Fraxinus americana white ash

American ash (Fraxinus americana) planted in the 1890s, Galvez Mall. Sairus Patel, 1 Nov 2022

Autumn Purple ash (Fraxinus americana Autumn Purple), our reliably earliest fall color, in the sunken garden behind Thornton Center. Chor Seng Tan, 19 Oct 2017

Pinnate leaves about 8–16 inches long with 7–9 leaflets, smooth green on top and pale underneath. The fruit is a hanging winged seed 1 or 2 inches long. A massive one stands west of Encina Commons off Galvez Mall, planted in the 1890s. A tall specimen is on Lasuen Street just north of Littlefield Center; another is in the dip on the west of that building among the gnarled buckeyes. You will see others in the vicinity if you prowl around the Arboretum long enough; their pure yellow leaves lighting up the brush. A magnificent pair is at 2332 Williams Street in Palo Alto. The girthy trunks of large specimens show the ridged diamond pattern similar to that of Modesto ash.

Autumn Purple ash

Autumn Purple ash on California Ave, Palo Alto. Sairus Patel, 18 Oct 2017

Autumn Purple (F. americana ‘Junginger’) is the trade name of a male selection that started to be used in Palo Alto in the early 2000s. Ours are not purple so much as golden with peachy orange-rose sections and a few russet highlights here and there. The crowns seem to glow from within, like embers. It is our earliest fall color, lighting up in October and going mostly bare by Halloween.

An impressive planting on campus is in the sunken garden at the old Terman Center location, behind Thornton Center. A couple of dozen flank the pathway down to the fountains from Thornton. The grouping on the right (as you descend the stairs) is almost twice the height and trunk width than the grouping on the left, perhaps because of differing soil compaction. Note the distinct graft line at the base of the trunks.

In Stanford Research Park nearby, a sidewalk allee of Autumn Purple ash fronts a row of coast redwoods (Sequoia sempervirens) on California Ave, at 2475 Hanover St. The sidewalk was built over Engineered Soil Mix, part of Palo Alto’s “structural soil” program. The trees’ thick roots snake across the soil’s surface. The delightfully perky winter profile of the canopy is almost a cartoon of a symmetrical, neatly branching tree, at least at this stage of their life.

Name derivation: Fraxinus – classical Latin name for ash; americana – American.