Weed - Seedling Identification Guide

Reprinted February 2008 Contents

Species Page Absinth ...... 9 Night-flowering catchfly ...... 16 American dragonhead ...... 23 Nodding thistle ...... 19 Barnyard grass ...... 3 Persian darnel ...... 3 Biennial wormwood ...... 25 Pineappleweed ...... 10 Bladder campion ...... 13 Proso millet ...... 4 Bluebur ...... 19 Prostrate knotweed ...... 12 Burdock ...... 13 Prostrate pigweed ...... 12 Canada thistle ...... 14 Redroot pigweed ...... 13 Chickweed ...... 9 Round-leaved mallow ...... 23 Cleavers ...... 14 Russian pigweed ...... 17 Cocklebur ...... 9 Russian thistle ...... 8 Common groundsel ...... 10 Scentless chamomile ...... 10 Common peppergrass ...... 11 Shepherd's-purse ...... 20 Corn spurry ...... 8 Smartweed and lady's thumb .... 17 Cow cockle ...... 14 Sow thistle ...... 20 Curled dock ...... 15 Stinkweed ...... 20 Dandelion ...... 15 Stork's-bill ...... 24 Diffuse knapweed ...... 15 Tartary buckwheat ...... 24 Dog mustard ...... 21 Thyme-leaved spurge ...... 17 False ragweed ...... 21 Viper's bugloss...... 21 Field bindweed ...... 22 White cockle ...... 18 Flixweed ...... 11 Wild buckwheat ...... 18 Giant ragweed ...... 19 Wild cranesbill ...... 23 Green foxtail...... 3 Wild cucumber ...... 25 Hemp nettle ...... 24 Wild mustard ...... 22 Kochia ...... 11 Wild oat...... 4 Lambs' quarters ...... 12 Wild tomato ...... 8 Milkweed ...... 16 Yellow toadflax ...... 22 Narrow-leaved hawks' beard .... 16 Yellow whitlow grass ...... 18 Glossary

Alternate leaves - single leaves attached at different positions on the stem, not opposite each other. Auricle - earlike appendage which wraps around the stem of some grass plants at the junction of the leaf blade and the stem . Basal leaves - leaves attached to the base of the plant. Biennial - a plant which takes more than one growing season, but not more than two years, to complete its life cycle. Blade - the expanded, usually flat, part of a leaf. Bloom - a whitish, powdery covering. Cotyledons - the first leaf or pair of leaves originating from the seed (seed leaves). Glossy - having a shiny surface. Keel ~ prominent ridge on the back of a leaf sheath or blade usually along the midrib. Ligule - flap of membranous tissue or fringe of hairs on the inside of a grass leaf where the blade joins the stem. Mid-vein - (midrib) - the central vein or rib of a leaf. Node - joint in the stem where leaves or branches are attached. Opposite leaves - two leaves originating from the same point on the stem and opposite each other. Petiole - the stem of a leaf. Rosette - a flat, circular cluster of leaves formed at the ground surface. Usually an overwintering stage. Sheath - the lower part of a leaf that surrounds the stem or shoot. True leaves - leaves that develop after the cotyledons. Whorl - three or more leaves attached at the stem at the same point (whorled). Seedling Grass Identification I Vegetative Parts of a Grass Plant Barnyard grass Echinochloa crusgalli

4 • no auricles I • no ligule f- e1ade • leaf hairless or 1-3 solitary hairs at base of blade

Collar

Sheath ~' Green foxtail t Setaria viridis

• no keel Types of Ligules • leaf margins and surface WILD OATS GREEN FOXTAIL BARNYARD GRASS rough with fine upward pointing barbs • ligule a fringe of hair 1 .5-2.0 mm long • no auricles

MEMBRANOUS FRINGED WITH LEAF WITHOUT LIGULES HAIRS A LIGULE

Shapes of auricles and (right) a collar without auricles.

Persian darnel Lolium persicum

• shiny dark green on upper leaf surface • base of stem is reddish­ purple • membranous ligule to 1 mm long CLAWLIKE ROUNDED RUDIMENTARY COLLAR • auricles usually present WITHOUT AURICLES

2 3 Broadleaf Weed Identification Seedling, Cotyledons generally reach Proso millet their full size and shape by the Panicum miliaceum Broadleaf Weed time the first true leaf is visible between them. Prior to this stage accurate identification of • leaf blade and sheath the seedling is difficult. covered with dense stiff hairs • ligule a fringe of hairs fused at the base, 3.0-4.0 mm long

Wild oats To use table: Avena fatua a) Compare cotyledon shape with shape in left hand column. • Counter-clockwise leaf twist b) When similar shape is located turn to pages indicated and compare true • no auricles leaves in photos with weed specimen for identification. • hairs on leaf margins NOTE: Weed species are arranged according to cotyledon shape. • membranous ligule Cotyledon Shape Weed Page

• Corn spurry 8 usually less than 1 mm broad, a • Russian thistle few mm in length, almost of 8 uniform breadth throughout. I • Wild tomato 8 at least 10 times as long as broad, • Cocklebur top tapering to a point, more or 9 less long stalked, tapered gradually into the stalk, usually broader in the middle than at the t ends.

• Chickweed narrow-oval to ovate, top tapering 9 to a point, base rounded or • tapering into the stalk. • Absinth 9 with broad base, or slightly narrowed at base, at most 2-3 • Pineappleweed times as long as broad, compact, 10 I occasionally fleshy. • Scentless chamomile 10

4 5 Cotyledon Cotyledon Shape Weed Page Shape Weed Page

• Common groundsel 10 • Dog mustard 21 top flat with slight indentation, • Common peppergrass 11 base gradually tapering into the • Flixweed 11 • False ragweed stalk, broadest above the middle. 21 • Kochia elongated, elliptical, with a more or less long stalk. 11 • Lamb's quarters 12

• Prostrate knotweed 12 • Field bindweed top deeply indented, base 22 • Prostrate pigweed 12 ' gradually narrowed into stalk. ' • Redroot pigweed 13 9 • Wild mustard 22 • Bladder campion 13 • Burdock 13 top rounded, sides incurved, • Canada thistle 14 • Yellow toadflax gradually tapered into stalk at the 22 base. • Cleavers a very variable group, oblong to 14 • Cow cockle broadly oval , rounded at the base 14 • or narrowing to a more or less • Curled dock long stalk. All have a compact 15 • Dandelion form with rounded top. 15 • Round-leaved mallow traingular shape, top rounded. 23 • Diffuse knapweed 15 • Milkweed 16 • Narrow-leaved hawk's beard 16 • Wild cranesbill broader than long. 23 • Night-flowering catchfly 16 • Russian pigwed 17 ' • Smartweeds 17 • Thyme-leaved spurge 17 • American dragonhead 23 • White cockle 18 outline of the cotyledons • Hempnettle orbicular-oval , the base has a 24 • Wild buckwheat 18 pointed auricle on either side of • Yellow whitlow grass 18 the stalk, or is rounded. tJ • Tartary buckwheat 24 • Bluebur 19 • Giant ragweed 19 three-lobed or deeply divided into usually markedly stalked (stalk • Stork's-bill 24 three. • Nodding thistle occasionally very short), gradually 19 • Shepherd's purse tapering or rounded at the base, 20 4- generally broadest at or above the • Sow thistle middle. 20 • Stinkweed 20 " • Viper's bugloss 21 • Biennial wormwood indented at top. 25 ~ • Wild cucumber with a broad base very large and 25 ' fleshy.

6 - 7 ., .,....,,,,

Corn spurry Spergula arvensis Cocklebur Xanthium spp. • leaves similar to Russian thistle but occur in whorls • coarse-veined true leaves \\ 1 on the stem • first two leaves paired, later t I • leaves may be slightly leaves alternate ' _µ . sticky and have blunt tips •

Chickweed Russian thistle Stellaria media Sa/so/a pestifer • cotyledons slightly • long, fleshy, needle-like constricted at tip leaves and cotyledons • conspicuous line of hairs I • leaves have sharp tips on one side of stem later in t development

Absinth Wild tomato Artemisia absinthium Solanum triflorum nutt. • leaves silvery, hairy on both • leaves deeply lobed with I surfaces scattered hairs I • characteristic odor

8 9 Pineappleweed Matricaria matricarioides Common peppergrass Lepidium densiflorum • extensively divided leaves, resembles a coarse carrot • granular bloom on leaves I top • base of leaf stalk downy, • leaves have strong whitish appearance pineapple odor when \ • forms rosette crushed ' .,

' ., ~, -> ,:-,.:!~--··-... Flixweed f. . ' . . . ' .. . . . ,. ~ Scentless chamomile Descurainia sophia . : .., .. : .,,_ -~ ' •.f. . -•, ill .•t\ ~- =· Matricaria maritima . : ~ . • first two true leaves are 3 .. ,...... 'l . lobed ~ 2:1:.;:~. ,::~/~ ~\i:~ • • similar to pineappleweed .•·•~.:_a ,:'• ~~ ,_. • leaves have no odor when • other leaves finely divided, I ~-~ crushed grey-green 111.'1 ~~:. • covered with fine hairs ~,·. <(' ·.·•··. 4/; • more finely divided than -·N·.,•. • leaves alternate except for >· pineappleweed .... ., ....+· -,_._ • . .•••:e ~· first two :·~·t: tt -.f ~~~\. . •;( .·-~ :~ . --~l: .• . ... ' -°.: ... - ' . . - • odorless •. *!-~" Iii/ii ' ~- . li' . ,-·

Common groundsel Senecio vulgaris Kochia • cotyledons and leaf stalks Kochia scoparia deeply grooved at base • cotyledons bright pink • leaves alternate, prominent underneath keeled mid-vein • leaves covered with soft, underneath fine hairs • forms rosette in early • no odor ' stages '

10 11 Redroot pigweed Lamb's quarters Amaranthus retroflexus Chenopodium album • underside of cotyledons • underside of cotyledons and base of stem dark red and young leaves pinkish • first true leaves prominently • young plant covered with veined, as long as broad silvery particles, especially • mid-vein of first true leaves conspicuous on underside extends as a small of leaves t· temporary bristle in the notched tip ' ,I '

Prostrate knotweed Polygonum aviculare Bladder campion Silene cucubalus • cotyledons long and narrow • hairless • papery sheath at base of • cotyledons slightly petioled leaf • true leaves in pairs, united • common on hard packed at base ' areas '

Burdock Prostrate pigweed I Arctium minus Amaranthus blitoides • waxy surface on cotyledons • cotyledons longer than ,\ • true leaves petioled redroot pigweed • true leaves coarse-veined • first true leaves longer than and downy on undersurface they are broad • leaf stalk flared and clasping at base to form a ' tubular sheath '

12 13 Curled dock Rumex crispus Canada thistle Cirsium arvense (L) scop. • large distinct true leaves with veins prominent • leaves ovate to lanceolate, beneath margin with numerous • papery sheath at base of triangular indentations and leaf sharp spines • emerging leaf has sides ' tightly rolled under '

Cleavers ~- ,- 1~-- .. ~,, ,, ... ~- ~. ~z.. • ' ,,, , {'j - Ga/ium aparine Dandelion ' . , ')I: I Taraxacum officinale ~. •""#J ·' Vii .. ~~ -.. ~}' ,. • square stem with stiff, ,....,.~~t. ·l!\'r,.tl, 'l. .. ~ •1•! * downward pointing hairs • cotyledons not fleshy, ., •; ,,_,.,, (clings to clothing) margins vary ~-- ," ii/-i. ' • true leaves in whorls of 4 • milk sap '

Cow cockle Saponaria vaccaria Diffuse knapweed Centaurea diffusa lam. • leaves hairless, long, narrow, fleshy, keeled ? • leaves alternate, divided mid-vein into narrow segments, with • leaves opposite, united at short stiff hairs ' base '

14 15 Milkweed Asclepias spp.

• milky juice • cotyledons have few Russian pigweed granules above, shiny Axyris amaranthoides beneath • true leaves in pairs, • first true leaves tapered prominent mid-vein toward both ends, beneath, short hairs on prominent mid-vein margin • leaves enlarge greatly as ' plant ages '

Smartweeds and Lady's Narrow-leaved thumb hawk's-beard Polygonum spp. Crepis tectorum • cotyledons attached at • leaves not hairy 180° from each other when • distinct barbs on margin of viewed from above true leaves • papery sheath circles the ' stem at base of leaf petiole '

Thyme-leaved spurge Euphorbia serpyllifolia Night-flowering catchfly Silene noctiflora • cotyledons and leaves pinkish underneath • leaves in pairs, spoon­ shaped, widen towards end • true leaves have indented before tapering to a point, edges around top of leaf, hairs on margins pinkish line in middle of leaf • plants have white, milky ' sap '

16 17 White cockle Bluebur Lapputa echinata Lychnis alba

• cotyledons often somewhat • covered with stiff hairs • mousy smell constricted at the tip • hairs on margins of true • distinct central crease in true leaves ' leaves "

Wild buckwheat Polygonum convotvutus Giant ragweed • cotyledons attached at Ambrosia trifida 120° to each other when viewed from above • leaves and stem rough to • papery sheath at base of touch leaf petiole • true leaves after first pair • true leaves arrowhead are distinctly 3-lobed shaped, longer than they ' are broad "

Nodding thistle Carduus nutans

Yellow whitlow grass • cotyledons have broad Draba nemorosa L. white veins • cotyledons very small • margins of true leaves prickly • forms rosette • flowering quite early in the • veins prominent on spring undersurface of true leaves • rosette first year (biennial), ' silver-grey color "

18 19 ..

.. Viper's bugloss ,,.,a_·,·1···.•···•·· .. Shepherd's-purse Capsella bursa-pastoris Echium vulgare f··,. • forms a rosette • covered with short, stiff hairs • upper surface of true ·~. leaves slightly hairy • rosette first year (biennial) ..,};~,· • upper surface of leaf is • basal leaves narrow into a d rough or worty . . stalk ' . . , " " , '·H· • . • '

Sow thistle Dog mustard Erucastrum gal/icum Sonchus spp.

• cotyledons fleshy • cotyledons less notched • milky sap than wild mustard " • soft prickles on later leaves • germinates late '

Stinkweed Th/aspi arvense False ragweed • hairless plant Iva xanthifolia • true leaves can be variable in shape, prominent and • hairs on margins of shiny veins beneath cotyledons • distinct odor especially • true leaves opposite when bruised • fine whitish-hairs on leaf . ' • often grows in rosette form blades ' " .. •

20 21 Field bindweed Round-leaved mallow Convolvulus arvensis Malva pusilla = M. rotundifolia

• no papery sheath at base of • distinct cotyledons appear stem as in the buckwheat prominently veined with family glossy surface • prominent veins on • leaves crinkly, indented undersurface of true leaves margins, cup-shaped, long stalks

Wild cranesbill (Bicknell's geranium) Wild mustard Geranium bicknellii Sinapis arvensis • cotyledons covered with • hairs on leaf and stem granular bloom above, • leaf shape is variable veins are depressed • indented cotyledon tip • scattered, short hairs on leaves and leaf stalks

\

Yellow toadflax American dragonhead Linaria vulgaris Dracocephalum parviflorum

• cotyledons have a • cotyledons rounded with distinctive bump near tip backward pointing • first true leaves smooth and projections egg-shaped, later leaves • lower 213 of first true leaves longer and more slender e1 • round-toothed • no milky juice • forms a rosette (biennial)

22 23 Biennial wormwood Hemp nettle Artemisia biennis Galeopsis tetrahit • cotyledons united at base • cotyledons distinctly to form a small fleshy cup notched • leaves grey-green and • true leaves are opposite mealy, ridged veins on e1 and hairy upper surface • square stem • wormwood or sage scented when bruised 1 '

Tartary buckwheat Fagopyrum tataricum Wild cucumber Echinocystis lobata • cotyledons broad and notched • cotyledons thick green, a • papery sheath at base of few veins evident e1 leaf • leaves pale green rough on • triangular leaves, as broad both sides as long

Stork's-bill Erodium cicutarium

• three-lobed cotyledons • • finely divided true leaves

24 25 ~~ COVERING NEW GROUND Manitoba Agricultural Sustainability Initiative

Reprinted February 2008. Printed in Canada MG 6907 Agdex 640