Download Pressing Plant Specimens

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