Horticulture Crop Weeds

CS 414 Weed Science Laboratory

Hairy galinsoga

Galinsoga ciliata

Asteraceae

Summer annual, upright, branching

Pubescent stems & leaves (upper surface of blades)

Opposite leaves with toothed margins

White flowers – both disk and ray flowers (toothed) present

Common purslane

Portulaca oleracea

Asteraceae

Summer annual, prostrate

Rounded leaf apex

Fleshy leaf blade

Yellow flowers in leaf axils open in sun

Similar in appearance to P. pilosa – note flower color, apex, and leaf shape

Common Name: pink purslaneFamily: Asteraceae Genus: Portulaca Species: pilosa  Summer annual

•leaves are thick and fleshy, arranged alternately on the stem, and have a prostrate growth habit – pointed apex

Annual sedge

Cyperus compressus

Cyperaceae

Summer annual

Many stems develop in a dense clump

Leaf blades narrow compared to PNS or YNS

Flower spikelets flattened

NO tubers or rhizomes

Cyperus esculentus

Cyperaceae

Yellow nutsedge

Perennial

Tubers are smooth and singular, yellow seed head, lance-shaped leaf

Cyperus rotundus

Purple nutsedge

Cyperaceae

Perennial

Leaf abruptly tapers to a point, broader than YNS

Tubers string together along rhizome

Virginia copperleaf

Acalypha virginica

Euphorbiaceae

Erect, branching summer annual

Rounded cotyledons have notched apex, glabrous

First true leaves opposite, later leaves alternate, lanceolate

Flowers green, in clusters yield a 3-lobed seed pod

Common Name: carpetweedFamily: Molluginaceae Genus: MollugoSpecies: verticillatasummer annual

•Carpetweed has whorls of leaves at each stem node in addition to the circular, light green, mat-like growth

Common Name: large crabgrassFamily: PoaceaeGenus: DigitariaSpecies: sanguinalisSummer annual

•densely hairy leaf and sheath•roots at the stem nodes, smooth crabgrass does not•large, jagged membranous ligule

                                             

Common Name: goosegrassFamily: PoaceaeGenus: EleusineSpecies: indicaSummer annual

•Flattened stems with a white center•ligule fringed, uneven, and membranous•Leaves folded in the bud

Datura stramonium

Jimsonweed

Solanaceae

Summer annual

Distinct midvein in cotyledons

Bur-like fruit contains many seeds

Large white flowers

Leaves with lobed margins

Stems become “woody” with age

All parts extremely poisonous

Eastern black nightshade

Solanum ptycanthum

Solanaceae

Erect summer annual

Taproot with lateral branches

Hypocotyls covered w/small hairs

Cotyledons green on upper portion of blade, purple to maroon on lower surface

Star shaped flowers yield small, green, many-seeded berries

Extremely poisonous, ripe berries may be less (not) poisonous