skeletonleaf bursage
Ambrosia tomentosa Nutt.


Ambrosia tomentosa' is a long lived perennial herbaceous plant in the sunflower family (Asteraceae) growing up to 3 ft (0.91 m) in height. A. tomentosa develops extensive horizontal roots. It is native to the Great Plains region.
A. tomentosa leaves are alternate, up to 5 in. (12.7 cm) long. They are finely dissected and deeply lobed with coarsely toothed margins. The upper leaf surface is greenish-gray and may have rough hairs. The lower leaf surface is covered with white short, dense hairs.
The yellow flowers of A. tomentosa are very small and inconspicuous. The male flowers are held in umbels at the top of the stem while the spiny female flowers are found in the leaf axils. The spiny female flowers help to set this species apart from other Ambrosia species.
A. tomentosa fruits are light brown burs with up to 10 short spines. They each contain 2 seeds. A. tomentosa also reproduces vegetatively by sending shoots up from the horizontal root system.
Ecological Threat
A. tomentosa is considered a serious cropland weed. It spreads both by seed and creeping roots, keeping primarily on, but not limited to, dry or poorly drained sites. A. tomentosa can be found growing in cultivated fields, pastures, prairies, and waste areas.

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EDDMapS Distribution

EDDMapS Distribution - This map is incomplete and is based only on current site and county level reports made by experts, herbaria, and literature. For more information, visit

State Regulated List

State Regulated List - This map identifies those states that list this species on their regulated list. For more information, visit

Invasive Listing Sources

Taxonomic Rank

Kingdom: Plantae
Phylum: Magnoliophyta
Class: Magnoliopsida
Subclass: Asteridae
Order: Asterales
Family: Asteraceae
Genus: Ambrosia
Subject: Ambrosia tomentosa Nutt.

Synonyms and Other Names

Other Common Names:
skeletonleaf burr ragweed, skeleton-leaf burr-ragweed, skeletonleaf bursage


Plants - Forbs/Herbs