How to Identify Weeds

Three Parts:Identifying Grass and Grass-Like WeedsIdentifying Broad-leaf WeedsIdentifying Woody Weeds

Weeds are considered invasive plants, however they are actually just unwanted plants that are found in gardens, lawns, fields, ditches, pastures, or anywhere else people don't want a certain species of plant to exist. Not all weeds are invasive species, many plants considered as "weeds" are, depending on the location, native to that particular location they happen to grow in. For example, in North America some common "weeds" that are found in gardens that are actually native include hemp nettle, stinging nettle, lamb's quarters, shepherd's purse, common chickweed, and Bicknell's geranium to name a few. Other weeds are truly invasive species that have spread from gardens or other locations that have originally deliberately grown them as ornamentals or for medicinal/food purposes. These include baby's breath, common tansy, spotted knapweed, Canada thistle, dandelion, smooth brome grass, Kentucky blue grass, quackgrass, cheatgrass, and many others.

Essentially, however, a "weed" is considered an invasive plant, regardless of its nativity or lack-thereof to its location, that competes with other cultivated ornamental or edible plants for nutrients, sunlight, moisture, and leaf area to grow. There are billions of species of plants in the world, and a surprisingly large number of those can be considered a weed in any setting of human habitation.

Generally there are three categories of weeds found: Grass and grass-like plants, Broad-leaf plants, and woody plants. The three sections below helps you identify which is which by showing the basic characteristics that identify each. Each section also highlights some of the more common weeds found across North America, although a full list of weeds found in your area will not be available here. Local gardening books or government or university extension sources will help you identify both the weeds and invasive plants common to your area. Many plant identification books with pictures have also been published to help identify the many species of plants that can be found in one or several locations. Many of such books also have a dichotomous key (also unavailable here) to help you further in narrowing down the possibilities of finding out what a particular plant may be that shouldn't be growing in your garden or flower bed.

Part 1
Identifying Grass and Grass-Like Weeds

  1. Image titled Identify Weeds Step 1
    Understand the characteristics of a grass and grass-like plant. All grasses and grass-like plants in the family Graminaceae (or Poaceae) are easily identified by their long, narrow leaves with parallel veins. As they mature they form a "stem"--which is not a true stem like with woody- and broad-leaf species of angiosperms and gymnosperms--or a culm that ends with an inflorescence or seed-head with multiple small, green, inconspicuous flowers.[1]
    • Grasses and grass-like plants belong in a large group called Monocotyledons. Besides those in the Gramineae family, there are many other plants that resemble a grass, because of the leaf structure. The differences begin with flowering characteristics. Orchids, irises, lilies, cattails, bur-reeds, and arrow-grasses are such monocots, the first three have showy, non-petal-like flower parts, and the latter are tightly condensed flowers without the typical lemmas, glumes, and florets that form a spikelet, or even the perigynium, typical of sedges and most rushes.
  2. 2
    Find or locate a weed that would likely be a grass or grass-like weed. Using the basic identifying characteristics described in the above step, find a plant in your garden or flower bed that obviously shouldn't be growing in there and looks suspiciously like a grass.
  3. 3
    Examine the plant. Grasses have several parts: Leaves or blades, stems, collars, and inflorescences. Below ground, they often have fibrous, spreading roots. Many weed grasses are able to spread with production of tillers from the "mother plant" which sends out multiple spreading rhizomes. Quackgrass is especially notorious for this. There are also bunchgrass grasses, but these are not the kinds of grasses likely to become weeds due to their inability to spread out quickly like with rhizomatous, sod-forming grasses such as Quackgrass and Kentucky Bluegrass.
    • Leaves and stems (culms): Grasses in their vegetative stage will be mainly leaves, with no visible stem. The true stem of grasses is only 1 to 2 millimeters long, and at the very base of the plant. This is also where the growth point or apical meristem is located, and where the plant's leaves and inflorescence originate from. Most species' leaves emerge rolled, and they all emerge from the base of the plant, one leaf blade at a time.
      • Leaves of grasses are long, slender, and narrow with parallel veins. Tips of leaves vary from boat-shaped tips (typical of Poa species like Kentucky Bluegrass), to sharply pointed. Leaves themselves range in characteristics including parallel sided, needle-like, twisting, tapered, or constricted at the base. [2] Leaves can also be stiff, lax, flat, rolled, or even folded. They may have a waxy coating, or glossy on either sides. You'll need to pay attention to all potential characteristics that a leaf blade may or may not have, including length and width.
      • Most culms of grasses are rounded, though several species can also be elliptical or flat [3]. While the crown is the inflorescence, the entire culm is hollow except where leaves join the culm, forming the. the collar. The collar, aside from the blade consists of the node, sheath, auricles, and ligule. The collar is the best way to identify a grass plant if an inflorescence has not emerged. While the node is the point where the next leaf begins, the culm of the grass elongates as the plant pushes up the seed head from inside the hollow culm, and the space between each leaf blade lengthens as the plant reaches maturity.
    • Inflorescence:The inflorescence that eventually emerges up through the culm and which forms the last section of the entire plant, hence the "crown," is essentially a grouping of several floret units called spikelets. Each spikelet is arranged on a main axis that may be stalked or stalkless. The stalked spikelets may be branched or not branched. Thus, grass inflorescences come in three different arrangements: spikes, racemes or panicles, respectively.
      • Spikelets: Each spikelet has two glumes, which are simply flowerless bracts below or subtending the spikelet, and may be larger, smaller, or equal to the length of the bottom-most florets. A spikelet may have as few as one floret or as many as seven or eight in some species. Some spikelets may have one or more awns (a long appendage sticking out from a floret), and "callus hairs" at the base inside the glumes. Flowering spikelets have anthers exposed out to the wind and insects to disperse pollen, and these tiny anthers are often yellow in color. Once flowering has finished, seeds form in the spikelet, not in a pod or fruit like with many broad-leaved weeds mentioned below.
    • Sedges are also common weeds found in lawns and gardens and in various conditions, from very wet to dry areas. [4] They are not part of the Gramineae family, but they share many attributes with grasses. Some sedge weeds are rare in some areas compared with others, for instance sedge weeds are much more common in Florida, USA than in Alberta, Canada. That said, there are far more species of grass weeds than sedge weeds in all of North America[5], which may explain their rarity in many locations.
      • Sedges can be identified by feeling for a three-sided or triangular stem--often thick forming from a basal, fibrous and often rhizomatous root stem. All sedges have an erect, three-sided stem with aerial inflorescences at the top and basal leaves remaining at the base.
  4. 4
    Examine the grass-like weed. Using the information provided above as well as that from an accompanying weed or plant identification book, look at the various anatomical features of the plant to help you determine the name of that particular plant.
    • Note that not all grasses nor grass-like species can be identified using the presence of inflorescences or seed-heads. Many grass weeds that should be eliminated from the garden or flower bed as early as possible are still in their vegetative stage, and an ID on them cannot wait until they finally flower. This is especially true in the spring when weeds tend to be most prolific and are in greatest competition with newly planted garden plants or germinating seedlings.
      • For cases like these, it's highly recommended to look at the features of the collar region of the plant. As mentioned above, look for the ligule, auricles, and the shape characteristic of the sheath. (For definitions of some of the terms used here, please refer to Tips below.)
  5. 5
    Make an identification guess on the species or common name of the plant. Most who are new to identifying plants feel most comfortable referring to the common name of a plant, and choose to learn the species' scientific, Latin or Greek taxonomic names later.
    • However please note that it's very common for a single plant to have more than one common name, depending on location and the language of those referring to a particular plant, so use of common names exclusively in identifying any plant, weed or not, is discouraged especially in the world's scientific community. This is because many plants have one taxonomic name, and that one taxonomic name is often the name that is easily recognized in all languages in by many people in all regions.

The Grass and Grass-like Weeds

Thus, with the list of grass weeds mentioned below, both the North American common name and the world-wide accepted scientific name are used along with the physical descriptions of each plant.

  • Jointed Goat Grass (Aegilops cylindrica):
    Image titled 2009.07.13_15.03.57_IMG_0501
    An annual that resembles wheat. Erect stem 40 to 80 cm tall, roots fibrous. Hairy auricles clasping the stem. Leaves have even-spaced hairs at 90-degree angle to the edge. Inflorescence a narrow spike with long awns, glumes on upper spikelets with 2 to 4 flowers per spikelet.
    • Genetically related to winter wheat, and can often hybridize with it. Contaminates wheat stores since seeds appear similar in size to wheat seeds. Originated from western Asia and southeastern Europe.
  • Quackgrass (Agropyron repens):
    Image titled Agropyron repens
    A perennial, upright, creeping-rooted plant, with long extensive rhizomes. Grows 4 to 5 feet (~1.2 metres) tall. Leaves flat, 6 to 20 cm long, 4 to 10 mm wide; sparsely hairy above with evenly spaced hairs extending from blades, hairless below. Sheath open with overlapping margins, soft hairs below; auricles often clasping, 3 mm long and pointed. Ligule short (~1 mm long) and papery. Inflorescence is single and wheat-like (a single spike) 5 to 25 cm long; spikelets set edgewise to the stem, with 2 to 9 florets.
    • Introduced from Europe in the late 17th century. Quackgrass found and can severely infest fields and lawns. In severely affected fields, rhizomes can take up as much as 7 to 9 tonnes per acre. They produce a chemical that can suppress growth of other competing plants. Affects the yield of all cultivated crops, and often a contaminant of cultivated seed.
  • Wild Oats (Avena fatua):
    Image titled Wild oats
    Annual that resembles oats. Tufted plant (3 to 5 stems from base), to 1.5 m tall, with extensive fibrous roots; stems with dark-coloured nodes. Leaves flat, up to 60 cm long and 4 to 18 mm wide; twisted counter-clockwise. Open sheath with transparent and slightly hairy edges; few long white hairs found at base of blade. Papery ligule irregularly torn, 2 to 5 mm long. Auricles absent. Inflorescence an open, drooping panicle. Spikelets large, composed or 2 to 3 flowers, 2 to 2.5 cm long, and occur singly at end of branches. Glumes smooth with fine lines; lemmas have twisted and slightly bent awns. Seeds elliptical, light yellow to black, 1 cm long, numerous brown hairs at base, with twisted, bent, dark brown to black awn 2 to 5 cm long.
    • Most serious weed in North America, with potential to reduce crop yields by 50% due to docking losses, lower crop grade and quality, and allelopathic tendency to inhibit germination of other plants, especially as straw residue.
  • Smooth Brome grass (Bromus inermis):
    Image titled Bromus inermis
    Extensively creeping-rooted perennial. Erect hairless stems up to 1.5 m tall. Rhizome dark-coloured and jointed; internodes covered with large, scaly, brown to black sheaths, and each node produces roots and shoots. Leaf blades flat, 15 to 40 cm long, 5 to 15 cm wide, nearly hairless. Sheaths closed with small V-notch. Few hairs may be found in sheath. Ligule 1 to 2 mm long browning at base. Auricles absent. Nodding, open panicle 5 to 20 cm long with 1 to 4 branches per node often only on one side of the stem. Several spikelets per branch, each 1.5 to 3 cm long; purplish brown; 7 to 10 flowered. Awns short, less than 3 mm long.
    • Very common as a forage (hay and pasture) crop throughout North America, introduced from Eurasia as a forage crop as early as 1875. A problem weed because it often persists after cultivation and infests crops sown after.
  • Japanese Brome (Bromus japonicus):
  • Cheatgrass (Bromus tectorum): Also known as Downy Brome.
  • Large Crabgrass (Digitaria sanguinalis):
  • Barnyard Grass (Echinochloa cusgalli):
  • Foxtail Barley (Hordeum jubatum):
  • Persian Darnel (Lolium persicum):
    Image titled Lolium persicum
    Similar to and easily confused with quackgrass, except smaller, with awns, and an annual. Bright-green grass, stands 15 to 75 cm tall, roots fibrous, not creeping. Blades flat, twisted, 5 to 15 cm long and 2 to 6 mm wide; upper surface sandpapery. Sheaths hairless, round, prominently-veined overlapping margins. Auricles present when plant reaches 5-leaf stage, small, clasping. Ligule short, 1 mm long, and papery. Inflorescence a spike-like panicle, 3 to 10 cm long, composed of several stalkless spikelets set edgewise to the stem. Spikelets 5 to 7 flowered, 10 to 20 mm long. Awns present, 2 to 8 mm long.
  • Witch Grass (Panicum capillare):
  • Wild Proso Millet (Panicum miliaceum):
  • Annual Bluegrass (Poa annua):
  • Giant Foxtail (Setaria faberi):
  • Yellow Foxtail (Setaria glauca):
  • Bristly Foxtail (Setaria verticillata):
  • Green Foxtail (Setaria viridis):
  • Johnson Grass (Sorghum halapense):
  • Medusa Head (Taeniatherum capu-medusae):
  • Nutsedge (Cyperus esculentus [yellow] & Cyperus rotunda [purple]):

Part 2
Identifying Broad-leaf Weeds

  1. 1
    Understand the characteristics of broad-leaved plants. Several key features to remember when identifying these herbaceous plants: Leaves are often broad (similar length and width measurements), with veins often netted or angularly perpendicular to the main axis. Stem characteristics vary, though many are branching, erect, singular with branching to flowers, or horizontal and spreading from a crown or rosette. Plants also spread via stolons or rhizomes. Flowers are distinct because they are often colourful, however size in comparison to the rest of the plant is variable. Seeds are found in a pod or encapsulated in a fleshy fruit.
    • Interestingly, most broad-leaved weeds have their growth points at the top or tip of the plant, not at the bottom. They also have true, full stems that branch out to leaves and flowers. Stems may be erect or spreading.
    • Unlike grasses above, broad-leaved plants, otherwise known as forbs, do not fall into one single taxonomic family, but rather many families. You may recognize a few family names such as Asteraceae (family that contains daisies, thistles, dandelions and sunflowers), and Geraniaceae (well known for geraniums), just to name a couple.
    • Because most garden plants are forbs as well (few are shrubs or woody plants, mentioned below, and even fewer are ornamental grasses and sedges, mentioned above), knowing the characteristics of a weed that sets it apart from other ornamental forbs is important even in the seedling stages. As mentioned in grasses, weeds are often highly prolific and equally competitive at that time with germinating and/or newly planted garden plants, and if left unchecked can take over a entire cultivated area.
      • It's highly recommended to know the characteristics of a forb weed before they produce flowers because elimination of such weeds shouldn't wait until they are big enough to produce flowers. Although it's hard to pick weeds when they're just germinating--first putting out their cotyledons, and not yet their first leaves--it's good to know what a weed is even when it has just began to get into their second- to fourth-leaf stage so that it can be removed. Someone unfamiliar with the various species of weeds that may grow in their gardens may not know that an unknown plant that suddenly came up with their gerberas or lobelias is in fact a noxious, highly competitive weed. To the untrained eye that little green plant coming up may just be another pretty flower to accompany what was already planted.
    • All forbs and broad-leaved weeds are dicotyledons. This means that the when these plants first emerge from a seed, they send up two primary embryonic leaves or cotyledons (also called "seed leaves"), unlike the monocotyledonous grass and grass-like species above. Trees, shrubs, and other woody plants are also dicotyledons, as are all garden or cultivated forb species grown for aesthetics, food, fibre, feed, and medicine.
  2. 2
    Find or locate a weed that would likely be a forb. Using the basic identifying characteristics described in the step above, find a plant in your garden or flower bed that obviously shouldn't be growing in there and you suspect may be a broad-leaved weed of some kind.
  3. 3
    Examine the plant. Forbs have several parts observed above ground: Leaves, stems, flowers, and growth form. Below ground, most forbs will have either a tap root, or fibrous roots similar to grasses. Forbs can propagate from a large seed bank of tiny seeds deposited the year before, or from rhizomes spreading out from the parent plant creating daughter plants via asexual reproduction. For example, White Dutch Clover plants will propagate through both methods.
    • Leaves and stems: The diversity in leaf type and structure is more complex than most people think. Leaves come in a wide variety of structural differences, and it's these differences that can make it relatively easy for someone with enough experience with plant ID to correctly identify a broad-leafed plant just by looking at a single leaf, or a set of composite leaves. Structural differences between leaves of various species of forb weeds include different types of: leaf shapes, base types, types of apices (or leaf tips), types of divisions, types of leaf venation, types of leaf margins, leaf attachment, and leaf arrangement. The most common structural differences many people look for above all mentioned here are leaf shapes, leaf attachment and leaf arrangement.
      • Leaf shapes come in two primary types, simple and composite.
        • Simple leaves come in fifteen primary shapes: Linear, lanceolate, oblanceolate, oblong, elliptical, oval, ovate, obovate, spatulate, cuneate (wedge-shaped), deltoid (triangular), cordate (heart-shaped), reniform (kidney-shaped), orbicular (circular), and peltate (shield-shaped). Simple leaves are just one leaf attached to a petiole or "stem" which attaches to a branch or along the true stem of the entire plant.
        • Composite leaves come in eleven main types: Pinnately lobed, pinnately divided, palmately lobed, palmately divided, palmately much divided, odd pinnate, even pinnate, interruptedly pinnate, compound pinnate, compound pinnate, trifoliate, and digitate. Composite leaves are a set of many leaves called leaflets, or a simple leaf that is shallowly or deeply indented, as with the first five types. Pinnate is a shape reference to that of a bird's feather. Palmate is a shape reference to a human hand.
      • Leaf attachment to the stem: Leaves attach to the main stem in several manners. They can be clasping (base of the leaf almost surrounds the stem), decurrent (clasping but the leaf base extending down along the stem), ocreate (sheathing stipules [stipules being a "minor" leaf form at the junction between the stem and the petiole), perfoliate (leaf with margins entirely surrounding the stem so that the leaf appears to be joined and surrounding the stem), petiolate or petioled (has petiole or leaf stalk), and sessile (directly attached to the stem without supporting stalk).
      • Leaf arrangement: The most popular arrangement that everyone would and should know about is alternate and opposite arrangements. But there are others, including basal (arising from the base), cauline (leaves that arise from the stem above ground level), decussate (similar to opposite except leaves are on the stem in pairs with each pair at right angles to the pair above or below), rosette (dense radiating cluster at or near ground level), or whorled (parts arranged in whorls, or rather a leaf arrangement with three or more leaves coming from a single node).
    • Flowers: As diverse in structural differences as leaves, flowers of weedy forbs vary from a single, tiny bloom to a large head that contains many flowers or florets. Flower symmetry is of somewhat importance, but majority of weed flowers are noted as "regular" or, radially symmetrical (all parts are similar in size and arrangement on the receptacle [for definition of "receptacle" see below]). "Irregular" flowers are only bilaterally symmetrical. Other important things to know of flowers are floral parts, insertion of floral structures, some important perianth parts, and some perianth types. Because some books may have a lot more in-depth terminology and because there is a surprisingly wide arrange of terms for forb weeds for flowers alone, only the basics pertaining to the weeds highlighted below especially are mentioned here. For instance, there will be no coverage of flower sexuality, perianth types or forms, numbers of floral structures (there are quite a few), nor the different parts, types, arrangement, etc. of the female and male parts of the flower. However, if there are any terms missed here, they will be defined in the description of the forb weeds mentioned below.
      • Flower parts: There are some important floral parts to know before we get to the other bullets below. Flower parts include more than just petals and stamens, there are numerous other more scientific terms that may come in handy to know when trying to identify a weed. The perianth, mentioned above and below, is the collective parts of the flower, especially the calyx and corolla when they are similar in appearance. The calyx is the outer perianth whorl, or the collective term for all the sepals of a flower. A corolla is the collective name for all the petals of a flower, or the inner perianth whorl. Most people would understand that a petal is an individual segment or member of the corolla which is usually coloured or white. A sepal, on the other hand, is the segment of the calyx, and is the green "leaves" of the flower that reside underneath the petals. The pedicel is the stalk of a single flower in an inflorescence (remember inflorescence is a term referring to the flowering part of a plant, be it a flowering cluster, or the arrangement of flowers on a flowering axis). A peduncle is the stalk of a solitary flower or flower cluster arranged on an axis. The receptacle of a flower is the portion of the pedicel which the flower parts are born or, as in the flowers of Asteraceae, it's the part of the peduncle where the flowers of the head are born (a "flower" of a dandelion, for instance, is actually made up of many tiny flowers). The receptacle is also known as a torus (plural: tori). Finally, as we all know, the pistil is the female reproductive organ of the flower consisting of a stigma, a style and and ovary, and the male reproductive organs are the stamens which consist of an anther and a filament. The collective term for all female reproductive organs of a flower is called gynoecium, and androecium is a collective term for all male parts of a flower.
      • Insertion of floral structures: What's fascinating about flowers is that there are actually three different ways floral structures are attached in relation to the location of the sepals. Epigynous, is a term used to describe a flower's stamens, petals and sepals attached to the top of the ovary, with the ovary inferior (or below) to the other floral parts. Hypogynous means that the ovary is superior to other floral parts (above where the sepals are, generally), and the stamens, petals and sepals are all attached below the ovary. Perigynous is a little more tricky because it refers to the stamens, petals and sepals attached to a calyx tube (also called a hypanthium) which surrounds but is not actually attached to the superior ovary. You can only find out of a flower is of the very latter by dissecting it under a strong magnifying glass or a dissecting microscope, especially with small flowers.
      • Perianth parts: Different flowers of different species have different parts, and some parts may have more than one name. Pea flowers, for instance are made up of the banner, the ala, and the keel. The banner is the upper and largest (usually) petal of the pea-type flower, and may also be called the vexillum. The ala (pl. alae) is one or two lateral petals of the pea-type flower (also called the "wing"), and the keel is the lower two united petals of that same flower. Of a petal itself, there is the blade (broad portion) and the claw (narrowed base of some petals and sepals). In flowers of the Asteraceae family, each floral head is made up of several ray or disk flowers which have a ligule (the flattened part of the ray corolla, not quite like the ligule of grasses above), pappus (modified calyx consisting of awns, scales or bristles at the base of the "achene" [tiny seed of the dandelion, for instance]) or squama (pl. squamae; scales of some pappus types).
    • Growth forms: Not all weedy forbs are going to be up-right flowers that children often draw when they think of a plant, or even a weed! Growth forms of broad-leaved weeds do include erect, but also refer to those that grow along the ground or are creeping. Lax forms are also common.
  4. 4
    Make an identification guess on the species or common name of the plant. Most who are new to identifying plants feel most comfortable referring to the common name of a plant, and choose to learn the species' scientific, Latin or Greek taxonomic names later.
    • However please note that it's very common for a single plant to have more than one common name, depending on location and the language of those referring to a particular plant, so use of common names exclusively in identifying any plant, weed or not, is discouraged especially in the world's scientific community. This is because many plants have one taxonomic name, and that one taxonomic name is often the name that is easily recognized in all languages in by many people in all regions.

The Forb Weeds

Thus, with the list of some of the forb weeds mentioned below, both the North American common name and the world-wide accepted scientific name are used along with the brief physical descriptions of each plant.

  • Cleavers:
  • Lamb's Quarters:
  • Field Bindweed:
  • Common Burdock:
  • White Dutch Clover:
  • Dandelion:
  • Canada Thistle:
  • Common Groundsel:
  • Shepherd's Purse:
  • Burweed:
  • Chickweed:
  • Jimson's Weed:
  • Wild Tomato:
  • Scentless Chamomile:
  • Hemp Nettle:
  • Stinging Nettle:
  • White Cockle:
  • Cow Cockle:
  • Stinkweed:
  • Broad-leaved Plantain:
  • Pineappleweed:
  • Wild Buckwheat:
  • Redroot Pigweed:
  • Kochia:
  • Ground Ivy:
  • Spotted Knapweed:
  • American Dragonhead:
  • Henbit:
  • Pale Smartweed:
  • Common Peppergrass:
  • Perennial Sow Thistle:
  • Purslane':
  • Thyme-Leaved Spurge:
  • Dayflower:
  • Black Medic:
  • Common Tansy:
  • Sweet Clover:
  • Wild Buckwheat:
  • Knotweed:
  • Absinthe:
  • Leafy Spurge:

Part 3
Identifying Woody Weeds

  1. 1
    Understand the characteristics of woody plants. Woody plants share very similar attributes and growth characteristics with forbs above, and many forbs actually share the same families as woody plants. For instance, caragana mentioned below is in the same family as the clover species and black medic mentioned above, which is Fabaceae, or the Legume (Peas and Beans) Family. The only thing that sets woody plants apart from their herbaceous counterparts is that the stems are not annual (grow up from seed or root growth points every year) like forbs are. The stems also form secondary tissues, primarily xylem, on the interior of the stem, and its these xylem cells, with their very strong and rigid structures, are what make up what we know as "wood." In trees and shrubs subject to seasonal changes, rings develop in the woody tissues in response to growth patterns that occur in the spring and summer. Tropical trees, however, do not form rings because the cambrium (tissue that can grow due to cell division, and makes up xylem [inside layer] and phloem [outside layer], of a plant stem) experiences active growth all year round[6]. Flower and leaf characteristics mentioned above also apply to woody plants, exceptions are those gymnosperms, largely as coniferous plants like spruce and pine trees.
  2. 2
    Find or locate a weed that would likely be a woody plant. Using the basic identifying characteristics described in the step above, find a plant in your garden or flower bed that obviously shouldn't be growing in there and you suspect may be a woody weed of some kind.
  3. 3
    Examine the plant. Woody plants are characterized by structure of the leaves, flowers, seeds or fruit, stems, and growth form.
  4. 4
    Make an identification guess on the species or common name of the plant. Most who are new to identifying plants feel most comfortable referring to the common name of a plant, and choose to learn the species' scientific, Latin or Greek taxonomic names later.
    • However please note that it's very common for a single plant to have more than one common name, depending on location and the language of those referring to a particular plant, so use of common names exclusively in identifying any plant, weed or not, is discouraged especially in the world's scientific community. This is because many plants have one taxonomic name, and that one taxonomic name is often the name that is easily recognized in all languages in by many people in all regions.

The Woody Weeds

Thus, with the list of some woody weeds mentioned below (not all can be listed here, both of those common to North America nor those found in other parts of the world), both their common names and the world-wide accepted scientific name are used along with a very brief physical description of each plant.

  • Wild Rose:
  • Poison Ivy:
  • Morning Glory:
  • Aspen Cottonwood:
  • Poplar Cottonwood:
  • Caragana:
  • Buckbrush:
  • Japanese Knotweed:


  • Note that all plants considered as weeds are not listed here. There are thousands, possibly millions of plants in the world that may be considered weeds, and not all of them can be listed here.
    • The weeds provided are mere examples of those most commonly found in most parts of the world. If you have a plant that does not match the pictures and descriptions here, you may need to reference a weed book that is local to your area, or contact a weed specialist to identify it for you.
      • However, more weed species can be added in the steps above.
  • Note also that methods to control the weeds mentioned above are not mentioned here, primarily because control methods are often different and unique for each species. Use this article as a means to know how to identify a weed and possibly identify one that has been mentioned here.
  • Many weeds are edible, such as dandelion, purslane, bamboo, kudzu, lambs quarters, Japanese knotweed, watercress, and red clover.
    • Many weeds are also poisonous, like giant hogweed, Jimson weed, tall buttercup, leafy spurge, and tansy ragwort.


  • Alternate: A leaf of bud arrangement where there is one leaf or bud at each node.
  • Annual: A plant that lives one year or less. These plants germinates and matures to produce seed, then dies soon after.
  • Auricle:
  • Awn:
  • Basal: Base of the plant
  • Clasping: Partly surrounds the stem.
  • Collar:
  • Culm: Also known as the stem of a grass plant.
  • Fibrous Roots: A root system with many fine, diffuse roots.
  • Floret:
  • Flower Head: A cluster of individual flowers or florets in one compact unit; often in reference to compound flowering plants of the Sunflower Family (Compositae).
  • Glumes:
  • Ligule:
  • Node:
  • Opposite: A leaf of bud arrangement where leaves or buds appear in pairs at a node.
  • Palmate: Leaflets, lobes or veins that arise from the same point at the tip of the stalk, like a palm leaf.
  • Panicle:
  • Perennial: Plants that live two or more years.
  • Pinnate: Leaflets or lobes developing from different points along the main leaf axis; like a human hand.
  • Rhizomatous: Having rhizomes.
  • Rhizomes: Horizontal stems growing beneath the soil surface which can develop roots or new plants at the joints.
  • Spikelet:
  • Spike:

Things You'll Need

  • Plant Identification book (preferably local to your area)
  • Gardening gloves

Sources and Citations

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Article Info

Categories: Articles Currently In Use | Garden Pests and Weeds | Plant Identification