Petasites frigidus var. palmatus, sometimes referred to as P. palmatus, palmate coltsfoot, or western coltsfoot; a.k.a. Arctic sweet coltsfoot or Arctic butterbur.
The leaf stalks and flower stems (with flowers) are edible, and can be used as a vegetable dish. A salt-substitute can also be made by drying and then burning the leaves. This black, powdery substance will provide a salty taste. However, given the high likelihood of the presence of toxic unsaturated, diester pyrrolizidine alkaloids in this species, consumption should be very limited.
...long-standing use as a treatment for bronchial ailments such as coughing, bronchitis and asthma. The leaves and sometimes flowers may be concocted to syrup or cough drops or simmered to make tea. The leaves were also traditionally smoked to alleviate asthma though modern medicine discourages smoking. Tea made from the leaves is astringent and may also be used to treat insect bites and burns. Petasite palmatus root and leaves have also been used to treat cough, asthma and congestion. Indigenous peoples in North America have eaten the roots and stems and used them to treat intestinal and bronchial ailments, tuberculosis and as a poultice to relieve inflammation and sprains. As with any herbal remedy, caution should be taken, especially before administering to children. Some research has shown ... plants may be harmful if ingested.
--SFGATE Home Guides , http://homeguides.sfgate.com/coltsfoot-weed-80194.html