A Presentation By Mr Allah Dad Khan

3. WEED CLASSIFICATION AND WEED IDENTIFICATIONWEED CLASSIFICATION AND WEED IDENTIFICATION
BYBY
Mr. Allah Dad KhanMr. Allah Dad Khan
Plant Protection Officer NWFPPlant Protection Officer NWFP

4. Weeds
• About 350000 species of plants are known
to man .Of these less than 1% or about
3000 have economic value and only about
300 species are currently used for food
and feed.
• Some plants are termed “weeds” but
apparently not under all circumstances.
• For instance Burmuda grass ( Cynodon
dactylon) is a valueable grass in
pastures,but a very troublesome weed in
crop foields.

5. Definition of weeds
• One 250 years old definition of a
weed reads “a weed is a plant growing
where it is not desired”
• A more relevant definition is “ Weeds
are plants growing in places where,
and at times when, man wants either
some other plants to grow or no
plants to grow atall”

6. Weeds also defined
• weeds are defined as those alien
plant species which are listed
• as “noxious”
• Weed, plant growing where human
beings do not want it to grow

7. Noxious weed
• Noxious weed” means an alien plant or parts of
an alien plant that have been designated by
• rule as being noxious or has been declared a
noxious weed by a local advisory board, and
• meets one or more of the following criteria:
• · Aggressively invades or is detrimental to
economic crops or native plant communities;
• · Is poisonous to livestock;
• · Is a carrier of detrimental insects, diseases,
or parasites;
• · The direct or indirect effect of the presence
of this plant is detrimental to the
• environmentally sound management of natural or
agricultural ecosystems

8. Effects of weeds
• Competition for mineral nutrients.
• Competition for sunlight.
• Competition for water.
• Competition for space
• Parasitism.
• Increase incidence of pests and diseases.
• Reduction of crop quality
• Interferences with cultivation and harvest
operations.
• Clogging of irrigation and drainage canals.

9. Weeds and crop yield
Crop Loss in
yield
Wheat 2-30%
Maize 20-40%
Rice 20-83%
Sugarcane 10-35%
Oilseeds 10-50%
Vegetables 40-80%

10. Classification Of Weeds
• There are many ways on which weeds can be
classified into groups for convenience of
planning,interpreting and recording control
measures against them. Some important
classification of weeds used by weed
researchers in world for different purposes are
as follows:
• Classification according to anatomy of weeds:
Depending upon their cycle, weeds can be
classified as
• Annual
• Biennials
• Perennials

11. Annual Weeds
• Annual weeds: Annual weeds more
commonly complete their life cycle
in one season. An annual weeds can
be either
– Summer annuals
– Kharif annuals e.g. foxtail
– Winter annual e.g. lambs quarter

12. Biennial weeds
• Biennial weeds complete their life
cycle in two years in the firs year
they remain vegetative, and in the
second year they produce flowers
and set seeds.
• E.g. Daucus, Carota, Nulicaulis, etc.

13. Perennial weeds:
Perennial weeds grow for three or
more years.
• E.g. Shallow rooted perennials –
Bermuda grass, Quack grass
• Deep rooted perennials :Johnson
grass

14. Classification according to
cotyledenous character
• a. Monocots
• b. Dicots

15. Classification according
to nature of stem:
• Depending upon the development of
bark tissues on their stems and
branches, weed can be classified as :
• a. Woody e.g Lantana
• b. Semi-woody and
• c. Herbaceous species

16. Classification according
to association :
• It is classified into three classes:
• Season bound,
• b. Crop bound,
• c Crop associated

17. Classification according
to situation:
Depending upon their occurrences there can be nine
important groups of weeds.
• Crop-land weeds.
• Falloland weeds.
• Grassland or pasture weeds.
• Non-cropland weeds
• Aquatic weeds
• Forest and woodland woods
• Lawn and garden weeds.
• Weeds of plantations.
• Orchard and vineyard weeds

18. Classification according
to origin of weeds:
Many of weeds in India originated in
some other part of the world.
For e.g. Convolvulus sp –Eurasia,
cyperus –Euphorbia,-Europe, Lantana
–Africa

19. Classification according to soil:
• Of the several variable of soil, soil
pH is implicated most frequently with
the distribution of weed species.
Weeds, such as red sorrel, corn
sporry and bracken tend to
comminute with weed flora on saline
and alkali soils.

20. Classification according
to climate:
• Temperature, rainfall, air quality,
humidity and solar energy have
pronounced effect on the
distribution of weeds. One could
classify weeds as
• hillside weeds,
• weeds of plains,
• temperate weeds,
• tropical weeds,etc.

21. Facultative and obligate
weed:
• Facultative weeds are those weeds
that grow primarily in wild
communities but often escape to
cultivated fields. E.g. Opuntia Spp.
Obligate weeds on the contrary,
occur only in cultivated or otherwise
disturbed land.
• For e.g.: Field bind weed.

22. Noxious weeds:
• Noxious weeds is a plant arbitrarily
defined as being especially
undesirable troublesome and difficult
to control for e.g. Chicory, thistle,
bermuda grass (hariyali

23. Weed Identification
• Annual grasses
• Perennial grasses
• Broadleaf weeds
• Miscellaneous

24. Annual grasses
• Goosegrass
• Eleusine Indica
• Rabgrasses
• Digitaria spp.
• annual bluegrass
• Poa annua
• yellow foxtail
• Setaria lutescens (glauca)

25. Goosegrass or Silver Crabgrass
(Eleusine indica)
• It is a warm season annual member of the
Grass family (Poaceae) that reproduces by
seeds, usually emerging a few weeks after
crabgrass. Goosegrass is a coarse, bunch-type
grass that forms a basal rosette of prostrate
to occasionally upright flattened stems up to 2
feet long. The stems do not root at nodes. The
root system is fibrous, and the lower portions
of stems near the base are silver or white. The
leaves of goosegrass are dark green, hairy
near the base, and smooth and keeled below.
They grow up to 12 inches long and 1/3 inch
wide and are either flat or folded. Goosegrass
flowers are 2 to 10 flattened, finger-like
spikes that each resemble a zipper

26. Goosegrass or Silver Crabgrass
(Eleusine indica)

27. Yellow Foxtail (Setaria glauca)
• It is a warm season annual member of the Grass
family that reproduces by seeds. Seeds germinate
at temperatures between 68 and 95 °F. Yellow
foxtail forms a coarse, upright or prostrate,
bunch-type grass. It usually branches at the base
and may root at lower nodes. Growing up to 4 feet
tall, yellow foxtail emerges from a shallow,
fibrous root system and normally has flattened
stems that are reddish near the base. Leaves of
yellow foxtail are flat, smooth, and with margins
that are somewhat rough.

28. Yellow Foxtail (Setaria glauca)

29. Perennial Grasses
• Quackgrass
• Agropyon repens
• creeping bentgrass
• Agrosis palustris
• tall fescue
• Festuca undinacea
• Nimblewill
• Muhlenbergia shreberi

30. Broad leaf weeds
• common yarrow Achillea millefolium
• wild garlic Allium vineale
• shepherd's purse
» Capsella bursa-pastoris
• mouse-ear chickweed Cerastium vulgatum
• Thistles Cirsium spp.
• prostrate spurge Euphornia
supina
• ground ivy Gleochoma
hederacea
• Henbit Lamium amplexicaule
• roundleaf mallow Malva neglecta

31. Broad leaf weeds
• yellow woodsorrel Oxalis strictabroadleaf
plantainPlantago major
• buckhorn plantain Plantago lanceolata
• prostrate knotweed Polygonum aviculare
• common purslane Portulacea oleracea
• red sorrel Rumex acetosella
• curled dock Rumex spp.
• common chickweed Stellaria media
• Dandelion Taraxacum
Officinale
• white clover Trifolium repens
• Violets Viola spp

32. Common Yarrow (Achillea
millefolium)
• Also known as milfoil, thousandleaf, or
woundwort, it is a perennial member of
the Aster family (Compositae) that
reproduces by seeds or short
underground rootstocks. Upright
common yarrow stems emerge from
taproots to form a dense mat under
close mowing. The stems are usually
not branched; are smooth to densely
covered with long, soft or woolly
grayish-green hairs and are 4 to 24
inches tall. The tops of the stems may
branch. The alternate, finely pinnately
dissected and fern-like leaves are soft
and covered with hair. The basal
leaves longer than those growing on
stem; stem leaves are 3 to 8 inches
long. The flowers develop in falt-
topped clusters at the top of
branches. There are white or pink ray
flowers and yellow disk flowers.
Flowering occurs in June to October.
Common yarrow often occurs in poor,
gravely, droughty, and infertile soils
and does not compete well with turf on
rich soils. It is wear and drought
tolerant

33. Wild Garlic (Allium
vineale)
• It is a cool season perennial member of the
• Lily family (Liliaceae) that reproduces by seeds, aerial bulblets,
and underground bulblets. Most reproduction in northern states is
asexual. Beginning growth early in the spring, wild garlic develops
from a bulb into an upright, grass-like plant with an onion or garlic
odor. Stems can grow to more than 3 feet. The leaves of wild
garlic are 2-ranked, slender, hollow, nearly round; and attached
halfway down on waxy stem. The inflorescence is an umbel, 1 to 2
inch diameter. The flowers are small, greenish-white, and found on
stems above the aerial bulblets.
• Flowering occurs during May and June.
• Wild garlic is commonly found in
• poorly-drained, fine-textured,
• fertile soils and thin turf areas

34. Shepherd's Purse
(Capsella bursa-pastoris)
• It is a annual or winter annual
member of the Mustard
family (Cruciferae) that
reproduces by seeds.
Shepherd's purse emerges
from a thin, branched taproot
to form a rosette of leaves
and thin, erect, usually
branched stems to 24 inches
tall. The stems are usually
covered with grayish hairs.
Forming a rosette, the basal
leaves are simple, 2 to 5
inches long, and variably
lobed, serrated, or divided.
Leaves on the stems are
alternate, 1 to 4 inches long,
and are usually toothed or
lobed. The base on these
leaves are ear-like and clasp
or rap around the stem.

35. Mouse-ear Chickweed (Celastium
vulgatum)
• It is a perennial member of
the Pink family
(Caryophyllaceae) that
reproduces by seeds and
occasionally by creeping stems
that may root where they
touch the soil. Mouse-ear
chickweed have shallow,
fibrous roots. The mat-
forming plants grow up to 20
inches tall and have weak,
hairy, spreading stems.
Mouse-ear chickweed leaves
are opposite, dark green, very
hairy, and less than 1 inch long
and up to 1/2 inch wide. They
are without petioles and oval
to elliptically shaped. The
small, white flowers have five
white petals that are notched
at the tips. Hairy, leafy sepals
are borne beneath the

36. Bull Thistle (Cirsium vulgare) and Canada
Thistle (Cirsium arvense)
• They are members of the Aster family (Asteraceae). Bull thistle is
a biennial that reproduces by seed, and Canada thistle is a
perennial that reproduces by seed and rhizomes. Bull thistle forms
large, coarse plants with spiny leaves, large taproots, and stems
that are heavy and branched at top and hairy when mature. Canada
thistle also forms large, coarse plants with spiny leaves. The large,
rhizomatous underground system form stems that are grooved and
branched at top, hairy in youth, smooth when mature. Bull thistle
leaves are deeply-lobed, spiny above and below, and pubescent
beneath. The leaf base joins stem resulting in winged appearance

37. Prostrate Spurge (Euphorbia
supina)
• It is a warm season member
of the Spurge family
(Euphorbiaceae) that
reproduces by seeds.
Germination occurs when soil
temperatures warm to 60 to
65 oF and can continue as soil
temperatures climb to more
than 90 oF. Prostrate spurge
develops a central taproot
from which prostrate stems
that form a flat, extensively
branched mat up to 2 feet in
diameter. The stems exude
milky sap when broken. Leaves
of prostrate spurge are
opposite, small, oval, and up to
3/5 inch long. They are
sometimes purple-spotted
and/or hairy. The petioles are
short. Prostrate spurge
flowers are very small and

38. Ground Ivy (Glechoma
hederaceae)
• Also known as creeping Charlie, it is a perennial member of
the Mint family (Lamiaceae) that reproduces by seeds and
root pieces. It may form patches in turf as it creeps on
square stems that can grow up to 2 1/2 feet long,
sometimes rooting at the nodes. Occasionally the stems
grow in an ascending fashion. Leaves of ground ivy are
opposite, round to kidney shaped, and 1/2 to 1 1/2 inches in
diameter.

39. Roundleaf Mallow (Malva
neglecta)
• It is also known as common mallow, cheeses, dwarf mallow, running
mallow, malice, round dock, and button weed. It is an annual or
biennial member of the Mallow family (Malvaceae) that reproduces
by seed. Emerging from a short, straight taproot, roundleaved
mallow develops stems up to 12 inches long. The hairy stems are
horizontal or upright and may be branching at base. The stems do
not root as they touch the ground. The simple, alternate leaves of
roundleaved mallow are round to heart-shaped usually with 5 to 9
shallow lobes or rounded teeth. They are up to 2 1/2 inch across
and hairy on both surfaces. The petioles are also hairy and up to 4
inches long.

40. Black Medic (Medicago lupulina)
• It is an annual, biennial or perennial member of the Legume family
(Fabaceae) that reproduces by seeds. Black medic is shallow
rooted with multi-branched slender, prostrate, slightly hairy
stems spreading 12 to 24 inches. The alternately arranged, dark
green leaves are compound with three, oval leaflets. The center
leaflet is stalked and the side leaflets occur close to the stem.
Leaves are sparsely hairy and the leaflets 1/5 to 3/5 inch long.
The 1/8 to 1/6 inch long bright yellow flowers are clustered on
short stems that emerge from the leaf axils. Each cluster is
approximately 1/2 inch long, round, and comprised of up to 50
individual flowers. Flowering occurs April to October

41. Knotweed (Polygonum
aviculare
• It is also known as knotgrass. It is a warm season member of the
Polygonaceae (Buckwheat Family) that reproduces by seeds. During
early spring, knotweed resembles a grass with long, dark green
leaves when germinating. Later, it forms a flat mat up to 2 feet in
diameter. It has slender, wiry stems; and emerges from a taproot.
There are papery sheaths at each node that give stems a knotted
or swollen appearance. The leaves are alternate, small, narrowly
oval, dull bluish-green, and up to 1 1/4 inches long and 1/3 inch
wide. Its flowers are small, borne in clusters in leaf axils. The
buds are purplish opening to white to yellow flowers during June
through October

42. Common Purslane (Portulacca
oleracea)
• It is also known as wild portulaca. It is a warm season annual
member of the Purslane family (Portulacaceae) that reproduces by
seeds or rooting stem pieces. Common purslane emerges from a
heavy taproot, to develop succulent, smooth, fleshy stems that are
usually purple-red and may root at lower nodes. these many
branched stems reach up to 24 inches long and grow in a prostrate
fashion to form mats. Common purslane leaves are alternate to sub
opposite, oval shaped with the widest point beyond the leaf's
middle. Growing up to 1 1/4 inch long, the thick, fleshy leaves are
often clustered near the ends of branches. They are smooth and
without leaf stalks. The yellow flowers of common purslane are
borne individually in the leaf axils or clustered at end of branches.
There are five petals. The fruit is a globular capsule. Flowering
occurs in July through September.

43. Curly Dock or Curled Dock (Rumex crispus)
• It is a perennial member of the Buckwheat family (Polygonaceae)
that reproduces by seeds and occasionally root pieces. Curled dock
develops a dense rosette of 6 to 12 inch-long leaves that emerge
from a large, fleshy, somewhat branched yellow-orange taproot on
a short crown. At flowering, the inflorescence develops at the top
of a stem that can reach 4 1/2 feet tall. The dark green leaves are
simple with a heart-shaped base. The leaf edges are wavy or curly.
Leaves on the stem are alternate and have short petioles.

44. Dandelion (Taraxacum
officinale)
• It is a cool season perennial of the Aster family (Asteraceae) that
reproduces by seeds and root pieces. Dandelions emerge above a
long, sturdy taproot to form basal rosettes of narrow, deeply
lobed leaves. These leaves are 2 to 10 inches long and up to 2 1/2
inches wide. They have jagged lobes that point back towards stem.
Dandelion inflorescences are yellow, up to 2 inches in diameter,
and appear to be solitary. They are borne on hollow stems that can
grow up to 20 inches long, and held above the foliage. The
inflorescences ripen to become round "puffballs" of wind-
dispersed seeds. Flowering period is from early spring to late fall.
Dandelions occur in most lawns throughout the growing season,
especially thin turf areas

45. Field Bindweed:
Convolvulus arvensis
• Weed Description: A perennial trailing or climbing weed with
white morningglory-like flowers that may reach 3 1/3 feet in
length. Field bindweed is primarily a weed of nurseries,
agronomic crops, and fencerows that can be found throughout
the United States Weed Description: A perennial trailing or
climbing weed with white morningglory-like flowers that may
reach 3 1/3 feet in length. Field bindweed is primarily a weed
of nurseries, agronomic crops, and fencerows that can be
found throughout the United States

46. Miscellaneous
• yellow nutsedge Cyperus
esculentus

47. Yellow Nutsedge (Cyperus esculentus)
• Also known as yellow
nutgrass. It is a perennial
member of the Cyperaceae
(Sedge Family) that
reproduces by seeds and
tubers (nutlets) that form
at ends of rhizomes.
Individual yellow nutsedge
plants have upright, grass-
like leaves that emerge
from a fibrous root system
and scaly rhizomes. These
leaves emerge from the
plant's base, are 3-ranked,
grass-like, and light yellow-
green. They are 1/8 to 1/2
inch wide, up to 3 feet
long, and have parallel veins
with a prominent midvein

48. Main weeds of world in
order of priority
S.no Botanical name Local names
1. Cyperus rotundus Nut grass, purple nutsedge
2. Cyondon dactylon Bermuda grass, couch grass,star
grass
3. Echinochloa crusgalli Barnyard grass
4. Echinochloa colonum Awnless barnyard grass
5. Eleusine indica Crowfoot grass, goosegrass, wild
finger millett,
6. Sorghum halepense Aleppograss, jhonson grass
7. Imperata cylindrica Sword grass, cogon grass.
8. Eichhornia crassipes Wateryhyacinth

49. Main weeds of world in
order of priority
S.no Botanical name Local names
10. Chenopodium album Fathen, goose foot, lambsquarter
11. Digitaria sanguinalis Hairy or large crab grass.
12. Convolvulus arvensis Bind weed, field bind weed
13. Avena fatua Wild oats
14. Amaranthus hybridus Pigweed, smooth amaranthus
15. Amaranthus spinosus Prickly amaranth, spiny pigweed
16. Cyperus esculentus Nuttgrass, water grass, yellow
nutsedge.
17. Paspalum conjugatum Sour grass, sour paspalum
18 Rottboellia exaltata Guinea foelgrass, itch grass, Raoul

50. Seed production of some
common weeds
# Weed species English name Average number of
seeds per plant
1. Amaranthus hybridus Pigweed, smooth
amaranthus
196000
2. Chenopodium album Fathen, goose foot, 72000
lambsquarter
3. Cascuta species Ddder 16000
4. Eleusine indica Crowfoot grass,
goosegrass, wild
finger millett,
41200
5. Portulaca oleracea Pigweed purslane 193000

51. Duration of weed seed
dormancy in the soil
Name of
weed
English name Viability of
some weed
seeds in years
Stellaria
media
Common chick
weed
30
Capsella
bursa
pastoris
Shepherds purse 35
Chenopodium
album
Rough pigweed 40
Rumex
crispus
Curled dock 80