Secrets of the Oak Woodlands: Plants and Animals among California’s Oaks
by Kate Marianchild
Excerpts from the manzanita chapter
“Manzanita first appears in the fossil record about 37 million years ago in central California. About 1.5 million years ago it began diversifying and dispersing to places throughout the West and as far away as Guatemala and Eurasia. Not surprisingly, the central California coast is the world hub of manzanita diversity. With an extraordinary ability to adapt to unusual habitats, the sixty-two-odd Arctostaphylos species come in a bewildering array of shapes and sizes, from two-inch-high ground covers to tall shapely trees.
Common manzanita and big berry manzanita, the two species discussed here, fit the genus’s popular image of a treelike shrub with muscular red thighs and arms that twist outward and upward in elegant gnarled curves. The silky skin and sinuous contours of these limbs have collected many a human caress, and in summer the thin red bark curls away to reveal bright green undergarments. On most mature plants, lovely rivers of silvery deadwood run alongside living burgundy wood. In winter, white or pinkish flowers resembling tiny upside-down urns hang in clusters of ten to fifteen blossoms that later turn into red-brown berries.” (pp. 85-86)
Buzz pollination in middle C “Manzanitas, madrones, and other plants that bloom in winter have a special challenge:how to prevent their pollen from washing away in the rain. Manzanita flowers, which hang downward, solve this problem with fused waxy petals that act like little raincoats, sluicing water away from the inner parts of the flower and protecting the tube-like anthers that harbor pollen. In fact, the pollen grains are so carefully cloistered that they cannot escape their snug containers without the assistance of insects.
That assistance comes in the form of specialized native bees known as buzz pollinators, many of whom are bumblebees looking for a meal of pollen. Watch for a bumblebee landing upside down on a manzanita flower. You won’t be able to see this, but first it disengages its flight muscles from its wings so that it won’t zoom away during its next maneuver. It then vibrates its flight muscles faster and faster until they produce a buzzing sound that corresponds to the musical pitch we know as middle C. When middle C is reached, pollen grains explode from pores at the tips of the anthers onto the bee’s abdomen. With pollen sticking to its belly, the bumblebee re-connects its wings and flits over to another flower, inadvertently fertilizing the new flower by dusting its protruding stigma (female part) with pollen.” (pp. 88-89)