Monthly Archives: November 2012

The Point Reyes Peninsula is geologically and geographically fascinating. It’s a chunk of high-riding land on the Pacific Plate, sandwiched up against the rest of Marin–and the continent–which is on the North American plate. Inch by inch, Point Reyes is creeping northward. The fault runs through the Bolinas Lagoon and created Tomales Bay. Stone and soil have entirely different provenances across the invisible line of the fault. The plants change across the fault as well–and one of the most dramatic of those changes is the abundance of bishop pine (Pinus muricata). This tree has an extremely limited range, and in Marin it mainly grows on Point Reyes, though scattered trees can be seen elsewhere.

Because of this the graceful pine is iconic of the peninsula–especially since the Vision wildfire burned through in 1995. One of the unique things about this tree is that its seeds can only sprout after being heated by fire, so in the last fifteen years a dense and lush forest of young bishop pine trees has grown up in the areas where the fire burned.

You can distinguish bishop pine from other species of Pinus because its needles come bundled in pairs of two.

Saplings with large, shiny, deeply creased leaves grow on an old logging road just north of Arcata. This is cascara (Frangula purshiana), another plant of Pacific Northwest affiliation, which can be either a shrub or a small tree up to 30 feet tall. Most of its beauty is in its smooth gray bark and shiny leaves. The spring clusters of greenish-yellow flowers are unobtrusive, but the fruits are also striking–small purplish-black berries that look similar to those of its cousin, coffeeberry.

Native tribes used cascara bark as a laxative, and settlers found it so effective that  in the late 1800s it became the base of a commercial pharmaceutical that was exported to the rest of the US and Europe. For a time it was so heavily harvested that it was almost exterminated from some areas–some say that it still hasn’t fully recovered. In fact, according to Wikipedia (which I hate to quote, but here goes) even in 1999 cascara made up more than 20% of the national laxative market in the U.S., with a total estimated value of $400 million and the bark alone being worth $100 million.

Potential collectors should beware–some reports say that if the bark is handled for long enough, the laxative effects can even pass through the skin! Eaten fresh, or in large quantities, cascara bark is toxic and can lead to severe diarrhea and vomiting. The berries are described as “edible but not incredible.”

Cascara grows from BC to Northern California. It stops short of the Bay Area, but it is found in Sonoma county where it’s been reported from Salt Point, Fort Ross and other places.

I’ve been visiting Seattle this week, a city where I spent my college years and first learned botany. It’s been a treat to revisit the landscape of the Pacific Northwest–including the plants. Some are old friends who I haven’t seen for years; others are common down in California as well.

Tall Oregon grape (Berberis aquifolium) is one that falls in the middle. This scrubby shrub of the forest understory is distinguished by glossy pointed leaflets that grow 5 to 9 in each sprig; in the fall some of them may turn red.

It’s a common sight in the Pacific Northwest. But though it technically grows across most of the west coast (including almost all counties in California, according to CalFlora) I have never seen it in the Bay Area. And Marin is one of the only counties in the state that does not have any records of this species at ALL–though its similar-looking cousin, dull Oregon grape, does grow here. (This species, B. nervosa, has 9 to 19 leaflets).

The purple berries are tart; some people make them into jelly or wine–generally mixed with other (sweeter) fruit. The inside layer of the bark is brilliant yellow and can be used to make a dye.