Evergreen Ash, Shamel Ash
Fairly fast-growing trees, most of which tolerate hot summers, cold winters, and many kinds of soil, including alkaline sorts. Chiefly used as street, shade, lawn, and patio shelter trees. In most cases, leaves are divided into leaflets. Male and female flowers (generally inconspicuous, in clusters) grow on separate trees in some species, on the same tree in others. In the latter case, flowers are often followed by clusters of single-seeded, winged fruit, often in such abundance that they can be a litter problem. When flowers are on separate trees, you’ll get fruit on a female tree only if a male tree grows nearby.
Ash trees are prone to borers. In some parts of California, ash whitefly is a problem; these chalky white, 1/8-in.-long insects colonize in patches on leaf undersides. Outbreaks are usually controlled by natural enemies; avoid spraying with broad-spectrum insecticides, which are likely to wipe out these beneficial predators.Fraxinus uhdei
Native to Mexico and a favorite in Southern California and low-elevation deserts. This evergreen to semievergreen tree grows fast to 25–30 ft. tall in 10 years; reaches 40 ft. in 20 years and may eventually attain 70–80 ft. or taller. Upright, narrow tree about 15 ft. wide when young; eventually takes on a spreading form as it grows older (may reach 60 ft. wide at maturity). Leaves are divided into five to nine glossy dark green, finely tooth-edged leaflets about 4 in. long. Foliage may burn if subjected to hot winds.
In the mildest climates, leaves hold on through winter; in colder areas, the tree loses most or all of its foliage, but the leafless period often lasts only for a short time. Sharp frosts may kill branch tips; tree will suffer serious damage at 15°F/–9°C or lower.
Grows to 2–5 ft. tall and 2–4 ft. wide. Long stems bear 3-in. flowers with dark blue cente...
South African native forms a clump 3–5 in. high, slowly spreading to 15–18 in. wide. Spiky...
Native to inland mountains and deserts of California into western Utah, Arizona, and northwest Mexico....