AYESHA RASCOE, HOST:
Deck them halls and do it, says Northwest Holly Growers Association, with domestically grown holly. An estimated 95% of the crop is grown in just two states - Oregon and Washington. Here's Deena Prichep on the holly's success and some concerns.
DEENA PRICHEP, BYLINE: The Holly Loop Trail at Portland's Hoyt Arboretum is certainly looking a lot like Christmas. It's full of all sorts of spiky green leaves and clusters of red berries.
MARTIN NICHOLSON: That's Ilex latifolia and then Ilex glabra, another species there.
PRICHEP: Martin Nicholson is a botanic specialist and arboretum curator. He points out varieties with white-tipped leaves, some with yellow berries.
NICHOLSON: There's so much variation. These leaves are so cool. Just massive.
PRICHEP: Nicholson's not the only one enjoying them.
(SOUNDBITE OF BIRDS CHIRPING)
NICHOLSON: The robins are in there at the moment, feeding.
PRICHEP: They're going to town.
NICHOLSON: They're really happy with this.
PRICHEP: It's not a real surprise that holly thrives here, particularly English holly, the classic green and red variety that's grown commercially. Ken Bajema is secretary treasurer of the Northwest Holly Growers Association.
KEN BAJEMA: The climate is very similar to places in England where it's the native tree. And it was brought by the English and German settlers to the West Coast.
PRICHEP: That was in the 1800s. Since then, it's taken off - and not just as a cash crop.
BAJEMA: Holly is probably one of the most widely planted ornamentals. I mean, I would probably say more than 50% of the residents in Portland have a holly tree in their yard.
PRICHEP: But some worry English holly has thrived a little too well. Andrew Gray is a research ecologist with the Forest Service's Pacific Northwest Research Station.
ANDREW GRAY: Some of the work from our inventory analysis indicates that the cover of holly has doubled in the last 10-year period, both in western Washington and western Oregon.
PRICHEP: And when English holly plants spread from runners that sprout from the roots or seeds dropped by birds, they take over, creating a sort of no-grow zone.
GRAY: They can basically turn into dense thickets, shading out, competing against other plants that might be more desirable or might have some natural role in a native forest.
PRICHEP: Now, to clarify, it's not taking over everywhere in the Pacific Northwest. Gray says although there are about 10,000 acres now dominated by these holly thickets, that's out of about 28 million acres of potential forestland. But whenever there is this sort of exponential growth, it's a concern, especially for a tough plant like holly.
GRAY: I've been engaged in my local parks, helping to remove holly. So I have firsthand knowledge of how difficult it is to get rid of.
PRICHEP: So do we have to cancel our boughs of holly? Well, probably not. Again, it's only the English holly that takes over. That's why the Hoyt Arboretum grows different varieties or hybrids that can't reproduce. Arboretum curator Martin Nicholson says when English holly does crop up along the trails and forests, like it does everywhere in the region, they root it out, sometimes with local volunteers. Luckily, it doesn't grow too fast.
NICHOLSON: When the plants are little and you see one, that's the time to pull it out and get it rid of it 'cause that's, you know, a five-minute job versus something that you might spend several hours on having a chainsaw.
PRICHEP: Nicholson says he's not coming for anybody's wreath. But if you do have a big English holly tree, he says consider digging it up and planning something else, maybe an American holly or Oregon grape.
NICHOLSON: There's some really good alternatives out there. And I think the more people who take them out and the less fruit there is available for the birds to feed on, then the less work we have to do in our natural areas to control it.
PRICHEP: And he points out those other plants can also make a nice Christmas wreath. For NPR News, I'm Deena Prichep in Portland, Ore.
(SOUNDBITE OF KS JAZZ ENSEMBLE, ET AL.'S "DECK THE HALLS (INSTRUMENTAL JAZZ VERSION)") Transcript provided by NPR, Copyright NPR.
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