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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

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

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
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		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
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		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
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		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 is from the Wikimedia Project. Locally common, robust annual mostly in riparian habitats or irrigation ditch banks. Broad leaves. Distinct bur. Detailed Description		Pinnately disected leaves. Spkies of separate male and female flower heads appear yellowish due to much pollen. Herbaceous perennial forming colonies. Detailed Description