Plant Name

Scientific Name: Ambrosia confertiflora

Synonym: Franseria confertiflora

Common Names: Weakleaf Bur Ragweed, Weakleaf Burr-Ragweed, Slimleaf Bursage, Slender Ragweed

Plant Characteristics

Duration: Perennial

Growth Habit: Herb/Forb

Arizona Native Status: Native

Habitat: Desert, Upland

Flower Color: Dull yellowish, Greenish

Flowering Season: Spring, Summer, Fall

Height: To 3 feet (91 cm) tall, but usually less

Description: The staminate (male) flower heads are in terminal and lateral flower spikes, while the pistillate (female) flower heads are clustered below them at the leaf axils. The flowers are wind-pollinated and are followed by burs with a few, short, hooked spines. The leaves have petioles with lobed wings and are grayish green in color, mostly alternate, covered in silky grayish hair, lanceolate to ovate in shape, and 2-4 pinnately lobed with narrowly lanceolate lobes. The upright stems grow from rhizome-like roots and are hairy or bristly and green to reddish brown in color.

These weedy plants are often found growing in disturbed areas.

Special Characteristics

Allergenic – The male flowers have highly allergenic pollen.

Classification

Kingdom: Plantae Plants
Subkingdom: Tracheobionta Vascular plants
Superdivision: Spermatophyta Seed plants
Division: Magnoliophyta Plants
Class: Magnoliopsida Dicotyledons
Subclass: Asteridae
Order: Asterales
Family: Asteraceae Aster family
Genus: Ambrosia L. – ragweed
Species: Ambrosia confertiflora DC. – weakleaf bur ragweed