Weed identification and common
weeds associated with sugarcane
Calvin Odero
Everglades REC
Belle Glade, FL
Weed classification
• Weeds come in all growth forms
• May be classified as
– Grass
– Grass-like (sedge)
– Broadleaf
• Forbs
• Succulents
• Shrubs
Dicots
Monocots
Weed classification: life cycles
 Annuals- reproduce by seed only
 Biennial:
 Life cycle completed in two years
 Flowering and fruiting in second year
 Examples: wild carrot, cudweed
 Perrenials:
 Simple- reproduce by seed only
 Creeping- reproduce by seed and vegetative
propagules
Grass identification: vegetative parts
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Leaf blade, blade margin
Collar margin
Midrib
Ligule - structure which
occurs in grasses at point
where the leaf sheath and
blade meet
• Auricle - projections where
sheath and blade meet
• Sheath margins - split with
overlapping margins or
united
Auricle variations
Ligule variations
Sheath variations
Steps 1 to grass ID
• Overall characteristics
– Relative length and
width of first leaf
– Seed characteristics
Step 2 to grass ID
• Stem Type
– Round
– Flat
– Triangular
Step 3 to grass ID
• Ligule Type
– Absent
– Hairy
– Membranous
Step 4 to grass ID
• Blade Type
– Hairy or not (glabrous)
– Midrib prominence and
color
– Margin characteristics
– Presence of auricles
Step 5 to grass ID
• Sheath margins
– Split with overlapping
margins
– United
– Margin with hairs or
not
Step 6 to grass ID
• Root systems
– Perennial with
creeping rhizomes
– Annual
Monocots: grasses and sedges
Grasses
Sedges (Grass-like)
Stems
• Hollow or flattened
• Occasionally solid
• Nodes (jointed)
• Solid
• Triangular (3-sided)
• Without nodes
Leaves
• Parallel veins
• 2 sides
• Parallel veins
• 3 sides
Flowers
• Small
• Inconspicuous
• Small
• Inconspicuous
Example
• Fall panicum
• Yellow nutsedge
Yellow vs purple nutsedge
• Yellow
(Cyperus esculentus)
– Leaves gradually taper
to a point
– Flowers yellowishbrown
– Tubers smooth, round
shaped, at ends of
rhizomes
• Purple
(Cyperus rotundas)
– Leaves abruptly tapers
to a point
– Flowers purple to
brown
– Tubers rough, irregular
shaped, connected in
chains
Purple vs yellow nutsedge
Fall panicum (Panicum dichotomiflorum)
• Most common grass in the area
• Relatively easy to identify
– Stem can be hairy or smooth
– Hairy when young
– Ligule fringe of hairs
– Round stem
– Widely dispersed seedhead
Fall panicum (Panicum dichotomiflorum)
Goosegrass (Eleusine indica)
• Found in many fields
• Low growing
– Very white, flattened
stems
– Looks like it has been
stepped on
– Probably not
competitive
Crabgrass (Digitaria spp.)
• Very wide first leaf
• Initial clumping
growth progressing to
prostrate, tillering
• Visible membranous
ligule
• Can be very hairy, or
hairless, depending
on species
Broadleaf panicum (Urochloa adspersa)
• Relatively prostrate
growth
– Wide leaves with wavy
margins
– Round stems
– Usually dark green in
color
– Very similar to
alexandergrass
Broadleaf panicum (Urochloa adspersa)
Crowfootgrass (Dactyloctenium aegyptium)
• Plants glabrous,
blade margins hairy
• Seed head like a crow
foot
• Bends and roots at
the lower nodes
Bermudagrass (Cynodon dactylon)
• Easy to identify
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Small leaves
Rhizomes and stolons
Mat forming
Ligule fringe of short hairs (hard to see)
• Produces seed and spreads vegetatively
Bermudagrass (Cynodon dactylon)
Sorghum (Sorghum almum)
• ‘Wild oat’
• Closely related to
johnsongrass
– No rhizomes
– Large, membranous
ligule
– Robust plant
Sorghum (Sorghum almum)
Torpedograss (Panicum repens L.)
• Perennial with robust,
creeping, sharply
pointed rhizomes
• Leaf blade stiff and
erect
• Hairs on upper and
lower leaf surface
• Seedheads with stiff,
ascending branches
• Occurs in wet areas
Guineagrass (Panicum maximum)
• Some plants are
extremely hairy, while
others are hairless
• Small plants have
narrow leaves
• Becomes very large
• Highly branched
seedhead
• Round stem
Napiergrass (Pennisetum pupureum)
• Very robust plant
– Forms dense clumps
in fields
– Long, wide leaves with
finely toothed margin
– Up to 12 feet tall
– Seedhead has “bottle
brush” appearance
Paragrass (Brachiaria mutica)
• Prostrate growing,
medium size grass
– Long stems covered
with hairs
• Short hairs on leaf
surface
– Swollen nodes
– Grows in very wet
areas
• Often moves out of
ditches
– Pasture grass in Africa
Dicots: broadleaf plants
• Two cotyledons
• Primary root often becomes a strong tap
root with smaller secondary roots
• Leaves are usually net veined and broad
at the base with a petiole or stalk
Dicots: broadleaf plants
Forbs
Shrubs
Succulents
Stems
• Solid
• Pithy
• Solid
• Growth rings
• Fleshy, thick
• Sharp spines
Leaves
• Net-veined
• Net-veined
• Small, fleshy
• Seldom present
Flowers
• Small or large
• Colored
• Showy
• Small
• Showy
• Showy
Example
• Common
lambsquarters
• Lantana
• Cacti
Broadleaf identification: vegetative parts
• Cotyledons - seed
leaves
• First true leaf
• Older leaves
• Midvein
• Leaf apex
• Margin
• Terminal bud
Steps 1 & 2 in broadleaf ID
• Overall appearance
• Shape of cotyledons
Steps 3 & 4 in broadleaf ID
• Leaf shape
• Leaf arrangement
– opposite
– alternate
– whorled
• Root system
Spiny amaranth (Amaranthus spinosus)
• Most common
‒ Large, upright growth
habit, entire leaves
‒ Very evident spines
located at nodes
Livid amaranth (Amaranthus blitum)
• Can be prostrate or
erect
• Notched leaf tips
Alligatorweed (Alternanthera philoxeroides)
• Common in wet areas
of the EAA
‒ Often spread by
cultivation
‒ Low growing
• Hollow stems when
growing in wet spots
• Opposite leaves
• Small white blooms
Alligatorweed (Alternanthera philoxeroides)
Common lambsquarters (Chenopodium album)
• Common during the
cooler months
• Can be difficult to
control due to waxy
leaf surface that
leaves a white-gray
color
Common purslane (Portulaca oleracea)
• Prostrate, succulent
• Leaves small,
smooth, opposite or
alternate
• Red stems
• Small, yellow flowers
Common ragweed (Ambrosia artemisiifolia)
• Deeply dissected
leaves
• Many hairs on upper
and lower surfaces
• Long seedhead at top
of plant
• Yellow/white flowers
in multiples
Ragweed parthenium (Parthenium hysterophorus)
• Less common than
common ragweed
‒ Common along
canals, ditch-banks,
noncrop areas
• Leaves less deeply
dissected
‒ Divisions don’t go all
the way to the stem
• White flowers
‒ Single, not multiples
American black nightshade (Solanum americanum)
• Becoming more
common in EAA
‒ Alternate leaves
• Usually entire
to somewhat
lobed
‒ Purple fruit
Dayflower (Commelina spp.)
• Common in open
areas, field edges
– Small, probably not
competitive
– Prostrate growth habit
– Parallel veins on
leaves
– Actually a monocot
– Blue flowers
Sources of Weed ID Information
• Web Picture/Taxonomic Sites
– Aquatic, Wetland and Invasive Plant
Particulars and Photographs (U. of Florida)
• Excellent pictures and information
• http://aquat1.ifas.ufl.edu/photos.html
– Weed Identification and Control in Southern
Turfgrasses (U. of Georgia)
• Pictures, descriptions
• http://www.griffin.peachnet.edu/cssci/TURF/turf.htm
• Southern Weed Science Society ID Guide
Sources of Weed ID Information
• Web Picture/Taxonomic Sites
–Many, many more sites
• Many reputable sites
– Many universities
– Other public agencies
• Buyer beware
– Some incorrect information on the web!
If you need help
• Actual plants are best
– Store in plastic bag with damp paper towel
• 8 t0 10 hours
– Press between two pieces of paper
• Change paper often while drying
• Will last indefinitely
– Store on truck dashboard
• PLEASE DON’T!
– Bring several plants
• Flowers and seeds if possible
• Different growth stages if possible
If you need help
• Pictures
– Overall view (growth habit)
– Specific characteristics
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Ligule (grasses)
Hair characteristics
Leaf shape
Root system
– Tubers, rhizomes, stolons
• Stem shape
• Seeds or flowers if available
• Other characteristics we looked at earlier
If you need help
• Additional information
– What type of area
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Dry or wet
Sandy or muck
Cropped area, natural area, disturbed area
History of area (previous crops, etc)
– Actual location
• County, nearby town/city/landmark
Take Home
• Weed ID can be challenging
– Many resources available
• Web is very helpful
– When you need help:
• Provide as much information as possible
– Quality plant sample
– Identify important/unique characteristics
– Site information (wet vs. dry, etc.)
Weed ID manuals
Contact Information
Calvin Odero
University of Florida-IFAS
Everglades Research & Education Center
3200 E Palm Beach Road
Belle Glade, FL 33430
561-993-1509
dcodero@ufl.edu