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Sonoran Desert Asters - Flowers Non-Showy

Mostly shrubs, many perennials, few herbaceous annuals with flowers in heads that have no obvious petals or bright colors. Phyllaries (the bracts surrounding the heads) are typically green or brown and are scarious, papery, or burlike. Flowering head may appear yellow due to abundance of pollen; male and female flowers often in separate heads or on separate plants. Usually wind pollinated and often a source of hay fever.

Canyon Ragweed

Ambrosia ambrosioides

Triangle-leaf Bursage

Ambrosia deltoidea

Watercolor by Michael Plagens

Robust perennial growing as many few-branched stems arising from a basal crown to a height of a meter +. Large, serrate, triangular leaves that remain green well into drought periods. Grows commonly along sandy washes and in canyons. Seeds inside a bur. Male flower heads above female on spike. Detailed Description

Pen and Ink by Mike Plagens

Abundant shrub on desert flats and rocky slopes about ½ m tall. Smaller, triangular, deciduous leaves. Seeds in a bur. Male flower heads above female on spike. Detailed Description

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White Bursage

Ambrosia dumosa

Wooly Bursage

Ambrosia eriocentra

Pen and Ink by Michael Plagens

Common shrub in lower elevations of Sonoran Desert found on desert flats. Leaves are almost white, pinnately divided, and pleasantly aromatic. Seeds inside a bur. Male flower heads above female on spike. Detailed Description

Pen and Ink by Mike Plagens

Locally common shrub of desert washes along the northern flanks of the Sonoran Desert where it is meeting chaparral. Disected leaves are pungently aromatic. Bur is beset with wooly hairs. Male flower heads above female on spike. Detailed Description

Burro Bush

Hymenoclea salsola

Tucson Bur Ragweed

Ambrosia cordifolia

Pen and Ink by Michael Plagens

Common shrub along washes and in riparian habitats especially where there is heavy grazing pressure. Leaves linear, thread-like. Huge clusters of flowers at branch tips. Papery bracts can take on beautiful burgandy or golden hues. Seeds surrounded by ring of bracts. Abundant pollen cause of hayfever. Detailed Description

Pen and Ink by Michael Plagens

Toothed, heart-shaped leaves. Found in canyons along southern tier of the Sonoran Desert in Arizona, esp. near Tucson. Detailed Description

Desert Twinbugs

Dicoria canescens

Holly-leaf Bursage

Ambrosia ilicifolia

Photo by Michael Plagens

A tall annual found along washes and river flood plains where there is deep, sandy soil. Blooms late fall into winter. Very pungent (disagreable?) aroma. Small heads of small yellow-appearing (due to much pollen) flowers. Seeds surrounded by enlarged papery bracts. Detailed Description

Photo by Michael Plagens

Sharply serrate leaf margins. Found at low, hot areas of the Sonoran Desert. Leaves remain on plant several seasons bleaching. Detailed Description

Cocklebur

Xanthium strumarium

Weak-leaf Bur Ragweed

Ambrosia confertiflora

Photo by Mike Plagens

Photo is from the Wikimedia Project. Locally common, robust annual mostly in riparian habitats or irrigation ditch banks. Broad leaves. Distinct bur. Detailed Description

Photo by Michael Plagens

Pinnately disected leaves. Spkies of separate male and female flower heads appear yellowish due to much pollen. Herbaceous perennial forming colonies. Detailed Description

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