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Brittle Bush
Gall Midge
Encelia Leaf Beetle

Encelia farinosa

Asphondylia sp.

Trirhabda geminata

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Watercolor © by Michael Plagens

This watercolor was done from a live specimen found in the McDowell Mts., Maricopa Co., Arizona, USA. Feb. 9, 1992.

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FLOWERS: Bright yellow and very showy ray flowers. Even meager winter rainfall will result in a magnificent show of large vivid yellow flowers on this perennial. The disc flowers are darker yellow, sometimes brownish, depending on the variety.

SHRUB: The above ground branches frequently die back after prolonged drought or a severe freeze so that by late February through March the landscape is dotted with dense green shrubs of nearly uniform height (ca. 1 m) topped by abundant yellow flowers. No wonder landscapers have discovered the attractiveness of this native plant.

RANGE: This plant is a characteristic component of the flora throughout the Sonoran Desert. Brittle Bush grows best where it gets added moisture as runoff from roads or adjacent impervious rock. Many plants grow back from the roots after brush fires and often dominate burned slopes for many years hence.

LEAVES: The leaves are covered with varying amounts of long or short silky trichomes (hairs) that give a silvery appearance. Crushed foliage exudes a pleasant terpene odor while damaged twigs slowly exude a golden resin that eventually dries to form glistening globules. This resin has been used as a substitute for incense, and so the Spanish name Inciensio.

ACHENE: The achene lacks a pappus , and is covered by a short pubescence. Each achene is subtended by a papery bract.

Trirhabda geminata photo by L Nessel. Click for larger photo and description. Several insects have specialized on eating Brittle Bush leaves. A tiny gall midge (tiny fly, Cecidomyidae) causes fuzzy enlargements on young leaves or stems where the maggot developes inside. Leaf beetles (Trirhabda geminata) sometimes become so abundant that every bush seems to be ravaged by the black, 7 mm long larvae. Cool, damp winters sometimes result in exploding aphid populations, which in turn host numerous lady bird beetles. Lady bird larvae resemble miniature gila monsters. Each lady bird larva consumes numerous aphids as it develops. Several species of brightly colored blister beetles occasionally appear in mass to feed on the tender petals. In addition, the caterpillars of the Painted Lady Butterfly can appear in large numbers on this plant.

Asteraceae -- Sunflower Family

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Copyright Michael J. Plagens, 1999-2011