Get to Know Your Grasslands: Downy Paintbrush

Hidden in the grasslands, tucked among the grasses, a unique forb thrives in the hot, dry conditions of southern Saskatchewan’s native grasslands. With its fused petals forming an unusual shape and colors ranging from soft pink to pale yellow, it’s both eye-catching and surprisingly elusive. This rare beauty is known as the Downy Paintbrush (Castilleja sessiliflora), a species native to the Great Plains, including parts of southern Saskatchewan and Alberta.

The genus Castilleja, commonly known as “Indian Paintbrush,” includes around 200 species worldwide, most of which are native to western North America. The Downy Paintbrush (Castilleja sessiliflora) ranges from southern Canada through the central United States and as far south as northern Mexico. Of the 200 global species, 24 are found in Canada, primarily in British Columbia and Alberta, with some extending into the southwestern corner of Saskatchewan. Saskatchewan is home to one species of paintbrush, Orobanacheae Castilleja sessiliflora. The species is known to a variety of common names including:

• Downy Paintbrush
• Downy Painted Cup
• Indian Paintbrush
• Downy Yellow Painted Cup
• Yellow Indian Paintbrush
• Large Flower Indian paintbrush

Downy paintbrush produces one or more stems from a woody root crown. It can be recognized by its fused petals, short sepals, and an inflorescence (flower cluster) that can vary from pink, to yellowish, and even green. The stems and leaves are covered in tiny hairs, making them appear fuzzy. Flowers can be observed blooming in the months of May and June and set to seed in July and August. This paintbrush was photographed in early June near Rockglen, Saskatchewan. Unlike more vibrant paintbrush species, the downy paintbrush has a more subdued but still striking appearance.

Downy paintbrush, like many other species of paintbrush, is a hemiparasitic plant. Meaning that it can photosynthesis on its own but also steals nutrients and water from a host plant. They are able to do this through a specialized root structure called haustoria that connects to the roots of other host plants that are often nearby grasses or forbs. Through these haustoria, the Indian paintbrush siphons off water and dissolved minerals from its host, giving it a boost, especially in poor soils or times of drought.

Due to this special adaptation, this species requires minimal water and thrives in dry prairie with full sun exposure. Suitable host plants for downy paintbrush include grass species such as blue grama , june grass , and sedge species. They are typically found in rocky or sandy soil and on open hillsides but are tough to find and are classified are rare in Saskatchewan..

Downy paintbrush is a subtle but ecologically important part of Canada’s prairie ecosystems. Its unique adaptations and limited distribution make it a valuable species for conservation. Protecting the biodiversity and health of native prairie landscapes is one way to ensure this unique flower will also be protected.

 

Author: Janna Hewitt

& Mindy Hockley-Anderson