Fraxinus dipetala aka California Ash

Fraxinus dipetala, or California ash, belongs to the olive family, Oleaceae. Its native range runs from the southwestern United States into Baja California in Mexico. Kew places it within the temperate zone. It is not native to Britain or Ireland. This species grows as a large shrub or small tree. Virginia Tech gives its height as up to 20 feet [6.1 metres]. It generally has a single main stem. Its form places it at the smaller end of trees rather than among large shade trees.

The bark changes as the plant grows older. Young bark is smooth and has a grey-brown tone. Older bark forms shallow scales in a roughly rectangular pattern. The twigs are greenish brown and range from moderately thick to stout. Some are round, while others have four angles. Brown scales give the buds a rough look. Large, shield-shaped leaf scars mark the stems where leaves once grew. These stem and bark traits provide details to check when identifying the plant without flowers.

The leaves grow in opposite pairs along the stems. Each leaf is pinnate, with five to seven leaflets. A whole leaf measures four to six inches long. Each leaflet measures one to two inches long. The leaflet edges have sharp teeth. Their upper faces are glossy green, while the undersides look paler. The paired leaves and divided blades are useful features for identification. The contrast between the two leaf surfaces adds another detail to check. These features describe the species itself, rather than a named garden selection.

White flowers open in spring as the new leaves emerge. Each flower has two petals and measures about a quarter-inch across. The flowers hang in clusters three to five inches long. Winged fruits follow the flowers and mature in mid to late summer. Each fruit is a samara about one inch long. Its broad wing is straight and reaches nearly to the seed's base. The seed itself is flattened. The fruit tip may be notched or squared off. The spring flower clusters give this small tree ornamental interest. Its winged fruit offers a second clear feature later in the growing season.