BRITTLE BUSH
GALL MIDGE
Encelia Leaf Beetle
Encelia farinosa
Trirhabda geminata
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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. Even meager winter rainfall will
result in a magnificent show of large vivid yellow flowers on this perennial.
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.
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 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.