Environment : Notes about your surroundings.

Welcome rain: The hills are green, thanks to healthy seasonal rain totals that were boosted by last week’s chilly storm.

“You could say we’re definitely in the full swing of the rainy season,” said Mike Evans, owner of the Tree of Life Nursery in San Juan Capistrano, which specializes in native plants. So far this season, Evans has measured 7.75 inches of rain at the nursery, which he called “pretty good for this time of year.”

The rain means plenty of green, vigorous growth in the county’s hills and canyons. The damp soil also makes conditions ideal for wild mushrooms. The recent storm did bring some bad news for the local vegetation, specifically the laurel sumac; low temperatures can “burn” the plant’s leaves. “Some of it did burn during the last frost,” Evans said.

Mistletoe: At odds with its romantic association with the holidays is mistletoe’s true nature: It’s a parasitic plant that takes its nourishment from trees. Only in rare cases does it kill the host tree--that would be an unfortunate development for the tree and the mistletoe that depends on it.

Locally, mistletoe grows in sycamore trees. The plant, which is green all year, becomes more conspicuous as the trees lose their leaves--and that tends to happen just in time for the holiday season.

“A lot of people don’t know we have mistletoe in Southern California,” said Nancy Bruland, president of the Orange County Trees Society and a park ranger at O’Neill Regional Park in Trabuco Canyon. When park visitors spot mistletoe, they often want to have some, either to decorate their own homes or to sell.

“Everybody wants to collect it,” Bruland said, and that can be an enforcement problem: “Everything’s protected in the parks, even the parasites.”

Bruland added that this year has brought a healthy harvest of acorns from the native oaks trees, which is good news for the animals that depend on acorns for nourishment. “They’re real important as a food source for all kinds of wildlife,” said the ranger, who in recent days has watched acorn woodpeckers harvest acorns from the trees.

Acorns usually begin to fall in October, and the harvest is now coming to a close. Most acorns ends up as meals; just a few acorns survive until spring and germinate.