Several species of Lomatium (desert parsley) with yellow flowers are native to Washington state, often appearing as early spring wildflowers on rocky slopes and prairies. Common yellow-flowering species include Lomatium triternatum (nineleaf biscuitroot), Lomatium utriculatum (spring gold), and the rare Lomatium bradshawii. They are characterized by umbel clusters and often have finely divided, carrot-like leave
I found a tag on one of the trees, many on Arrowroot Loop.
Carpinus betulus 'Fastigiata' (Pyramidal European Hornbeam) is a durable, slow-growing deciduous tree, ideal for formal hedges, privacy screens, or street plantings. It starts narrow/columnar and matures to a 30–40 ft tall, 20–30 ft wide, oval-vase shape. Known for its smooth gray, fluted bark and yellow fall color, it thrives in full sun to part shade and is highly tolerant of urban pollution.
Acer palmatum 'Sango kaku', or Coral Bark Maple, is a deciduous, upright tree (20–25 ft tall, 10–15 ft wide) celebrated for brilliant coral-red winter bark, light green spring foliage, and yellow-gold fall color. It prefers moist, well-drained soil in part shade to full sun, growing at a slow-to-moderate rate.