Scientific Name: Bidens bipinnata

Common Name: Spanish needles

Synonyms: Bidens bipinnata var. biternatoides

Habit: Summer annual with dissected leaves and yellow flowers reaching 5 1/2 feet in height.

Leaves: The leaves are dissected with 2 to 3 rows of lateral leaflets that are ovate or lanceolate in shape. The leaves have short hairs along the edges and veins that are pressed closely to the leaves.

Identifying Characteristics: Stems: Erect, square in cross-section, branching in the upper section, and with small tufts of hairs at the nodes. Summer annual with leaves that are dissected 2 to 3 times and have yellow flowers. Spanish needles seedlings are similar in appearance to those of Common Ragweed (<a href='../../weedimg/69'>Ambrosia artemisiifolia</a>), however the cotyledons of common ragweed are much more rounded than those of spanish needles. Additionally, common ragweed seedlings do not have the characteristic maroon highlights on the cotyledon and leaf undersurfaces like those of spanish needles. Devils Beggarticks (<a href='../../weedimg/235'>Bidens frondosa</a>) is also similar in appearance to spanish needles; devils beggarticks does not have leaves that are dissected 2 to 3 times, however. Spanish needles can also be confused with Coreopsis Beggarticks (Bidens polylepis). Coreopsis beggarticks, however, has flowers that are much larger and showier and leaflets that are more linear than those of spanishneedles.

Flower Seed Head: The yellow flowers are composed of small disk flowers toward the center, and larger ray flowers along the edge. Occasionally, the ray flowers will be absent, but are usually 10 to 15 mm long and 3 mm wide. The flowering heads are often surrounded by green bracts.

Seed Fruit: The seeds develop in an achene that is approximately 8 to 18 mm long, linear in outline, and dark brown in color. The achenes have 3 to 4 spines at the apex that are pointed downward.

Where Found: Spanish needles prefer dry waste places such as roadsides, pastures, and other noncrop areas. It can be found along the eastern United States.

  • Life cycle: biennial

  • Milky sap: Not Present

  • Plant type: Herb

  • Thorns: Not Present

  • Plant family: Fabaceae

  • Leaf arrangement: opposite

  • Leaf shape: lance; oval

  • Ochrea: Not Present

  • Leaf margin: lobed; serrated

  • Stem hairs: has hairs; no hairs

  • Flower color: orange; yellow

  • Growth habit: upright and nonwoody; prostrate and nonwoody

  • Stem: round or oval

  • Leaf structure: simple

  • Leaf hairs: has hairs; no hairs

  • Flower diameter: pencil

  • Flower symmetry: not symmetrical; bilateral symetry

  • Root structure: fibrous

  • Leaf stalk: longer than leaf; shorter than leaf