Mission Manzanita

Mission manzanita (Xylococcus bicolor) is a close relative of the true manzanitas. Currently, it is restricted to small populations in southern California and northern Baja California, but it is thought to be a very old species, a relict of a species with a much broader distribution. Currently, our populations do not seem to be producing young individuals, a fact that is of concern to plant ecologists.

The pinkish-white, bell-shaped flower may have a small hole in the side, a robber hole, usually made by a bee, wasp or ant. Because the insect is too large, or otherwise disinclined, to enter the flower through the opening, it drills or cuts a lateral hole which allows it to access the nectar. This approach usually fails to pollinate the flower, and the insect gets something for nothing – hence the name “robber”.

Description ^2,59,290,315

Mission manzanita is a much branched, upright shrub with one or several trunks from an underground burl. Although it is generally reported to be less than 10 feet (3 m) in height at least one 20-foot (6m) specimen has been reported from Peñasquitos Canyon,³¹⁵ where it grows from a burl over 5 feet (1.5 m) in diameter and is estimated to be over 100 years old. The smaller branches have rough gray bark that sheds as they age, leaving smooth, reddish trunks, similar to trunks of true manzanitas The leathery leaves are elliptic to oblong, 1 to 2.5 inches (2.5 – 6.5 cm) long, from short petioles. Margins are smooth and are rolled under. Leaves are smooth and green on top; the underside is loosely covered with soft hairs, which give the lower surface a pale hue. Leaves may be opposite or alternate.

The flowers also resemble those of true manzanita. They are urn- or bell-shaped,  approximately 3/8 inch (0.9 cm) long and hang upside-down in clusters at the ends of the smaller branches. Clusters usually have less than 2 dozen flowers that tend to open at different times. There are five (or four) dark pink sepals, united at their bases, with broad, overlapping lobes. Five (or four) white to pink petals are united into a bell shape with a narrow mouth with overlapping, greenish lobes, which flare outward. There are generally ten stamens (our plants often have five), completely retained within the corolla. The lower half of the filaments have long hairs.  Anthers release their pollen through small, terminal slits. The single ovary is superior, with one cylindrical style and a green, minutely lobed stigma, which barely extends beyond the corolla. The style turns reddish brown and persists on the developing fruit after the petals have fallen. Flowers occur December – March.¹

The shiny red to black fruit are about 1/4 ” (5-8 mm) wide and resemble berries. Technically they are “drupes” with a thin exterior fleshy layer enclosing a very hard-walled seed chamber that contains up to five seeds. Fruit may persist on a plant through the summer.

Classification ^2,44,143

Mission manzanita belongs to the heather or heath family (Ericaceae). This is a large, diverse family, primarily found in temperate climates, often in poor soils. There are usually five sepals, united at the base, and five petals fused into a flower tube; there are usually the same number of stamens, or twice as many. Familiar members of the heather family include cranberries, blueberries, azaleas and the tall, stately madrones of north coast forests.

There are two other members of the heather family in the Reserve,⁴⁸ both of which are on the threatened or endangered list of the California Native Plant Society: summer holly (Camarostaphylis diversifolia ssp. diversifolia) and Del Mar manzanita (Arctostaphylos glandulosa ssp. crassifolia).⁴⁵

Mission manzanita resembles true manzanitas and was originally placed in the same genus (Arctostaphylos) but was reclassified into a one species genus, Xylococcus. The two are distinguished by small differences in the structures of flowers and fruits. A useful field distinction is the rolled under leaf margins of mission manzanita; the leaves of true manzanitas are generally flat.²

Ecology  

Like other plants in the manzanita complex, the narrow mouth of the flower restricts access to pollinators that are small enough to enter the flower opening or have long mouth parts that can reach the nectar at the flower base. These include small native bees and flies, and butterflies and hummingbirds.⁵⁹ A few bees, including bumble bees, collect pollen by “buzz-pollination”. They hang at the flower opening and vibrate their flight muscles, thereby shaking pollen down on themselves from the anthers inside the flower. ^41,59,314

In spite of successful fruit production, there is growing concern that our local mission manzanitas are not reproducing.³¹⁵ They can readily resprout after fires, but some sexual reproduction is necessary to promote genetic variability and to replace plants that are lost. At first, it was thought that the seeds lacked some stimulus to sprouting, perhaps something that operated in the past but is no longer present (such as passing through the gut of a grizzly bear). More recently, seedlings have been found, but their survival is poor. Concern continues that the last stands of mission manzanitas, the “queen of the elfin forest”³¹⁵ may be slowly dying out.

Human Uses  

There are numerous accounts of native Americans using manzanita berries for food or drink,^75,282 or for medicinal purposes.²⁹³ However, the precise species of manzanita is often not mentioned. Because of the limited range of mission manzanita, only a few local Indian tribes encountered it on a regular basis. The local Kumeyaay soaked the ripe berries and used this for a cool drink. “Put in water jar so that evaporation cools the drink.”¹⁶ To the north, the Luiseño made a similar “cider-like” drink.¹⁷

Interesting Facts ^41,316

Should you be close to a blooming mission manzanita, look closely for a hole in the side of the flower. Mission manzanita, like many plants with odd-shaped or narrow-mouthed flowers, may be visited by nectar robbers. These are insects, often bees, wasps and ants, that bipass the usual entryway and cut a small hole or slit near the base of the flower which gives them direct access to the nectar. Often these nectar robbers are species that are too large to enter through the flower opening and lack the long mouth parts that allow them to reach the nectar from outside; but some insects use both strategies. Since the nectar robbers bipass the stamens and pistil and do not pollinate the flower, they receive something for nothing and are “robbing” the nectar.