Asphodelus fistulosus

Species

Asphodelus fistulosus L.

Family

Asphodelaceae

Common names

onionweed, asphodelus, wild onion

Disseminule

seed

Description

Fruit a 3-valved capsule, with 1 to 2 seeds per valve. Seeds sectoroid, (2.5)2.8–3.5(4.0) mm long, 1.5–2.5(2.8) mm wide, 1–2 mm thick, triangular to sector-shaped in cross section, with sharp edges. Two flat faces with 2 to 3 or more dents or cavities on each, back side convex with about 4 transverse dents or cavities. Testa dull, light to dark grey and light brown to black. Some seeds have a faint to distinct black stripe down each flat face. Surface distinctly and minutely papillate. Hilum inconspicuous. Embryo axile-linear, extending from one pole nearly to the other; endosperm readily visible.

Identification considerations

Some authors consider Asphodelus fistulosus L. to be a distinct species from Asphodelus tenuifolius Cav., while others consider the two to be synonymous. (This fact sheet considers the two species to be distinct.) Additionally, Asphodelus fistulosus var. tenuifolius (Cav.) Baker has been named a synonym of Asphodelus tenuifolius Cav.

APHIS conducted a weed characterization and a weed risk assessment of the federal noxious weed A. fistulosus in 2018 and 2019, respectively. Authors found limited evidence that A. fistulosus is present in India, even though U.S. port inspectors frequently intercept A. fistulosus as a contaminant in cumin from India. It has been suggested that these interceptions are likely not A. fistulosus, but rather A. tenuifolius, which is not a federal noxious weed. The size ranges of the two species’ seeds overlap substantially, based on measurements in the literature of only seeds originating in the Mediterranean region. The seeds of these two species may differ in length by about 0.5 to 1 mm, with the seeds of A. tenuifolius being smaller, but this difference in seed size is not a reliable way to distinguish the species.

Similar species

Asphodelus tenuifolius Cav. (non-FNW)

Distribution

Native to the Mediterranean region east through the Arabian peninsula; naturalized in Argentina, Australia, Bolivia, Chile, Mexico, New Zealand, United Kingdom, and United States.

Habitat

dry, sandy, and rocky places; a weed of pastures, roadsides, waste places

General information

Asphodelus fistulosus is an annual or perennial herb, up to 30 cm tall. Infestation may significantly reduce the carrying capacity of pasture, as it is not eaten by livestock. This species can be controlled by cultivation; it does not grow well on land that is regularly worked. The plant occurs in a few places in the U.S., but no infestations have been reported.