. Alpha taxonomy is the level of taxonomy that is concerned with the characterization and naming of species. Many would argue that for all intents and purposes alpha taxonomy is for the most part a piece of the past, though if we consider that only 2 million of the possible 14-30 million species on Earth have been named the potential is staggering. Beta taxonomy is that level of taxonomy concerned with the arrangement of species into a natural system of higher and lower taxa. Relationships between and among species are worked out more carefully and emphasis is placed on sound classification. In truth, Beta taxonomy involves a re-evaluation of the efforts of the alpha taxonomist and entails much of the taxonomy being done today. Gamma taxonomy, also known as evolutionary taxonomy is the level of taxonomy dealing with various biological aspects of taxa including intra-specific studies, speciation, and evolutionary rates and trends and like Beta taxonomy entails much of the taxonomy being done today.
The layperson may argue that the binomial system of nomenclature championed by Linnaeus is too difficult to comprehend because of its Latin roots and as such would prefer to use a system that employs common names instead. Several reasons can be given as to why this approach is impractical: 1. common names are not universal and can have different meanings in different languages; 2. most of the world's organisms do not have common names; 3. many unrelated organisms have been given the same common name; 4. because no rules were established historically for the assignment of common names they have been applied indiscriminately to genera and species; and 5. a single species may be known by more than one common name in the same or different localities.
Although identification may be deemed to be a basic activity it is the primary objective of taxonomy and involves both classification and nomenclature. In its simplest form identification is the determination of similarities and differences between or among objects – they are the same or they are different. The four traditional methods employed to identify unknown specimens include expert identification, recognition, comparison, and the use of keys or similar devices.
Using an expert to identify an unknown specimen would be ideal for many reasons, but realistically, one is typically not on hand for consultation, nor generally concerned with the queries of a layperson. Recognition as a means of identification presupposes past experience and a knowledge base that a neophyte to the world of identification simply would not have. The likelihood of success using the comparison method is very much dependent upon the suitability of the materials used for comparative purposes. Realistically these materials commonly do not extend beyond local field guides or picture books of the more common species and as such are limited in their usefulness. Thus, for the fledgling naturalist the most readily available, reliable, and useable method of specimen identification is through the use of taxonomic keys or similar devices. In the most traditional sense taxonomic keys consist of successive pairs of contrasting statements relating to morphological features of the organism(s) under consideration and culminate in identification. The usage of contrasting pairs of statements, or couplets, in the identification of organisms dates back to Jean de Lamarck in 1778 and has since then been the dominant format employed.
Although the aforementioned key is dichotomous in design and that which is most commonly available and utilized, provision does exist for the possibility of multiple equal statements to be incorporated within a key. Rarely though is the latter implemented. Using a key can be likened to traveling a roadway from point A to B while following directions. Whenever you get to an exit or an intersection you need to make the correct choice to ultimately arrive at the destination you seek. Unlike roadways in which many different routes may be selected to arrive at a certain destination, only a single pathway through a dichotomous key will get you to a specific end point.
Dichotomous keys may be either indented or bracketed. Botanists typically use the indented type whereas zoologists prefer the bracketed type.
Indented Key
1. Fruit a pome; ovary inferior 2
2. Petals absent 3
3. Sepals usually 4; involucre absent Plant 1
3. Sepals usually 5; involucre present Plant 2
2. Petals present Plant 3
1. Fruit a hesperidium; ovary superior 4
4. Flowers regular; spurs 5 Plant 4
4. Flowers irregular; spur 1 Plant 5
To use the indented key read both statements with the lowest number (1) and select that which is most correct. Assuming you have chosen the first of these read both options numbered 2. Assuming the first of these is most correct read both options numbered 3. Select the most appropriate of these and you have identified the specimen to genus.
Bracketed Key
1. Fruit a pome; ovary inferior 2
1. Fruit a hesperidium; ovary superior 4
2. Petals absent 3
2. Petals present Plant 3
3. Sepals usually 4; involucre absent Plant 1
3. Sepals usually 5; involucre present Plant 2
4. Flowers regular; spurs 5 Plant 4
4. Flowers irregular; spur 1 Plant 5
To use the bracketed key read both statements with the lowest number (1) and select that which is most correct. Assuming you have chosen the first of these next go to the statements numbered 2 – read both options. Assuming the first of these is most correct go to the statements numbered 3 and read both options. Select the most appropriate of these and you have identified the specimen to genus.
One of the primary drawbacks in the use of dichotomous keys by the non-professional rests in the typically technical terminology incorporated within the couplets. As you read through either the indented or bracketed key you should have noticed that several technical terms are included. For example, do you know what is meant by achene, follicle, spur, petal, sepal, involucre or flowers being regular versus not? Not knowing the terminology specific to the type of organism you are trying to identify is the major drawback to the use of dichotomous keys. Phytography is that part of taxonomy which deals with the description of plant parts. Although its intent is to portray accuracy and completeness of description in the fewest number of words possible it is a point of frustration for the neophyte user. This limitation can however be easily remedied through the use of less technical, though equally accurate descriptive terminology. In reality, the trend in newer keys is to use terminology directed toward usage by the non-professional as opposed to the professional biologist. The second primary restriction of dichotomous keys is that by their very structure a single point of entry is mandated. That is, the user must begin at the first couplet in the key and sequentially progress through subsequent couplets until the respective specimen is identified. Whether intended or not, the single point of entry implies a hierarchy in the characters used to distinguish among specimens. Greater latitude in this regard is however provided through polyclonal, or synoptical, keys. These multi-entry, or any-order, keys have historically used cards stacked in any arrangement, one on top of the other, with holes or edges punched such that cards with the desired taxa to be retained are eliminated until the card with the desired taxa listed on it is the only card remaining. Today though, the personal computer offers the possibility for automated identification using multi-entry keys as well as key construction per se. Further, the personal computer also permits microcomputer-assisted telephone identification of plants and a new mobile app can be used to identify plants by leaf shape. How far we have come since the days of Linnaeus.
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Excerpted from General Botany Laboratory Manualby Jerry G. Chmielewski David Krayesky Copyright © 2013 by Jerry G. Chmielewski & David Krayesky. Excerpted by permission of AuthorHouse. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
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