How to Manage Pests

Identification: Weed Photo Gallery

Dandelion

Scientific name: Taraxacum officinale (Sunflower Family: Asteraceae)

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Dandelion is a widely distributed perennial broadleaf weed found throughout California, except in deserts, to about 11000 feet  (3300 m). It consists of a complex of biotypes that vary with environmental conditions and is a common weed of mountain meadows and turf, especially in southern California. It also inhabits perennial crop fields, especially those in alfalfa, disturbed sites, and nurseries. It is a host of aster yellow disease, which affects a number of vegetable crops. Because dandelion contains high amounts of certain minerals, it serves as a complement to pasture forage for livestock. In addition to being weedy, the fine hairs of the one-seeded fruit can clog cultivation equipment.

Habitat

Perennial crop fields (especially alfalfa), orchards, vineyards, turf, nursery crops, pastures, and roadsides.

Seedling

Cotyledons (seed leaves) are oval, hairless, and have a midvein that terminates with a gland at the leaf tip. The first and next few leaves are football shaped to oblong, taper at the base, and have weakly toothed edges. Later leaves are widest near the tip with gradually tapering bases and sparsely-toothed edges. Young leaves form a basal rosette.

Mature plant

Dandelions have no visible stem. Leaves are sparsely hairy or hairless, with deeply serrated edges, and cluster into a rosette at the base of the plant. A strong, deep taproot exudes a milky substance when cut.

Flower

Dandelions flower nearly year-round in mild climates. The bright yellow flower head is 4/5 to 1-2/5 inches (2–3.5 cm) across and is found singly on the tip of a hollow, leafless stalk that is 3 to 12 inches (7.5–30 cm) tall. The flower head consists of many, small, yellow, petal-like flowers (ray flowers).

Fruit

A tiny, brown, one-seeded fruit (achene) about 1/10 of an inch (3 mm) in length is attached to a long, slender stalk, terminating in a parachutelike structure (pappus) consisting of hairs. Collectively the fruit form a fuzzy, gray-white, spherical fruiting head.

Seed

Seeds are transported by wind.

Reproduction

Reproduce by seeds that can germinate almost year-round. Taproots can also send off new shoots.

Related species/Similar looking plants

Annual sowthistle
Common catsear

More information

• Broadleaf ID illustration
• Calflora's distribution map
• See UC IPM's Pest Management Guidelines for agricultural information
• See UC IPM's Dandelions Pest Note for landscape information