McLaren Park was once coastal scrub...

. . .very similar to the natural environment on San Bruno Mountain a few miles south.

The region was home to small bands of Ohlone and Miwok peoples. Around a century ago, small truck farms provided food for restaurants and markets, from root crops to fruit to eggs to geese. The park was dedicated by John McLaren in 1927. In the years after (as was the fashion at the time) Boy Scouts and WPA workers planted Monterey Cypress, Monterey Pine, Blue Gum Eucalyptus and other “exotic” trees around the park, which make up most of the forested areas we see today.

Most of San Francisco's remaining coastal prairies grow from a thin layer of soil atop radiolarian chert bedrock. Twin Peaks, Mount Davidson, Glen Canyon, McLaren Park, and Bayview Hill all contain fine examples of native plants growing atop chert bedrock. The native grasslands have incredible displays of wildflowers in the spring and early summer. The greatest threats to these sites are weeds and erosion. When trampling, erosion, or even burrowing animals disturbs the soil, the native plants are damaged or cleared away. Then the most aggressive plants (always invasive and nonnative plants) establish themselves.

-- from San Francisco: A Natural History
by Greg Gaar and Ryder W. Miller

Despite these decades of invasion by unchecked "weed" species from foreign climes, and numerous non-native plant species left over from the area's ranching and farming history -- from fruit trees to wild radish to wild fennel to patches of dense French broom -- dozens of native plant species still thrive here. Today, the emphasis is on preserving and enhancing the original features of the landscape, yet a diversity of habitats is also desired to support a wider variety of wildlife in our remaining open spaces.
  

Late season fruiting vegetation such as [non-native] Himalayan blackberry is an important source of food for resident and wintering birds within McLaren Park. Vegetation management activities that results in the removal of these plants can reduce habitat complexity and available food.
-- from Significant Natural Resource Area
Management Plan for McLaren Park

Some of the invaders have even found a beneficial niche. Anise Swallowtail butterflies have adopted to the invasive wild fennel. Non-native wild oats and rattlesnake grass provide abundant cover and feeding ground for flycatchers, swallows, and other small bug-eating songbirds, as well as hunting grounds for raptors. Some insect-eating birds feast on bugs attracted to flowering eucalyptus trees, even while the same trees are often considered weeds for the tendency towards monocultures in the soil around them.

Over time, I expect that the course will create a more open, less densely vegetated space. Young trees and shrubs will be absent from the "fairways." The course will be comprised of mature trees with a high canopy, but without an intermediate layer of small trees.
-- from Arborist's Report on Golden Gate Park disc golf course, 2005

All of this complex and interconnected ecosystem together is our natural heritage, of which less than five percent of San Francisco's remains. Yes, there are serious problems with invasive species in McLaren Park. But the installation of a disc golf course would not solve any of them, as any invaders removed from the course area would soon be replaced by an ever-thickening, ever-spreading "crust" of imported woodchips, reducing plant growth of any sort. Any proposal that would so diminish such a large area of our living history is simply unacceptable. 

Coastal redwoods
Fog is an important part of redwood ecology
Picture from Wikipedia Commons
[click photo for info]

Native trees

Arroyo Willows - The yellow, fuzzy spring-time blooms of this willow always attract the bumblebees.  Found along Gray Fox Creek, and along the path to the Upper Reservoir.

Coastal redwoods - There is an small secluded redwood grove between the Upper Reservoir and a picnic area on Shelley Drive to the north.

McLaren Park arroyo willows
SMP photo by Ed Brownson
[click photo for info]

Native grasses

It would be nearly impossible to overstate the ecological significance of purple needlegrass to the original or pre-Spanish Pacific Prairie.
-- from California Grasslands

Purple needlegrass was once food for elk, deer, and rabbit. The seeds were an important food source for many California Indian tribes. Today, it is the 'State Grass of California' and plays an important role in native grassland restoration and erosion control.

Arguably the most significant remaining native grasslands in the park, there are only five acres of purple needlegrass prairie remaining in McLaren Park, although small patches are found throughout McLaren's grasslands.

Native grasses are interesting characters. They can be amazingly old. Many bunches of purple needlegrass are at least 200 years old and some might live as long as 1,000 years. As one of the old Califorñios, they deserve our respect as tough survivors. Using roots that extend up to 18 feet, they tap into nutrients and water found deep in the soil, and so remain green even in the hot, dry months of fall.
-- from Landowners Guide to Native Grass Enhancement and Restoration by Hastings Natural History Reserve

Other native plants

Miner's Lettuce
SMP photo by Ken McGary
[click photo for info]

Coyote Brush - A popular habitat for a wide variety of song birds, found mostly in coastal and desert areas of California.  Only a few acres of coyote scrub remain in McLaren.

Miner's Lettuce - refers to its use by California gold rush miners who ate it to get their vitamin C to prevent scurvy. It can be eaten as a leaf vegetable, raw or cooked, and tastes similar to spinach.

Cow Parsnip - Perhaps the most common use was to make poultices to be applied to bruises or sores. In addition, the young stalks and leaf stems — before the plant reaches maturity — were widely used for food with the outer skin peeled off giving a sweetish flavor. The dried stems were also used as drinking straws for the old or infirm, and to make flutes for children. A yellow dye can be made from the roots, and an infusion of the flowers can be rubbed on the body to repel flies and mosquitoes.

Non-native grasses

Wild Oats - About 80 of the 165 acres of open space in McLaren Park are dominated by this annual grass.  It is not native to California, but has become naturalized and is now is found in every county of the state.

Rattlesnake Grass - Native to southern Europe, this annual grass is easily identified by it's snake-like grains, and is also known as quaking grass.