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AGSC 284 SPRING 2009 LABORATORY I OUTLINE Introduction Weed Classification Botanical Habitat Life Cycle Morphology Physiology Weed Identification Broad-Leaved Weeds Narrow-Leaved Weeds Weed Collection Pressing Plant Specimens Mounting Plant Specimens Specimen Observations Cd Demonstration AGSC 284 Laboratory IA WEED IDENTIFICATION AND COLLECTION Identification of the weed species is the first step in developing a successful weed control program. Weed species differ with respect to their life cycle, mode of reproduction, rate of growth, shape of the developing shoot and root systems, competitive ability, requirements for light, nutrients, and temperature, and their resistance to particular control measures. Taxonomic identification is the most accurate, but in the field, one does not often have time for comprehensive and accurate taxonomic verification. Classical taxonomists depend on flower parts as primary identification criteria. While weed scientists must identify weeds at much younger stages of growth, before the flowering parts appear. This is important in identification of grasses where differences in leaf blades, leaf sheath, ligule, auricles, collar are very helpful. Therefore, in order to make a prompt and correct identification you should master to visually distinguish weeds in all stages of growth. This can be obtained if you are acquainted with certain weed characteristics such as leaf shape, surface texture, venation, perennial reproductive structures, and distinctive odours. This fundamental knowledge is an essential prerequisite to competency in weed control. Knowledge of binomial nomenclature is essential for proper identification. All know that common names of weeds vary between countries, regions and even within the same region. Thus we have to adopt a binomial nomenclature system. This system is not designed to confuse you. It is a system, originally devised by the Swedish botanist Linnaeus, to bring order out of chaos. The lab Instructor will demonstrate the system for collecting and mounting herbarium specimens. You will be required to collect 25 weed specimens. This collection will be due on Monday, May 15, 2009 and will be returned on request. We will be available to assist in identification. The collection should include: 1. 2. 3. 4. A maximum of 10 weedy grasses. Representative from 7 plant families. Each specimen should be numbered. Each specimen must be accompanied by card label (or stamped; stamp is available in room 510) affixed in the lower right-hand corner with the appropriate information, in the form shown below. SCIENTIFIC NAME: COMMON NAME: FAMILY: LOCATION COLLECTED: DATE COLLECTED: COLLECTOR: 5. A one-page table of contents listing the 25 species in the order in which they appear in your collection The collection must be submitted as mounted specimens or with each dried and pressed plant placed in the fold of 1/2 sheet of newspaper (around 25 by 40 cm). Collections submitted in other ways or in larger size newspapers will be returned ungraded. The collection will be graded based on followings: Incorrect genus and species Incorrect species Incorrect family Missing specimen Incorrect spelling Poor specimen Missing table of contents -4 -2 -1 -4 -2 -2 -4 A List of 40 common broad-leaved weeds is attached and a set of images of the listed 40 broad-leaved weeds, list of 16 common narrow-leaved weeds and 4 parasitic weeds will be placed on the Moodle. Both lists do not include all of the important weeds. It includes many common weeds of Lebanon and Asia. You are required to be able to identify each of these weeds in any growth stage, by its scientific and family names. The weed identification quiz (April 6, 2009) will include any of the weeds/seeds on the attached lists. Most of the quiz specimens will be a combination of mounted herbarium specimens and fresh plants. AGSC 284 Common Broad-Leaved Weeds (40) Scientific Name Common Name English Amaranthus retroflexus Anagallis arvensis Anthemis hyalina Capsella bursa-pastoris Chenopodium album Chrysanthemum leucanthemum Cirsium libanoticum Convolvulus arvensis Datura stramonium Diplotaxis erucoides Erigeron linifolius Erodium romanum Euphorbia helioscopia Galium tricorne Fumaria spp. Heliotropium villosum Lactuca serriola Lamium amplexicaule Malva rotundifolia Medicago hispida Mercurialis annua Oxalis cernua Papaver spp Parietaria judaica Plantago major Portulaca olercea Polygonum aviculare Ranunculus arvensis Raphanus raphanistrum Ricinus communis Senecio vulgaris Sinapis arvensis Solanum nigrum Sonchus oleraceus Taraxacum officinale Tribulus terrestris Trifolium repens Urtica urens Veronica polita Xanthium stramarium Solanum nigrum Sonchus oleraceus Redroot pigweed Scarlet pimpernel May flower Shepherd's-purse Lambsquarters Oxeye daisy Lebanese plumed thistle Field bindweed Jimson-weed White rocket Hashish-ul-jabal Roman stroksbill Sun spurge Dibbaykah White fumitory Heliotrope Wild lettuce Henbit Khubbazi, Mallow Burclover Annual mercury Nodding wood sorrel Poppy Basal-leaved pellitory Broadleaf plantain Common purslane Prostrate knotweed Corn buttercup Wild radish Castorbean Commongroundsel Wild mustard Black nightshade Sow thistle Dandelion Puncturevine White clover Hurrayk, nettle Girey speedwell Cocklebur Black nightshade Sow thistle Family Life Cycle Amaranthaceae Primulaceae Asteraceae Brassicaceae Chenopodiaceae Asteraceae Asteraceae Convolvulaceae Solanaceae Brassicaceae Asteraceae Geraniaceae Euphorbiaceae Rubiaceae Fumariaceae Boraginaceae Asteraceae Labiatae Malvaceae Fabaceae Euphorbiaceae Oxalidaceae Papaveraceae Urticaceae Plantaginaceae Portulacaceae Polygonaceae Ranunculaceae Brassicaceae Euphorbiaceae Asteraceae Brassiaceae Solanaceae Asteraceae Asteraceae Zygophyllaceae Leguminaceae Urticaceae Schrophulariaceae Asteraceae Solanaceae Asteraceae A A A A A P B P A A A P A A A A A A A/B A A P A P P A A A A P A A A A P A A A A A A A Arabic قطيفة عين الجمل اقحوان )رجل اإلوز (األبيض أقحوان المروج شوك لبناني مديدة/ لبالب داتورة فربيون الشمس بقلة الملك رقيب الشمس خس بري خبازة مستديرة الورق/ خبيزة فصفصة ي ّ حلبوب سنو ّ ي أو حول أقصيلس عسقولي/ حميضة خشخاش حشيشة الرياح لسان الحمل بقلة بطباط/ عصا الراعي/جنجر الهر ّ كف ّ / حوذان الحقول فجل بري/ فجيلة معروف/خروع كبير شيخة خردل بري عنب الديب لبّين طرخشقون حسك نفَل أبيض او زاحف قراص محرق زهرة الحواشي عنب الديب لبّين WEED IDENTIFICATION Following is a list of plant families common to Lebanon and some identification characteristics for each. SUNFLOWER FAMILY: Flowers in heads, ray, disk, or both types; may be milky often have pappus; often aromatic. Example: Anthemis hyalina (Maywood), Taraxacum officinale (Dandelion). (COMPOSITAE, ASTERACEAE) RHUBARB FAMILY: Sheathing stipules at nodes, sheaths entire or laciniate; often sour. Example: Polygonum aviculare (knotweed). (POLYGONACEAE) PEA FAMILY: Leaves compound; flowers with banner and keel; stipules often present may have tendrils; fruit a legume. Example: Trifolium repens (White clover). (LEGUMINOSAE/FABACEAE). AMARANTH FAMILY: Flowers inconspicuous; plants annual; flowers subtended by sharp bract, no scurfy meal. Example: Amaranthus spp. (pigweed). (AMARANTHACEAE) GOOSEFOOT FAMILY: Flowers inconspicuous; scurfy meal; flowers not subtended by sharp bracts; plants annual. Example: Chenopodium album (lambsquarters). (CHENOPODIACEAE) MUSTARD FAMILY: Petals 4, separate; superior ovary; fruit a silicle or silique, splits into 2 parts; stamens 4 + 2. Example: Sinapis arvensis (Wild Mustard), Raphanus raphanistrum (Wild radish). (CRUCIFERAE/BRASSICACEAE) MINT FAMILY: Leaves opposite; stems square; flowers often irregular; plants often aromatic; fruit 4 nutlets; plant without stiff hairs. Example: Lamium amplexicaule (Henbit). (LABIATAE/LAMIACEAE) GRASS FAMILY: Leaves “grass-like”; hollow stems and solid nodes; inflorescences spike or panicles, awned or no awns. Example: Bromus spp. (Bromes), Avena spp. (Wild oat). (GRAMINEAE, POACEAE). PRESSING PLANT SPECIMENS The following points will aid the student in obtaining durable plant specimens. 1. Place plant specimens between several pages of newspaper. a. Large plants can be bent once or twice so as to fit on the page. b. Expose the underside of several leaves so that characteristics of upper and lower surfaces will appear. c. Roots should be spread to expose them to their utmost. d. Large plant parts such as fruits, stems, and roots should be cut in half or sectioned. e. Seed samples collected should be placed in a cellophane bag and stapled to the page. 2. Place the plant specimen in the press with alternate newspaper sheets and absorbent material (cardboard blotters). a. This aids in absorbing moisture from green samples. b. Change the newspaper and blotters as often as needed. c. The most common mistake is not changing the absorbent material often enough. Moldy and discolored specimens show up rapidly under moist conditions. 3. Plant specimens should be pressed by applying an even, firm pressure. a. This can be accomplished by using a plant press or by applying weight to the top of the plant specimens with books, bricks, etc. b. Do not stack the plant specimens too high. NOTE: The best time to identify a plant is directly after collection. To do so you need handbooks, and equipments such as scissor, knife, digger, and hand lens. If you want to wait 2-4 days, place the whole plant including roots in a plastic bag, seal and keep in the refrigerator. If you want to identify the plant later you need to preserve it by pressing and mounting the specimen. MOUNTING WEED SPECIMENS 1. To obtain long-lasting mounts, the plant should be glued to the sheet (scrapbook page). a. b. c. d. e. 2. Only one specimen should be placed per page, regardless of size. a. b. 3. The glue (such as Elmers) is placed on the glass and thinned with water so it will spread freely. With a small paint brush, spread the glue evenly over the glass. Place the dried plant specimen on the glue-covered glass. After the underside is thoroughly covered with glue, lift the plant from the glass with tweezers and carefully place it on the sheet. Cover the plant and sheet with a piece of waxed paper and place a weight on top so that even pressure is applied while the glue dries. Where collected, the seeding, vegetation, and flowers of one specimen can be placed on one page. When two or more different weed specimens are placed on one page, the student may become confused. When possible, each weed specimen should include a seed sample. a. b. Small cellophane bags, stapled just above the label, will exhibit seed to their best advantage. Place only a few seeds in the bag so studying the shape, size, color, etc., of the individual seed will be easy. 4. Methods for mounting large weed specimens. In many cases weed specimens will be too large to mount on the sheet. There are several solutions to this problem. a. b. Bending Plant Sectioning Plant (Omitting duplicate sections of plant) Steps for Weed Identification Weed identification is a hard task and requires a lot of practice. One approach you could take is to match your unknown weed specimen to the pictures in the Weeds of Lebanon, Weeds of the West, Weeds of the Northeast, Weeds . A good key is the most reliable way to identify a plant. Your Weeds of the West text has a key to the families of all the species in the book and a glossary of several morphological terms. This key assumes a basic knowledge of flower anatomy, specifically, the four floral whorls: sepals, petals, stamens (anther and filament), and pistils (ovary and stigma). Keying plants takes intelligence, persistence, and common sense but most importantly practice. You are not required to master keying in this class. Below are a few points to remember while keying out an unknown plant. 1. To get the general idea of how keys work, key out a plant, the species name of which you already know. Try this with several species. 2. Now for an unknown plant, the first thing that you want to do is look over the plant carefully. Get familiar with leaf shape, presence of hairs, flower shape etc. without the suggestive statements you will be subjected to while reading a key. 3. Now for the book: keys have successive pairs of statements called, leads. The two leads of a pair may be one line or many lines apart but they are numbered or indented alike. Read both pairs. Choose the one that most closely matches your plant and go to where it tells you---to the next pair or the identity. If another pair, then match your plant to the closest lead and continue. 4. Look up any words that your are not absolutely sure about its meaning. Even the slightest misunderstanding could send you into darkness. 5. If you reach a point where neither lead seems plausible, go back and be sure that all your previous choices are sound. If they are, then mark the spot where you are uncertain and go with the least unlikely lead. 6. Never skip steps, even if you see picture or lead farther down the key that seems to match your plant. This could mislead you badly. Keying backwards is not a good habit to get into. For an exercise, select plant samples that will be available in class and go through the following series of questions: plant 1 Do leaves have parallel or netted venation? Is the plant annual (herbaceous) or perennial (e.g.woody)? Are leaves opposite, alternate or whorled? What terms describe leaf shape? What terms describe leaf margins? What terms describe leaf surface? plant 2 plant 3 AGSC 284-Lab One Leaf Shapes of BLWs No 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 Scientific Name Amaranthus retroflexus Anagalis arvensis Anthenis hyalina Capsella bursa-pastoris Chenopodium album Chrysanthunum leucanthemum Cirsuni libanoticum Convolvulus arvensis Datura stramonium Diplotaxis erucoides Erigeron linifolius Erodium romanum Euphorbia helioscopia Galium tricorne Fumaria sp Heliotropium villosum Lamium amplexicaule Malva rotendifolia Medicago hispida 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 Mercurialis annua Oxalis cernua Papaver sp Parietaria judaiaca Plantago major Potulaca olercea Polygonome aviculare Ramunculus arvensis Ricinus communis Senecis vulgaris Sinapsis arvensis Solanum nigrum Sonchus oleraceous Taraxacum officinale Tribulus terrestris Trifolium repens 36 37 38 Urtica vreus Veronica polita Xanthium stramonium Leaf shape/Remarks Obovate or spatulate Ovate Basal rosette ovate Toothed or lobed Ovate to lanceolate Oblong or oblanceolate Sinuate toothed or with weak prickles Ovate, oblong to hastate Ovate Oblong, pinnately, Lobed or toothed Lower l---ovate, Upper l…lanceolate Oblong lobed leaflet Obovate Oblanceolate to linear Oblong to linear Oblong to linear Orbicular Orbicular with cordate bax+slightly lobed Trifoliate, leaflets wedge shaped 3 ovalshaped Ovate Heart-shaped Ovate pinnately lobed Obovate or nearly, Orbicular Obovate or wedge-shaped Lanceolate/ oval Divided into cunate and incised lobe Palately lobed Pinnatifid, dentate, slightly aurided, glabrous Pinnately lobbed, Diamond shaped Ovate and wavy toothed Rucinate-pinnatifid Oblong to saptulate Pinnately compound of4-8 oval leaflets Pinnately compound of obovate-oblong leaflets Ovate Broadly ovate Ovate-cordate AGSC 284 Lab Work One Identification of Broadleaf Weeds St. Name: Date: Specimen No. Scientific Name Family Name Life Cycle Leaf shape/ Remarks