Rowan Several of the Asian species are widely cultivated as ornamental trees. North American native species in the subgenus "Sorbus (Sorbus)" include the American mountain-ash "Sorbus americana" and Showy mountain-ash "Sorbus decora" in the east and Sitka mountain-ash "Sorbus sitchensis" in the west. Numerous hybrids, mostly behaving as true species reproducing by apomixis, occur between rowans and whitebeams; these are variably intermediate between their parents but generally more resemble whitebeams and are usually grouped with them (q.v.). Rowans are excellent small ornamental trees for parks, gardens and wildlife areas. Several of the Chinese species, such as White-fruited rowan ("Sorbus glabrescens") are
Insecticidal soap at higher concentrations or at temperatures above 32 °C (90 °F). Plant injury may not be apparent until two days after application. Some plant species are particularly sensitive to soap sprays. Highly sensitive plants include: horse chestnut, Japanese maple ("Acer"), "Sorbus aucuparia" (mountain ash), Cherimoya fruit, "Lamprocapnos" (bleeding heart), and sweet pea. Other sensitive plants are, for example: "Portulaca", some tomato varieties, "Crataegus" (hawthorn), cherries, plum, "Adiantum" (maidenhair fern), "Euphorbia milii" (crown of thorns), "Lantana camara", "Tropaeolum" (nasturtium), "Gardenia jasminoides", "Lilium longiflorum" (Easter lily). Conifers under (drought) stress or with tender new growth are sensitive as well. Damage may occur