Taraxacum officinale is a perennial C3 herb (Pooter et al. 1990), from a tap root to 2 m long, 2-3 cm diameter, plants capable of regenerating from short segments of root; reported to form VA mycorrhizal associations with Glomus mosseae (Zygomycotina) and Pythium ultimum (Mastigomycotina, oomycetes); sap white; plants may live more than 13 years (Agrios 1988; Smith and Read 1997; Stewart-Wade et al. 2002); leafy stem very short, 1-2.5 cm.
Leaves alternate in a basal rosette, overwintering (Levine 1995), very variable, 5-40 cm long, 0.7-15 cm wide, elongate, deeply toothed or lobed, widest above middle, base tapered to winged stalk, midrib yellowish to dark reddish.
Flowers yellow, in a head 2-5 cm wide, all rays, up to 250 florets, petal tip toothed; although dandelion produces nectar and both nectar and pollen are taken by taken butterflies, bee flies, hawk moths, flies, honey bees, bumble bees, beetles and numerous other insects, pollen is sterile and seeds develops without fertilization (agamospermy/apomixis); in Asteraceae, ray flowers are most often sterile (Mulligan and Kevan 1973; Stewart-Wade et al. 2002 ), bracts of flower head 2 rows, green to brownish, outer bracts bent outward, shorter and wider than inner bracts, heads solitary at ends of hollow, leafless, unbranched, pale stalks 5-50 cm long, blooms when day length is 12-13 hours, late April-June and sometimes again in autumn; flower heads open for 2-3 days, then close, the flower stem flattens to the ground, then straighten up and elongate in seed; blooms Mar.-Dec. (Hough 1983).
Fruit dry, 1-seeded (achene), 0.3-0.5 cm long, plume bristles white, to 0.4 cm long, ripe, plumed achenes collectively ball-shaped on flower stalk, wind dispersed but also dispersed in droppings of herbivorous animals. Seeds eaten by many birds including house finches, goldfinches, sparrows and by small mammals. Foliage and flowers eaten by rabbits, chipmunks, woodchucks, deer, ducks, Canada geese, pheasants, also by ants, slugs, snails, juvenile earthworms and other invertebrates (Martin et al. 1951; Stewart-Wade et al. 2002). Seeds can remain viable in soil up to 30 years. Seedlings may bloom the first year but usually do not until the second year. Seeds produced in spring emerge the same season, seeds produced in fall emerge the next spring (Uva et al. 1997).
Wetland status: FACU-.
Frequency in NYC: Very common (more so than indicated above).
Habitat: Weed of open, disturbed places, lawns, roadsides, agricultural fields. Tolerates part shade. Prefers moist, high nutrient soils, but tolerates soil pH 4.8-7.6.
Notes: Seedlings cannot establish on very dry soils but larger plants are drought tolerant. “Used as a medicinal plant, however, overindulgence may render the liver inactive and cause various unpleasant symptoms” (Stewart-Wade et al. 2002). Used particularly for its diuretic properties. Leaves and roots also accumulate various heavy metals including lead, zinc, mercury and copper and has been used to detect bioavailability of trace metals. Dandelion pollen is an allergen in honey. However, the greens and roots are edible and widely used. Leaves are highly nutritious. Bitterness of leaves, especially after formation of flower buds, caused by sesquiterpene lactones and other phenolic compounds that probably act as feeding deterrents to insects and other herbivores. Phenolic compounds also act as allelopathic agents that inhibit germination of seeds and have anti-fungal properties. Dandelion roots store carbohydrates as fructans, such as inulin, in autumn for growth in the spring, they also store unsaturated fatty acids as antifreeze agents for over wintering; rosette habit of leaves suppresses competition from nearby plants (Stewart-Wade et al. 2002; Harborne 1988). Insect predators include; the cynipid wasp Phanacis taraxaci which forms leaf, gall tissues pull nutrients away from leaves without galls; the green peach aphid, Myzus persicae (Aphidae, Homoptera), a very common insect that attacks Prunus sp., it overwinters as a shiny black egg on the bark of trees; the minute seed weevil, Ceutorhynchus punctiger (Curculionidae, Coleoptera), which damages flower buds, seeds and leaves; the larvae of several moths (Lepidoptera) in the family Noctuidae, including the cabbage looper, Trichoplusia ni, the yellow-striped army worm, Spodoptera ornithogalli, both common crop pests, and Diacrisia virginica, which normally feeds on grasses but prefers dandelion. Dandelion is host to the dagger nematodes Xiphinema americana and X. rivesi, both known to transmit plant viruses. Numerous fungi have been found on dandelion including Puccinia taraxaci, a rust (Basidiomycotina) that forms tiny dark brown blisters on leaves, and Synchytrium taraxaci, (Mastigomycotina, Chytridiomycetes), which causes tiny swellings on leaves. A long list of bacteria and viruses have also been isolated from T. officinale (Borer and White 1970; Covell 1984; Agrios 1988; Johnson and Lyon 1991; Stewart-Wade et al. 2002).Taraxacum officinale.Paul.www.tidygardens.eu .