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Mysterious white lilacs special to South Laguna

April 15, 2005

ELISABETH M. BROWN

It was April ten years ago, while driving along PCH near the Lucky's,

now Albertson's, shopping center, when I first noticed them -- large

dark green shrubs covered with white flowers on the South Laguna

hillsides. They were very showy, and I wondered about them because no

other part of the Greenbelt sported white flowering shrubs at that

time of year. In my typical coastal sage scrub neighborhood of Canyon

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Acres, the slopes were sprinkled with yellow from the flowers of the

bush sunflowers.

So I turned off and found my way to the closest of the bushes. The

leaves and everything else about the mysterious plant indicated that

it was one of the large group of California lilacs, or Ceanothus.

Particularly intriguing was the color of the flowers: white instead

of the more typical lilac blue.

Biologist Karlin Marsh's survey of South Laguna confirmed that

there are two kinds of native lilacs in South Laguna.

For the botanically challenged, this might not be earthshaking,

but it tells us something significant. California lilacs don't grow

in coastal sage scrub, the dominant plant community in the Laguna

Greenbelt. Although there are shrubs with white flowers elsewhere in

the Greenbelt, they're very different plants, and they don't bloom at

this time of year.

To find the typical plant community where California lilacs grow,

you have to go inland and to higher elevations, like the Santa Ana

Mountains or Riverside County. If you're driving to the desert for

spring wildflowers this month, you start to see a few bushes with

blue flowers along Highway 91 in Santa Ana Canyon, and later they

show up as you climb towards Cajon Pass on Highway 15. There, the

roadside plant community is chaparral, another scrub community, but

quite unlike our coastal sage.

So why are those lilacs growing in South Laguna? They tell us that

something is different about the hillsides there.

Vegetation in South Laguna lives under conditions that are quite

unlike the rest of Laguna. For starters, the bedrock is not our usual

pale yellow sandstone, but a darker, harder, grey rock full of chunks

of other rocks, called San Onofre Breccia (pronounced brech-ia). When

it weathers to small particles it helps produce a soil with special

characteristics. The unusual soil and a special local climate that

includes winds bearing seeds from six different directions, plus the

influence of coastal fog, yield a unique and very rare mixture of

coastal sage scrub, inland chaparral (where the lilacs come from) and

coastal Baja plants. This southern maritime chaparral community

exists nowhere else in Orange County and is one of the rarest natural

communities in California.

Now is about the right time to look up at the South Laguna

hillsides and savor the sight of those white lilacs. Afterwards,

explore Laguna

Coast Wilderness Park and make your own discoveries. In matters

botanical, as in so much of life, "Vive la difference!"

* ELISABETH M. BROWN is a biologist and the president of Laguna

Greenbelt Inc.

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