Beach Wormwood (Artemisia campestris caudata)

Description: This plant is a biennial or short-lived perennial. During the 1st year, a rosette of basal leaves is produced. The basal leaves are up to 4" long and 3" across; they are deeply pinnatifid or bipinnatifid with narrow linear lobes (up to 2" long and less than 1/8" across). They have long petioles. During the 2nd and later years (if any), this plant bolts to become 1½-3½' tall, while the rosette of basal leaves withers away. The central stem and ascending lateral stems are light green to dark red, terete, and longitudinally veined. Usually the young tips of stems are tomentose (with short white cobwebby pubescence), otherwise they are mostly glabrous. The cauline leaves alternate along these stems; they are more common along the lower central and lower lateral stems. The lower cauline leaves resemble the basal leaves, except they have short petioles. Middle cauline leaves are smaller in size and less divided into linear lobes, while the upper cauline leaves are short (less than 1" long) and linear in shape. The upper surfaces of the narrow leaf lobes are whitish green, flat, and tomentose, becoming more glabrous with age. The lower surfaces of the leaf lobes are light to medium green, rounded (convex), and glabrous. The foliage is not strongly aromatic.

The upper stems terminate in narrow panicles of flowerheads about 4-16" long. Upper cauline leaves occur along these flowering stalks. Individual flowerheads are whitish green or yellowish green and about 1/8" (3 mm.) long and similarly across. Each flowerhead has 8-30 inner florets that are perfect and 5-20 outer florets that are pistillate. Each inner floret consists of a narrow tubular corolla with 5 teeth along its upper rim, some fertile stamens, and an abortive ovary that is sterile. Each outer floret consists of a narrow tubular corolla with 2-3 teeth along its upper rim and a fertile ovary with a divided style. At maturity, the flowerheads droop downward from short pedicels. The base of each flowerhead is surrounded by appressed bracts (phyllaries); individual bracts are lanceolate to ovate and up to 2 mm. long. The blooming period occurs from mid-summer to early autumn for about 2-3 weeks. The florets are cross-pollinated primarily by the wind. The outer florets of the flowerheads are replaced by bullet-shaped achenes about 0.8-1.0 mm. in length; the achenes are without tufts of hair or a crown of Distribution Map

scales. They are usually distributed only a short distance from the mother plant by the wind. The root system consists of a woody taproot or caudex with lateral roots. This plant reproduces by reseeding itself.

Cultivation: The preference is full sun, dry conditions, and sandy soil. During hot dry periods, it is not uncommon for the lower leaves to wither away. This plant has some tolerance to road salt.

Range & Habitat: Beach Wormwood is occasional in northern Illinois and also in the central section of the state along the Illinois River; otherwise it is rare or absent. Only ssp. caudata occurs within the state; the typical subspecies is found in Europe. Habitats include semi-stabilized sand dunes along Lake Michigan, dry areas of beaches, dry sand prairies, openings in sandy savannas, rocky glades, ledges along cliffs, sand bars and gravel bars along major rivers, abandoned sandy fields, and sandy roadsides. Beach Wormwood prefers sandy areas where there has been some disturbance from wind or wildfires.

Faunal Associations: To a limited extent, Beach Wormwood may be cross-pollinated by small bees and flies seeking pollen from the flowerheads. The foliage is sometimes eaten by Melanoplus foedus (Striped Sand Grasshopper), Melanoplus keeleri (Keeler's Grasshopper), and other grasshoppers that inhabit barren sandy areas. Other insect feeders include the caterpillars of Phaneta argenticostana (Tortricid Moth sp.) and Schinia nuchalis (Spotted Clover Moth), which feed on the seedheads and flowerheads; the caterpillars of the butterflies Vanessa cardui (Painted Lady) and Vanessa virginiensis (American Painted Lady); the plant bugs Europiella bakeri and Lygus atritibialis; and the aphid Macrosiphoniella ludovicianae. Because of its bitter taste and mild toxicity, cattle and other mammalian herbivores in the Midwest avoid consumption of this plant. However, vertebrate wildlife in the western states make greater use of Artemisia spp. as sources of food.

Photographic Location: A sand dune along Lake Michigan at Indiana Dunes State Park in NW Indiana.

Comments: Beach Wormwood is the primary host of a rare parasitic plant, Orobanche fasciculata (Clustered Broomrape). The pale flowering stalk of this parasitic plant can be observed near Beach Wormwood during late spring or summer. A similar species, Orobanche ludoviciana (Prairie Broomrape), is also parasitic on Beach Wormwood, but this latter species is parasitic on a variety of other species in the Asteraceae. Among the several Artemisia spp. in Illinois, Beach Wormwood can be identified by the toothless linear lobes (less than 1/8" across) of its deeply divided leaves. It is also unusual in having perfect florets with sterile ovaries, which are normally fertile in other Artemisia spp. Another common name of Artemisia campestris caudata is Field Sagewort. A scientific synonym of this species is Artemisia caudata.