Arrowleaf Senecio

It is similar in form to Senecio serra, both being four feet tall, have narrow and serrated leaves, and are topped with many small, yellow sunflowers. but S. triangularis is more common. S. triangularis has single erect stems, reaching up to 10–120 cm (4–47 in) tall. The stems have evenly distributed leaves. The leaves are up to 20 cm (8 in) long and triangular with tapered ends, hence the name. The green involucral bracts have black tips with hairy tufts. On display from June to September, the yellow flower heads are up to 4 cm (1+1⁄2 in) wide, with about 8 rays around a disk. As some plants are diploid, meaning having two sets of chromosomes; this can be used to identify hybrids and classification of groupings. It has been counted as 2n = 40, 80.

It is native to temperate regions of America:

Nearctic: Subarctic America: Northwest Territory, Yukon Territory, Alaska Western Canada: Alberta, British Columbia Northwestern United States: Colorado, Idaho, Montana, Oregon, Washington, Wyoming Southwestern United States: Arizona, California, Nevada, Utah, New Mexico It grows in open woodlands, (mainly coniferous forests) and on rocky stream sides. They can grow at altitudes of between 100 and 3,500 m (330 and 11,480 ft).