1. Extension Weeds and IPM Specialist
Plant Identification
Melissa Graves
Extension Weeds and IPM Specialist

2. Outline Basic plant parts Characteristics used for plant ID
Plants currently listed on the “high priority list”

3. Basic plant parts
roots
stems
internode
node
leaves
flower/fruit

4. Identifying Characteristics
Leaves
Arrangement
Parts
Types
Shapes
Margins

5. Identifying Characteristics
Flowers
Symmetry
Shape
Location
Fruit types
Root systems

6. Leaf arrangement

7. Opposite
Alternate
Whorled

8. Leaf Parts

9. Leaf type

10. Simple leaf Compound leaf Simple leaf – purple loosestrife
Compound leaf – Eurasian watermilfoil (note paired linear leaflets)

11. Leaf shape

12. Elliptic leaf Linear leaf Cordate leaf
Purple loosestrife – linear leaf
Dyer’s woad – elliptic leaf
Knotweed – cordate leaf
Linear leaf
Cordate leaf

13. Leaf margin

14. Entire margin Lobed margin Dentate margin Sinuate margin
Purple loosestrife – entire margin
Rush skeletonweed - dentate margin
Spotted knapweed – lobed margin
Curlyleaf pondweed – sinuate margin
Dentate margin
Sinuate margin

15. Flower Symmetry

16. Bilateral Symmetry Radial Symmetry
Actinomorphic (radial) flower. Imagine drawing multiple lines through the flower

17. Flower Shapes

18. Cruciform
Ligulate
Cruciform flower
Papilionaceous
(Pea flower)

19. Inflorescence Types

20. Corymb Umbel Dyer’s woad – corymb Oxeye daisy - head
Purple loosestrife – raceme
Flowering rush – umbel
Blueweed – helcoid cyme

21. Head (capitulum) Raceme Helicoid cyme Dyer’s woad – corymb
Oxeye daisy - head
Purple loosestrife – raceme
Flowering rush – umbel
Blueweed – helcoid cyme
Helicoid cyme

22. Fruit Types

23. Achene Silicle Nutlet Silicles – dyer’s woad
Achene – curlyleaf pondweed
Nutlets - houndstongue

24. Root Systems

25. Outline Basic plant parts Characteristics used for plant ID
Plants currently listed on the “high priority list”

26. Curlyleaf Pondweed Aquatic plant, leaves submersed
Leaves narrowly oblong, curly margined
Leaves clasping to stem
Forms dense mats

27. Similar Species
There are several additional pondweed species found in Montana. Most however are listed as T&E by the USDA. If you feel you could have a pondweed, please send a sample to the Schutter Lab to verify species.
Bottom – Alpine pondweed
Middle – Illinois pondweed
Top – Longleaf pondweed

28. Dyer’s Woad Bluish-green leaves with white mid-vein
Flat-topped to umbrella-shaped clusters of yellow flowers
1-4 ft. tall
Purplish brown to black teardrop-shaped seeds
Photos by Steve Dewey, Utah State University, Bugwood.org

29. Similar Species Tumblemustard Unbranched lower stem, bushy upper stem
Lower leaves broad and
divided almost to mid-vein
Upper leaves with narrow,
linear lobes
Flowers white to pale
yellow
Oregon State University uspest.org
Missouri Flora
Michael L. Charters

30. Similar Species Western Wallflower (Native) Basal leaves spreading,
linear-elliptical shaped
Leaf margins toothed (dentate)
Leaf surface with fine
hairs
Flowers bright yellow to
yellow-orange
Inflorescence tight, terminal
raceme
National Park Service
National Park Service

31. Similar Species Yellow Alyssum Stems branching at base,
3-10 inches in height
Short, narrow leaves
Stems and leaves covered
with fine hairs
Flowers white to pale
yellow
Inflorescence tight, terminal
raceme
Matt Lavin gemini.oscs.montana.edu
Mark Turner
Wikipedia

32. Eurasian Watermilfoil
Aquatic perennial
4 whorled leaves at each stem joint
>14 paired leaflets/leaf give “feathery” appearance
Foliage does not collapse when removed from water
Inconspicuous pink flowering spike above water surface
Stem width twice as wide below flower spike

33. Native Watermilfoils Distinguishing from Eurasian
Stem width remains constant below flowering spike
Sparse branching near water surface
Short-spike
<14 paired leaflets/leaf
Whorl-leaf (western)
Bracts longer than flowers
Drawings by Hilary Parkinson, MSU

34. Flowering Rush Aquatic perennial
Creeping rhizomes and bulblets (not in PNW)
Erect or floating leaves, 3 ft. long and ½ inch wide
Triangular cross-section
Umbrella-shaped clusters of pink to white flowers with 3 petals
Photos by Leslie Mehrhoff, Univ. of CT, Bugwood.org

35. Knotweed Complex Japanese, Giant, Himalayan
Separated by leaf shape and size
Hollow, smooth, jointed stems
Base of stem surrounded by membranous sheath
Up to 20 ft. tall (depending on species)
Small greenish-white flowers in sprays
Photo by Leslie Mehrhoff, Univ. of CT, Bugwood.org

36. Purple Loosestrife Height often 6-8 feet Leaves smooth margined;
either opposite or whorled on stem
Flowers rose-purple with
5-7 petals
Inflorescence is a long terminal raceme
Typically found in moist or
marshy sites
Elizabeth J. Czarapata dnr.wi.gov
Elizabeth J. Czarapata dnr.wi.gov
Kentucky Division of Forestry

37. Similar Species Fireweed (Native) Up to 9 feet tall
Leaves lance-shaped,
up to 8 inches long
Flowers rose to purple
(4 petals); inflorescence
a long terminal raceme
Flowers have linear
bracts
Matt Lavin
gemini.oscs.montana.edu
University of Northern British Columbia
web.unbc.ca
J.K. Lindsey
Walter Siegmund en.wikipedia.org

38. Rush Skeletonweed “dandelion from hell”
Sharp, deeply toothed rosette leaves
Yellow flower
Downward bent, coarse hairs on lower stem
Utah St. University, Bugwood.org
Gary Piper, Washington State Univ., Bugwood.org
Gary Old, Bugwood.org

39. Similar Species Skeletonweed Up to 18 inches tall Stems lacking hairs
Leaves small, linear, upper leaves reduced to awl-like projections
Flowers light purple
Basal leaves absent
Brian Peterson
Jim Pisarowicz
National Park Service

40. Scotch Broom Woody shrub, up to 10 ft tall Bright yellow pea flowers
Inflorescences terminal and axillary
Trifoliate leaves, entire leaflets
Seed pods only hairy on the margins

41. Similar Species Striated Broom
Currently found in California and Oregon
Bright yellow pea flowers
Terminal inflorescence
Trifoliate leaves, entire leaflets
Seed pods very hairy
Also called Portuguese broom.

42. Similar Species Whitespanish Broom
Currently found in California, Oregon, and Washington
White pea flowers
Trifoliate leaves, entire leaflets
Seed pods very hairy

43. Similar Species Yellow Sweetclover Annual to short-lived perennial
Found throughout the United States
Yellow pea flowers
Trifoliate leaves, entire leaflets
Seed pods small
Photo by Steve Dewey, Utah State University
Photo by Mary Ellen Harte (bugwood.org)
Photo by Steve Dewey,
Utah State University

44. Yellow Starthistle Annual Single yellow flower per branch
¾ -1 inch spines radiating from flower bracts
Grayish-green foliage
Vertical leaves along stem give stem a winged appearance
Photos by Steve Dewey, Utah State University, Bugwood.org

45. Similar Species Spotted Knapweed Basal leaves long, very dissected
Upper leaves narrow
Foliage gray-green, hairy
Flowers normally purple, may also be white or cream
Stiff bracts with hairy
margins and dark tips
Joseph M. DiTomaso
U.S. Fish & Wildlife
Washington State Noxious Weed Control Board

46. Similar Species Diffuse Knapweed Stems rough, 1-2 feet tall
Most leaves pinnately
divided
Flower heads narrow,
may be white to purple
Margins of bracts
comb-like
Montana Department of Ag
agr.mt.gov
Montana Weed Control Association
Salt Lake County Weed Control

47. Hydrilla Leaves in whorls of 3-6
Leaves strap shaped, minutely saw-toothed (serrate) margins
Tiny white flowers, rarely seen
Reproduces by stem fragmentation and tubers
Not currently found in Montana

48. Quiz Time A B
Which plant is purple loosestrife?

49. Which plant is dyer’s woad?B C

50. Which plant is Eurasian Watermilfoil?B

51. Additional Resources
Bugwood Network (
High Plains IPM (
Montana Extension (
Montana Weed Control Association (MWCA website )
Schutter Diagnostic Lab (
USDA Plants Database (
Weeds of the West. Whitson, T.D. et al

52. Questions? For more information contact: Melissa Graves
Extension Weeds and IPM Specialist
(406) ;