Scientific Family
Asteraceae
Synonyms
Anthemis foetida, Chamaemelum cotula, C. foetidum, Maruta cotula
Other common names
dog fennel
mayweed
mayweed chamomile
stinkweed
dog's chamomile
Plant type
Forbs and Subshrubs
Origin
Introduced
Lifecycle
Annual
Similar species
Anthemis arvensis
Height
4 inches to almost 2 feet
Riparian
Yes
Bushy, taprooted annual, foul odor; upright and branching green stems, sometimes red-tinged; stems topped by a single large daisy-like flower head having an outer ring of white petals (ray flower) enclosing a yellow center; thin leaves are deeply divided.
Annual weed with a rank odor; stems branched throughout or at tips; leaves finely dissected and alternate; flower heads of ray and disc flowers, solitary at the tips of the numerous and leafless branches; single-seeded fruit furrowed, gland dotted.
Habitat
Disturbed sites, roadsides, streams, ditches, fields, waste places, barnyards.
Plant Community
Riparian
Disturbed Areas
Low elevation
2500
High elevation
8000
Flower Characteristics
Flower head to 1-1/4 inches wide with an outer ring of 10 to 15 white petals enclosing a center of hundreds of tiny yellow flowers (disc florets) that form a small round center dome. Hairy modified leaves surround the base of the flower head.
Flower color
White, yellow
Flower shape
Daisy or dandelion-like
Tubular
No
First bloom month
April
Last bloom month
July
Flower clusters
None
Leaf and Stem Characteristics
Stems smooth or have a sparse covering of hairs; leaves grow to 2-1/2 inches long and 1 inch wide, are deeply divided into narrow, pointed, very thin lobes, covered with long, soft, woolly hairs and dotted with glands; can cause a skin rash if touched.
Leaf type
Compound
Leaf color
Green
Leaf shape
Pinnatifid
Leaf margin
Lobed
Leaves clasp
No
Leaf hairs
Leaves & stems
Spines
No
Fruit and Seed Characteristics
Fruit is 1/16 inch, dry and single-seeded with a bumpy surface. Its shape is narrowly cylindric with 10 grooved, gland-dotted, lengthwise ribs; doesn't split to release seeds when ripe and lacks tufts of hair at its top to aid seed dipersal by wind.
Fruit type
Achene
Fruit color
Light yellow to brown
Seeds have a smooth surface and are dispersed by wind shaking the stem and by water as they are light enough to float easily. Each plant can produce thousands of seeds (up to 960,000 on large plants) which remain viable in the soil for several years.