Pimelea, commonly called riceflower, is a genus of plant found in Australia and New Zealand. There are approximately 80 species in the genus, most of which are shrubs. Difficult to grow from seed, only a few species of this flowering plant are commonly cultivated. Though it poses no threat to humans, when the leaves are eaten by cattle, sheep and horses, they can cause gastro-intestinal problems and occasionally death.
A member of the Thymelaeaceae family, most Pimelea are flowering shrubs, though some species grow in the form of long-stemmed, woody vines. Thymelaeaceae are widespread throughout tropical and temperate climates, with the majority of species endemic to the Southern hemisphere. Most Pimelea species are native to Australia, New Zealand, and neighboring islands. These plants grow in a range of habitats, from the torpid jungles in the north of Australia, to the cool mountainous regions on the southern island of New Zealand. Each species is picky about where it grows, however, so most individual species have a narrower range of acceptable habitats.
While many species are difficult to grow, there are a few that are commonly used in landscaping. The plants produce small, inedible fruits that contain their seeds, but these seeds do not germinate easily. Plants are best cultivated through cuttings that can be planted in soil or grafted to hardy rootstalk.
Some of the more common varieties include Alpine Rice-Flower, or Pimelea alpina, and Yellow Rice-Flower, or Pimelea flava, which are both endemic to Southern Australia. Alpine Rice-Flower, as its name suggests, grows in cooler, alpine regions and displays clusters of five to 18 pink or white flowers at the ends of its branches. Remaining relatively small, Alpine Rice-Flower grows to heights of only about 1 foot (30 cm). Yellow Rice-Flower grows to 6.5 feet tall (about 2 m), and has similar clusters of yellow flowers at the ends of its long stalks.
Pimelea poses a problem for ranchers in Australia. In the early 1970’s, three species were officially recognized as the culprit in livestock deaths. Poisonings from consuming Pimelea cost millions each year in lost livestock and veterinary treatment. Though the plant has a strong odor and is not normally selected by livestock for food, it can be inadvertently eaten when mixed in with grasses. Symptoms of Pimelea poisoning manifest as gastro-intestinal problems and, in cattle, swelling under the jaw and on the chest. Livestock that eat this plant can also die suddenly due to heart failure.