Sonoma County’s oaks starting their showy spring display

A hovering froth of pale pink, chartreuse and pale glowing yellow is gracing our hillsides and valleys –– the soft luminescent color of our native oaks in new leaf and bloom.

We usually don’t think of our native oaks as showy in terms of color, but their spring leaves and flowers are living art and, right now, our green hills and soft-foliaged oaks create scenes worth seeking out.

This sensational illuminated landscape is created by the catkins and new leaves of California valley oaks (Quercus lobata) and black oaks (Quercus kelloggii).

Hillsides are suffused with a hazy, seemingly floating, impressionistic haze of pastel tones, and positively glow under gray skies or in the sun.

The long, dangling, delicate oak male flowers, called catkins, gradually elongate and release pollen, and as they do gain color, before they age to brown.

Oaks are wind-pollinated, and like many wind-pollinated plants, release a large amount of pollen in an effort for it to reach plants of the same species. At the same time oaks flower, new leaves emerge and unfurl in shades of the pink and the palest green.

Together the California black and valley oak leaves and flowers create a delicate haze of color for us to enjoy. Especially showy, the black oaks catkins and new leaves are often a radiant pink-red.

The leaf color changes from red-pink with glowing white leaf veins to pink, soft pale green, and finally as the new, sharply defined leaves mature- to a deep, shiny green.

Both new flowers and leaves are intensely colored and worth viewing closely.

In general, valley oaks leaf out and flower slightly later than the black oaks. New leaves and catkins are the softest chartreuse-yellow. Valley oaks can become giants in our valleys with wide sweeping, weeping branches.

They oldest trees are as much as 500 years old. When in flower, as new leaves emerge, a single tree with abundant branches is a sight to behold.

Oaks are monoecious, which means that male and female flower parts are present on each plant. Female flowers are held at the top of the long male catkins, and are few, small and nondescript.

Oaks are mostly self-incompatible- each tree cannot self-pollinate.

Flowers must receive pollen from distantly related or unrelated trees.

Some studies have shown that California valley oak pollen only travels about 300 feet, making highly isolated single trees less productive in number and viability of acorns.

When trees self-pollinate, the resulting acorns are fewer and have much lower viability, and offspring are less genetically diverse. A few species of native bees, such as those in the genus Hapropoda gather pollen from native oaks.

Kate Frey can be reached at katebfrey@gmail.com. Visit her website at freygardens.com. On Twitter @katebfrey