Although there were a few recent entries by me, they were written before I left for an ecology field course in California at the beginning of May. It was an amazing experience–I got to know some great people, saw a lot of the state and its diversity, gained a feel for what it would be like to be a field ecologist, learned a lot and enjoyed myself. It was a busy trip, though! We completed three observational field studies with write-ups and presentations in groups, had reading to do along the way with ensuing discussion and quizzes, went on tours and hikes, and of course had some fun tucked in between. Our route included traveling to the coastal redwoods, Lanphere Dunes, Bodega Bay Marine Laboratory, a quick afternoon stop in San Francisco, Hastings Natural History Reservation Biological Field Station in the Santa Lucia mountain range, Yosemite National Park, the Mojave Desert, a brief stop in Death Valley, and northward home along the eastern Sierra Nevada.
As part of the course, each student (there were 12 of us) was assigned a species we would encounter on the trip, be it a plant, animal, or insect and was to present on it when it was spotted. I chose manzanita, which refers to a group of evergreen shrubs or small trees within the genus Arctostaphylos. The word manzanita is derived from the Spanish for ‘apple’, manzana, with a literal translation being little apple.
Arctostaphylos is a genus within the Ericaceae, with habits ranging from prostrate to erect arborescent forms and heights spanning from 30cm to 6m. Some species have burls or woody platforms that will usually re-sprout after fire. Tree-like species often have distinctive smooth red bark that may peel over time. The leaves can be waxy and some have most of their stomata collected beneath the leaf–adapted for their drier habitats. The terminal inflorescences are collections of small pink to white-bell shaped hermaphroditic flowers in panicles or racemes. Most species flower in the spring, are insect-pollinated, and will develop pulpy berries in the autumn. The fruits either fall from the plant and germinate, or are dispersed longer distances by birds and mammals that feed on them.
Identifiable members of this genus date back to the middle Miocene, though it has been hypothesized that rapid diversification of species did not occur until the recent Pleistocene / Holocene epochs. It is thought that a variety of processes such as climate fluctuations, fire regimes, obligate seeder evolution, and hybridization between species have interacted to drive this genus’ radiation. The range of most species of Arctostaphylos stretches from British Columbia to Mexico, but a few species also have a circumboreal and north temperate alpine distribution, such as Arctostaphylos uva-ursi. There are 106 recognized species, with almost all of these growing in regions with a Mediterannean-like climate (cool-wet winters and hot-dry summers). Often, these Mediterranean-like species are limited to soil substrates with properties such as extreme pH, unique mineral content, high sand content, or extreme surface compaction. It is understandable then, that these Arctostaphylos species are themselves often rare or endangered.
Of the 106 species, about 96 species occur in California. The chaparral biome is considered their centre of diversity, with other Californian species occurring in oak woodland, savanna, and in transitional communities between chaparral and sage scrubland. The photo above is of Arctostaphylos nevadensis (pinemat manzanita) in Yosemite National Park, although Arctostaphylos patula (greanleaf manzanita, PDF) and Arctostaphylos viscida (sticky white-leaf manzanita, PDF) are also present in the region (for some reason I failed to photograph them–a feeling I have about much of the flora I encountered on the trip). Arctostaphylos columbiana, a species that readily hybridizes with others from the genus, was featured on Botany Photo of the Day in 2009. Other notable species in California include Arctostaphylos hookeri, a species that grows in serpentine soils. Notably, Arctostaphylos hookeri subsp. ravenii is an endangered species globally with a single individual remaining in 1987 near Presidio. It has since been successfully cloned and planted. Another species worth mentioning is Arctostaphylos franciscana, a species native to San Francisco that hadn’t been seen growing in the wild between 1947-2009, until it was spotted in the path of a highway renovation project and was transplanted. Many of the species are threatened due to habitat loss, degradation and fire suppression. There are ongoing conservation efforts for the rare and endemic species of manzanitas, looking at habitat preservation and recovery.
Members of this genus have ethnobotanical importance as well. Fruits of Arctostaphylos species have been used by many Native Americans for food–eaten fresh, dried, made into a drink, or added to mixtures of animal fat or fish eggs to make soup or porridge. Medicinally, the leaves, berries, or bark were used in the treatment of colds, kidney ailments, skin wounds, stomach pains, and blood diseases, as well as to prevent miscarriages. Some tribes also smoked the leaves to produce an intoxicating narcotic effect.