Very common on moist, lower valley slopes are large, evergreen shrubs or small trees with thick, dark-green leaves clustered at twig tips, to a Northerner's eyes looking like rhododendrons. However, the fruits -- which these days have just split open -- aren't like rhododendron fruits at all. I think the plants are TERNSTROEMIAS. You can see the unusual fruits below:
Those fruits need a bit of interpretation. Just right of center notice the star-shaped, cream-colored item. That's a flower's thickened, persistent calyx. The corolla withered and fell away long ago, and now the narrowly pear-shaped fruit has matured and split open. Upon splitting, a slender column remained in the fruit's center, surrounded by a few large seeds, each covered with a pulpy, red material (the aril). The seeds tumbled from their position but remained dangling from the column, attached by slender threads.
Mantle your seeds with a red, spongy, edible-looking material and set them dangling in free space... It's hard to think of a more effictive manner of offering seeds to potential disseminators such as birds.
Three Ternstroemia species are listed for the Reserve but I have no way of knowing which this is. However, most Ternstroemia fruits don't split open. One that does is an Asian invasive found in the US Deep South and other semitropical locations, so I'm wondering if our plants might not be that species, Ternstroemia gymnanthera. You can see one's opening fruits at http://oregonstate.edu/dept/ldplants/tegy10.htm
Ternstroemias are closely related to Camellias and the shrub producing leaves used as tea, the Tea plant. They're members of the Tea Family.