Bidens alba (L.) DC.

Beggarticks; Romerillo

Herb

Annual

Vascular

Shepherd's Needle is a herbaceous annual or short-lived perennial in the Sunflower family (Asteraceae). It can be found primarily in the southern half of the state. Shepherd's Needle grows on dunes, in disturbed sandy woodlands, in vacant lots, and on roadsides. It is an annual or short-lived perennial with a tap root. The lower branches sometimes root at the nodes when in contact with the soil. The stems are square, green in color, erect or decumbent at the base, and glabrous or pubescent towards the apex. Leaves are opposite, petiolate, and ternately to pinnately lobed. The lobes are lanceolate to ovate in outline, serrate, and pubescent on the lower surface. Flowers are produced in heads. The heads are solitary or in corymbs. Each head has 0-8 white ray flowers and 20-60 yellow disc flowers. The fruit is a fusiform achene with 2 retrorsely barbed awns. Shepherd's Needle is sometimes available from native plant nurseries as seed. It prefers a well-draining soil in full sun. It should be planted away from well-traveled areas as the seed will readily attach to clothing and animal fur. It is frost sensitive, and will have to be grown as an annual in most of Alabama. Shepherd's Needle bloom profusely in the late autumn and attracts many butterflies and other insects. It is a vector for root nematodes and tomato spotted wilt virus, so it should not be planted in garden plots or in beds with other plants. Shepherd's Needle contain a wide variety of phytochemicals that have been used in traditional medicine. The crushed leaves have been applied to wounds for their antibiotic properties, and parts of the plant have been consumed as a vegetable.--A. Diamond

Bidens alba is probably not native to Alabama. When Mohr published "Plant Life of Alabama" in 1901, he remarked that he only knew it as a "fugitive on ballast" referring to the old ballast ground in and around Mobile. That limitation is certainly not the ubiquitous weed we know today throughout most of the coastal plain especially pernicious in the outer coastal plain.|||| Bidens alba is part of the "pilosa complex" which includes neotropical taxa some of which have expanded their range into the SE US. True Bidens alba (in the strict sense) produces two awns on the cypselae and produces white rays often 1 cm or more long. The other species in our flora is Bidens pilosa, which typically produces three awns on the cypselae and does not produce rays or if so they are 3 mm ore more long. Some specimens have been observed to have the longer rays but with a third reduced awn on the fruit. This may indicate some introgression among both of the non-native taxa. Several specimens here and under B. pilosa need to be reevaluated and assigned to the correct taxon accordingly.--B.R. Keener

Not Native FACW- (NWPL)

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