PL SC 352 Lab 6

Pineappleweed

Matriciaria discoidea

Annual

Oblong, stalkless cotyledons

First true leaves long, narrow with lobed margins, they appear to have 2 basal lobes

Finely divided leaves (dill-like/feathery)

Erect, short stature, smooth stems, much-branched

Very similar to scentless chamomile

Crushed fruits smell like citrus/pineapple (kinda)

Conical to ovate heads with tiny, yellow-green disk florets only

Each flower produces one olive-brown achene with 3-5 ribs. No pappus

General distribution. Found in waste places. Grows on compacted soil.

Scentless Chamomile

Tripleurospermum inodorum

Life cycle: Annual, winter annual, biennial, simple perennial

Oval, egg-shaped, sessile cotyledons

1st leaves smooth, deeply divided often into 5 segments

Finely-divided leaves (dill-like/feathery), no odour

Fibrous root system

Erect, smooth, much-branched stems

Other names: Scentless Mayweed, Barnyard Daisy

Daisy-like heads singly at the ends of branches

Yellow disk florets, white ray florets

When ripe, ray florets tend to point backwards

Disk florets produce 1 dark brown seed (achene) with 3 ribs and no pappus. Very prolific seed producer (~1 million/plant)

Noxious in AB. Waste areas

Oxeye daisy

Leucantheumum vulgare

Life cycle: Creeping perennial

Oval, stalkless cotyledons

1st true leaves broadly oval (spoon-shaped) with wavy margins

Clustered basal leaves, leaves petioled, spoon-shaped with irregular margins, dark green with smooth surface

Tall stems emerge from a thick crown. Upper leaves narrow, deeply toothed, sessile and/or clasping

Strong, unpleasant odour

Short, shallow creeping roots

Yellow disk and white ray (female) florets in heads

Each disk floret produces a single narrow, black seed (achene) with 10 white ribs and no pappus

Overlapping rows of green bracts with brown margins

Central, E AB. Escaped ornamental.

Noxious

Groundsel

Senecio vulgaris

Life cycle: Annual, winter annual

Cotyledons oblong with a grooved stalk

1st true leaves oval with apical-pointing teeth

Rosette leaves pinnately lobed with toothed margins, alternate, fleshy, prominent midrib underneath

Short, erect, hollow stems

Upper leaves sessile, irregularly lobed with toothed margins

Small, cylindrical heads, not very showy. Yellow disk florets surrounded by black-tipped involucral bracts (usually)

Narrow, tan-coloured seeds with white pappus

Up to 4 generations/season; prolific seed producer

Senecionine - toxin causing liver damage in livestock

Tansy

Tanacetum vulagare

Creeping perennial

Ovate cotyledons; 1st leaves petioled, hairy with slightly lobed-toothed margins

Leaves are progressively more lobed and hairless as you ascend the stem

Basal leaves alternate, nearly pinnately divided, with evenly subdivided margins.

Stem leaves sessile, pinnate, smaller than basal leaves

Leaves covered with glands making the whole (rosemary/basil/camphor-like)

Somewhat poisonous to livestock

Short rhizomes; forms clumps; erect, smooth stems

Clusters of corymbs (flat-top) - dense, round heads with short yellow disk florets (button- shaped)

Each floret produces a long, yellow-brown seed with longitudinal ribs. Pappus reduced to a short, 5-lobed crown

Noxious

Orange Hawkweed

Pilosella aurantiaca

Stiff hairs (often dark/black) on stems, leaves, involucre.

Orange (reddish/yellowish) capitulum.

Basal rosette.

Milky latex.

Dandelion-like cluster of wind- dispersed seeds.

Generally taller than dandelion.

Leaf margins smooth, notirregular/jagged (like in dandelion).

Annual Sow Thistle

Sonchus oleraceus

Life cycle: Annual, winter annual

Seedling appears same as other sow thistles.

Smooth, oval cots.

Leaves not glossy, deeply lobed to divided margins; weak, sparse, soft prickles, usually triangular terminal lobe

Milky latex, often purpling in stem and petioles.

Lower leaves stalked; upper clasping leaves have basal, pointed lobes

Often broad triangular terminal leaf lobe on leaves (not always, but useful in perennial/field sow thistle vs. annual ID)

Triangle-ish head flower, dandelion-like yellow ray florets

Short taproot, thrives in disturbed areas, especially where there is over-grazing

Spiny Sow Thistle

Sonchus asper

Life cycle: annual

Glossy, clasping, lanceolate leaves

Rounded auricles

Sharp prickles (painful)

Triangle-ish head flower, dandelion- like yellow ray florets

Milky latex

Common Dandelion

Taraxacum officinale

Life cycle: perennial

Smooth, oval cots.

1st leaves oval with sparse, irregularly toothed margins

Deep tap root

Leaves are in a basal rosette throughout the lifecycle

Leaves irregularly lobed and toothed (no prickles)

Whole plant has milky latex

Solitary flower heads on hollow leafless stalks (scape)

Bright yellow ray florets, two involucres subtending the head

The achene is yellow-brown with a long, slender beak and pappus.

Introduced. Common in lawns, in perennial forage crops; becoming a problem in reduced tillage systems

Red-Seeded Dandelion

Taraxacum erythrospermum

Easily mistaken for common dandelion

Has reddish seeds

Has consistently triangular leaf lobes, rather than variously irregular

Goat’s Beard

Tragopogon dubius

Life cycle: biennial

Cotyledons long and linear

Seedling leaves sessile, entire.

Deep, thick tap root; stems smooth, hollow, milky sap

Young leaves covered in soft, downy hairs; older leaves appear grass-like, but are smooth/fleshy and clasping

Very large, flat-topped head; stems below head are thickened.

Yellow ray florets enclosed by 1 ring of long, narrow involucral bracts.

Large, white fluffy heads (large seeds with pappus)

Narrow ribbed seed with long beak, feathery pappus

Russian Knapweed

Leuzea repens

Life cycle: Creeping perennial

Scaly brown creeping roots.

True leaves densely hairy giving a gray-green appearance with irregularly lobed margins

Erect, much-branched. Lower leaves alternate, sessile to clasping. Upper leaves small, usually entire/linear with a soft spine at the apex

Disk florets only, spherical heads; magenta-purple

Each head surrounded by a whorl of scale-like involucral bracts; green at the base with white/clear papery margins and smooth tips

Pappus of stiff white hairs

Likes poorly drained alkaline/saline soils

Noxious weed in AB. Allelopathic

Canada thistle

Cirsium arvense

Life cycle: Creeping perennial

Extensive, deep creeping root system; survives cultivation

Stems erect and hollow

Basal rosette, upper leaves alternate, sessile, lanceolate, shiny, irregularly-lobed, violent prickly margins

Numerous heads in terminal and axillary clusters with magenta-purple disk florets (rarely white). Dioecious. Male heads have smaller/less showy ray florets, female are “poofy”.

Spiny green+purple involucral bracts with sharp tips/hooks

Female flowers produce one tan coloured, curved seed with a feathery pappus. Poor germination

Introduced. Host plant for the ‘Painted Lady’ butterflyIn some opinion, the worst weed in Canada.

Allelopathic

Can extensively reproduce from root fragments, plus high seed production (& airborne).

Resistant to herbivory (sharp leaves, sharp bracts).

Biocontrol: Puccinia punctiformis (rust fungus)

Canada Thistle vs Russian Knapweed

Canada Thistle

• Bracts green-purple, pointed/hooked tips

• Upper leaves lanceolate/lobed/prickly

Russian Knapweed

• Bracts green-white

• Upper leaves small/linear/entire