Summary[edit] Description: Sticky leaf arnica, Rayless arnica (Arnica ovata syn. Arnica ×diversifolia [amplexicaulis or mollis × cordifolia or latifolia]), Aster family (Asteraceae). Logan Canyon, Utah. This is an interesting plant. I never saw such long and widely winged petioles of the upper leaves. Most of Arnicas have sessile or very shortly petiolate upper leaves. Logan Canyon is really great place!. Date: 30 May 2015, 14:46. Source: 2015.05.30_14.46.03_IMG_2564. Author: Andrey Zharkikh from Salt Lake City, USA.