Transcript Weed ID Glossary PPT - Weed Identification and Control Databases

WEED
IDENTIFICATION
- TERMINOLOGY
C. Shumway
B. Scott
THIS IS A GLOSSARY OF TERMS USED IN THE IDENTIFICATION OF
WEED SPECIES. PROPER IDENTIFICATION IS A KEY COMPONENT ON
THE EFFICIENT USE OF WEED CONTROL MEASURES.
ON THE CONTACT INFORMATION AND RESOURCE PAGE THERE ARE A
NUMBER OF SITES THAT HAVE EXCELLENT IDENTIFICATION KEYS
BASED ON THESE CHARACTERISTICS.
CONTACT INFORMATION AND RESOURCES
THIS IS FOR GENERAL USE; REMEMBER TO USE ALL OTHER RESOURCES
AVAILABLE TO EVALUATE THE IDENTIFICATION OF A WEED SPECIES.
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WEED IDENTIFICATION GLOSSARY - A - Le
ASEXUAL REPRODUCTION –
BULB
JOINTING & BOLTING
LEAF ARRANGEMENT–
RHIZOME
ALTERNATE
ROOT
OPPOSITE
STOLON
ROSETTE
TUBER
WHORLED
COTYLEDON
GROWTH HABIT
LEAF MORPHOLOGY – GENERAL
BLADE
DECUMBENT
COMPOUND
ERECT
INTERNODE
PROSTRATE
NODE
ROSETTE
SHAPE
GLABROUS
SIMPLE
WEED IDENTIFICATION GLOSSARY - Le - Z
LEAF MORPHOLOGY – DICOT
LIFE CYCLE
LEAFLET
PUBESCENCE
OCREA
ROOT
PETIOLE
ADVENTITIOUS
STIPULE
BRACE
TENDRIL
TAP
THORN (SPINE)
LEAF MORPHOLOGY – MONOCOT
AURICLE
SEEDLING EMERGENCE
EPIGEAL
HYPOGEAL
COLLAR
STEM
LIGULE
STEM SHAPE
SHEATH
TILLER
LEAF VENATION –
NET
PARALLEL
ASEXUAL PROPAGATION - A major area for the growth and
identification of weed species is the natural production of
vegetative plant structures that have the capacity to produce new
plants. Asexual propagation is the best way to maintain some
species. Many of these vegetative structures are modified stems
and include structures produced below the soil line (bulbs,
rhizomes, roots, and tubers) and above the soil (stolons). Many of
these serve as food storage areas for the plant. True roots,
although less prevalent, are also found in several wee species.
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BULBS: consist of
very short stems with
closely packed leaves
arranged in concentric
circles around the
stem. The leaves are
swollen with stored
food e.g. wild onion
and wild garlic. A
terminal bud will
produce the flowering
shoot and the lateral
(axillary) buds will
produce new plants.
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RHIZOMES - are stems which grow horizontally under the ground. in some cases the
underground stems are swollen with food reserves. The terminal bud turns upwards to
produce the vegetative shoot. Examples below include Johnsongrass and sedge.
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One type of
asexual
propagation is a
‘true’ root system
producing
adventitious
shoots. It is
found in the
nightshade
(solanaceae) and
the asteraceae
family [typically
in the thistle
group]. New
plants emerge
from rootstocks
buried below the
soil surface.
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STOLON - is a horizontal stem that can produce new adventitious roots. A term
that is also used is a runner.
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TUBERS - Are thick, underground stems that develop at the end of rhizomes. The
tuber has all the parts of a normal stem, including nodes and internodes. Below
is the production of tubers from a rhizome on a sedge plant.
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COTYLEDON (SEED LEAVES):
Function of this structure is
primarily storage of reserves
for use during germination;
tissue will be photosynthetic
with the duration of this
function being variable based
on the species.
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COTYLEDON
SHAPES
GROWTH HABIT
– DECUMBENT :
The term used
to describe the
growth of the
stem when they
are prostrate
with leaves
growing
upwards.
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GROWTH HABIT - ERECT
The term used to describe the upright growth of the stem
and leaves.
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GROWTH HABIT –
PROSTRATE : The
term used to describe
the growth of the
stem when they are
flat on the ground.
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GROWTH HABIT – ROSETTE: The term used to describe the growth of the stem
when the internodes are not elongated (compressed).
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PUBESCENCE: Plants that
have trichomes on any plant
part (leaf, stem, petiole, etc.).
These trichomes can be
dense to sparse with the
location being very specific
within a weed species.
GLABROUS: Without any
trichomes.:
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JOINTING – A term used to describe the
elongation of the internode in monocots; allows
for a separation of the nodes of the plant.
NODE
INTERNODE
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BOLTING - A term used to describe the
elongation of the internode in dicots
which typically have a rosette type of
growth; allows for a separation of the
nodes of the plant. Typical in biennials.
LEAF ARRANGEMENT – ALTERNATE:
Has one leaf which emerges per node
on the stem.
LEAF ARRANGEMENT – WHORLED: Has more
than two leaves emerging from the same node
on the stem.
LEAF ARRANGEMENT – OPPOSITE;
Has two leaves which emerge per
node on the stem.
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LEAF BLADE – A general term used to describe the part of the leaf that is
photosynthetic.
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COMPOUND LEAF – A leaf that has
multiple leaflets; the point of attachment
to the stem is still a petiole but the
leaflets are attached to a structure called
a rachis.
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SIMPLE LEAF – Has a single blade
and is attached to the plant by a
petiole.
NODES – Are enlarged regions of
stems that are generally solid and
where leaves are attached; will also
have axillary buds for continued
vegetative and reproductive
growth.
INTERNODES - The region of a
stem between two successive
nodes.
STIPULE - Is an appendage of the
young leaf and is attached to the
base of the petiole.
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LEAF SHAPES
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LEAFLET – A term
used to describe
the individual
blades on a
compound leaf.
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OCREA - A unique structure that we find in in some dicots. They are described as fused
stipules that form a sheath around the stem. These are found within the circle with (a) curly
dock (Rumex spp.) and (b) smartweeds (Polygonum spp.).
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PETIOLE: The stalk that attaches a leaf blade to a stem of a simple leaf. Compound leave’s
point of attachment to the stem is still a petiole but the leaflets are attached to a structure
called a rachis (the main axis of a compound leaf).
PETIOLE
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TENDRIL - Is a slender, coiling
modified leaf or stem which
aids in the support of the
shoot system.
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THORNS (SPINES) - Are
found on various plant
parts and are typically
hard structures with
sharp, stiff ends. The
terms are used
interchangeably, but
thorns are structures
typically derived from
shoots, whereas spines
typically develop from
leaves.
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ILLUSTRATIONS OF THE VARIOUS COMPONENT ASSOCIATED WITH THE COLLAR
REGION IN A MONOCOT AND MAY INCLUDE THE LIGULE , AURICLE , AND THE
SHEATH
LIGULE
LIGULE - is a structure on the
inside of the collar. A ligule is
either membranous, hairy or
absent.
AURICLE
AURICLES - are claw like
appendages found at the
junction of the leaf blade
and the leaf sheath.
SHEATH
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TYPES OF
SHEATHS
LIGULE
AURICLE
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SHEATHS - Are
tubular extensions
of a grass leaf that
surrounds the
stem.
classifications are
based on the
general
appearance and
can be
overlapping, split,
or united.
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NETTED-VEINED
LEAVES – These
leaves have a few
prominent veins from
which a large number
of minor veins arise.
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PARALLEL-VEINED
LEAVES- These leaves
contain veins about
equal in size and running
parallel. Growth of grass
leaves takes place by
elongation near the base.
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LIFE CYCLE
ANNUALS- Plants that complete their entire life cycle (from seed to seed)
in a single growing season.
BIENNIALS- Require two growing seasons to complete their life cycle.
Vegetative growth occurs during the first season (vernalization occurs
during the winter), and flowering and fruiting occur in the second
season.
PERENNIALS- Have an indefinite life period based on species and
environment. They differ from other classifications in that they do not
cease growth after reproduction.
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ROOTS, ADVENTITIOUS:
Refers to roots arising
from areas not related to
the true root (product of
the radicle).
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ROOT, TAP: The
descending axis of a
plant derived from the
radicle.
ROOT, BRACE – A type
of adventitious root that
grows from the stem
above-ground and serves
for support of the plant.
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STEM- The main body of a
plant, usually the ascending
axis, whether above or below
the ground in opposition to
the descending axis or root.
Stems, but not roots, produce
nodes and axillary buds.
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STEM SHAPE - Varies in plant types. The classifications include: round, triangular
(typical of sedges, oval, and square (typical of the mint family.
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TILLER (OR TO DESCIBE THE PROCESS IS
TILLERING) - is the production of additional
stems from the activity of the axillary buds.
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ILLUSTRATION OF VARIOUS COTYLEDON SHAPES>
Linear
round
oblong
lanceolate
ovate
spatulate
kidney
RETURN
oval
butterfly
EMERGENCE TYPES
In hypogeal germination, the epicotyl or plumule
will grow and emerge above the soil surface.
However, the cotyledons and the first node will
remain below the soil surface. Typical of
monocots and cool-season dicots.
In epigeal emergence, we have the epicotyl,
cotyledon, and the first node moving above the
soil surface. Typical of most dicots.
plumule
coleoptile
cotyledon
First node
hypocotyl
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This is a link to the MP44 published by the UA/CES. This contains information
on labeled herbicides in the state of Arkansas. This publication also contains
information of resistance management, spray information and REIs.
MP44
This is a link to the International Survey of Herbicide Resistant Weeds. This
website contains current information on herbicide resistance weeds and their
management.
ISHRW
These are links to several websites that have information on weed species
identification.
AgWeb Online Field Guide - Weeds
University of ArkansasWeed ID
For further information or comments, please contact the following personnel:
Cal Shumway, Agronomist
COAT, Arkansas State University
State University, AR 72467
Email: [email protected]
Bob Scott, Weed Scientist
Lonoke Agricultural Center
Lonoke AR 72086
Email: [email protected]
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