Included in the Asteraceae family, the haplopappus plant genus includes a selection of North and South American herbs and shrubs that produce yellow flowers. Historically, the haplopappus genus was used as a wastebasket taxon to include plants in the Astereae tribe that could not be placed in any other classification. Since 1990, most of these miscellaneous species have been reclassified to the correct genus and removed from the haplopappus category.
Haplopappus heterophyllus, also known as rayless goldenrod or jimmy weed, is a bushy, branchless perennial shrub with yellow flowers that grows up to five feet (1.5 meters) tall. It is native to the dry rangelands in the southwestern U.S. and is often found in river valleys and drainage areas. Both the green and dry plant materials contain a toxic chemical called trematone that will poison horses, cattle, sheep, and goats when consumed. If lactating animals eat jimmy weed, the milk becomes contaminated and causes milk sickness in the nursing young.
Narrowleaf goldenweed, or Haplopappus stenophyllus, is a perennial shrub native to the western U.S. that produces bright yellow flowers in mid to late spring. The daisy-like flowers are one inch (2.5 cm) in diameter with six petals radiating from the center. Its small, rough leaves are narrow and cover the stem. The narrowleaf goldenweed grows well on steppes and grasslands.
Thrifty goldenweed, or Haplopappus armerioides, is a perennial herb with short stems that vary in height. Each stem produces eight to 13 tiny yellow flowers. The flower head appears to be one larger bloom, but is a composite flower made of several smaller ones. This plant is also known as ring grass because of its growing pattern. It grows outward from a central ring that may be dead within the center.
The Haplopappus foliosis is a shrub that is native to Chile and grows in dry, coastal, or coastal mountain regions. It can thrive in full sun or partial shade and grows best on level ground or north-facing slopes. The yellow flowers produce at least 14 petals and have limited ornamental value. These flowering plants are easy to cultivate, but do not tolerate any freezing temperatures.
Also native to Chile, the Haplopappus macrocephalus is a much shorter perennial flower that grows in that country's interior valleys. It grows best in dry conditions with full sun exposure. Like H. foliosis, it thrives on level ground or north-facing slopes. The stems produce a single orange and golden-yellow flower with 14 or more petals.