Fraxinus uhdei, commonly known as tropical ash or Shamel ash, is a species of tree native to Mexico and Central America.[2] It is commonly planted as a street tree in Mexico and the southwestern United States. It has also been planted and spread from cultivation in Hawaii, where it is now considered an invasive species.
Fraxinus uhdei is a fast-growing, medium to large tree (up to 35-40 m tall and 1 m stem diameter) that grows naturally in mixed mountain forests from west-central Mexico to Costa Rica. It has been introduced to Hawaii, Puerto Rico and sub-Himalayan regions of India for watershed protection and timber production. It is also a popular street and shade tree in California, Arizona and Mexico. F. uhdei is shade tolerant and a prolific seed producer, and has become highly invasive in Hawaii where it has spread from cultivation into disturbed forest areas. Based on the description given by Wagner et al. (1999) as reported by PIER (2016), F. uhdei is a forest tree up to 35-40 m tall and up to 1 m in trunk diameter, with furrowed grey or brown bark, producing a canopy 9-13 m wide. Young branches are pubescent, soon glabrate. Leaves are 15-28(-30) cm long, compound and oppositely pinnate with 5-9 leaflets, (5-)7-11 cm long, 2-5 cm wide, upper surface dull green, glabrous, lower surface pale green, puberulent along midrib, margins irregularly serrulate, apex long-acuminate, base cuneate, petioles 6-10 cm long, petiolules 3-13 mm long. Flowers are unisexual (and the plants dioecious), in panicles 13-20 cm long; buds paired, covered with brown, finely pubescent scales; calyx minute, 4-toothed. Samaras are oblong-elliptic to oblong-oblanceolate, 2-4 cm long, the wing 5-6 mm wide, apex with a small notch. F. uhdei is sometimes referred to as an evergreen species but it is winter-deciduous in some regions.
