[ Lost in the Landscape ]

…and some not so garden-worthy

You could prob­a­bly gather together six gar­den­ers and get six dif­fer­ent opin­ions of what would make a plant garden-worthy. But I sus­pect there might be some­what more agree­ment on cer­tain other plants that prob­a­bly shouldn’t be included in a gar­den. Here are some encoun­ters from Sunday’s trip to Tecolote Canyon that would fall eas­ily into most people’s less-than-desirable category.

I’ll have to admit to actu­ally lik­ing this plant to the right. Dur­ing the win­ter it drops its leaves and is an attrac­tive thicket of upright or sprawl­ing branches. This time of year it starts new growth that has this warm red-brown col­oration. It’ll flower soon, and then set some loose clus­ters of white berries. Pretty, yes, and native, and impor­tant to wildlife. But this is poi­son oak. Maybe not the best choice for small back­yard gardens…

Most of the rest of my list below is com­prised of exotic plants that have staked a claim for them­selves at the expense of the native species. Dif­fer­ent loca­tions have their own list of inva­sives, so what you see below is tai­lored to South­ern Cal­i­for­nia. Some of these plants could be good choices for other loca­tions. Oth­ers would be trou­ble almost any­where you grow them.

[ At this point I’d like to ded­i­cate the rest of this Fri­day the thir­teenth post to Out­of­doors, who last month devoted her Fri­day the thir­teenth post to inva­sive plant species. ]

I won’t go into too much detail about this trou­ble­some trio. Peo­ple have been work­ing hard to get the word out on pam­pas grass, green foun­tain grass, and ice­plant. The grasses, in par­tic­u­lar, can be gor­geous things in gar­dens, wav­ing in the breeze and lend­ing their dra­matic form to groups of softly mound­ing land­scape shrubs. You can see why peo­ple want to grow them. But are they garden-worthy in South­ern California?

All three of these quickly check out of people’s gar­dens and make for the wilds. I found both grasses and plenty of ice­plant escaped into the canyon, here on this hill­side and in other spots. So, as pretty as they can be–and I con­sider this drift of foun­tain grass in the sec­ond photo to be par­tic­u­larly poetic–these three would be bet­ter left in their native lands, or grown in cli­mates where the weather might limit their spread.

This is the first flower I saw this sea­son on the local plants of onion weed (Aspho­delus fis­tu­lo­sus). The first time I saw it I thought it was a wild­flower and wanted some for my gar­den. In full bloom the stalks of white flow­ers are an impres­sive sight. But they do spread like crazy. Not a good choice for the garden.

This com­bi­na­tion of plants looks as impres­sive as any plant­ing assem­bled by prac­ti­tion­ers of the New Peren­ni­als gar­den move­ment. But once again, the plants aren’t really wel­come addi­tions to the canyon. In the fore­ground is teasel (Dip­sacus sp.), a plant with excel­lent year-round archi­tec­tural struc­ture but hav­ing inva­sive ten­den­cies that are con­sid­ered “Mod­er­ate” by the Cal­i­for­nia Inva­sive Plant Coun­cil (Cal-IPC). Here it’s set against a back­ground of last season’s black mus­tard, a prob­lem in these parts since it was intro­duced by the Span­ish in the eigh­teenth cen­tury. The Cal-IPC only con­sid­ers the mustard’s rangi­ness to be of “Mod­er­ate” con­cern, but also states: “Pri­mar­ily a weed of dis­turbed sites, but can be locally a more sig­nif­i­cant prob­lem in wild­lands.” I’d say it’s a more sig­nif­i­cant pest locally.

Fen­nel can be attrac­tive in the herb gar­den, but like the rest of the inva­sives in this post, this is another plant that gets around. Its over­all unde­sir­able impacts are con­sid­ered “High” by the Cal-IPC. If I see fen­nel offered in the local nurs­eries it’s usu­ally the bronze col­ored strain. It’s less vig­or­ous, but all forms are con­sid­ered inva­sive. I do wish this were a bet­ter choice for gar­dens because it hosts swal­low­tail but­ter­flies, but at least there’s plenty of swal­low­tail food out in the local canyons. The but­ter­flies won’t starve. Okay, I’ll pass.

Say “Old Cal­i­for­nia” to any­one who’s lived in these parts for long, and this plant will prob­a­bly come to mind. The Brazil­ian Peru­vian pep­per tree forms a gor­geous tree with long, del­i­cate leaves that move any time there’s a breeze. But unfor­tu­nately the plants develop berries that the birds find irre­sistible. While the Cal-IPC con­sid­ers their threat to Cal­i­for­nia to be only “Lim­ited,” there are plants that would be bet­ter choices.

The Aus­tralian pep­per­mint wil­low (Ago­nis flex­u­osa), although not a native plant, is a good drought-tolerant sub­sti­tute that looks a bit like the pep­per tree but doesn’t share its inva­sive ten­den­cies. If you must have a del­i­cate weep­ing tree that says “Old Cal­i­for­nia” but don’t mind a lilt­ing Aus­tralian accent, this would be a bet­ter choice–and you can get vari­eties with either green or dra­matic black foliage. Or you could give up alto­gether on the colo­nial look and go in for any of the truly native trees. It doesn’t get any more “old Cal­i­for­nia” than that.

As I reread this post I’m struck that I’m prob­a­bly not doing a par­tic­u­larly good job of dis­cour­ag­ing peo­ple from grow­ing these plants. I keep going back to the beau­ti­ful redeem­ing qual­i­ties of these inva­sives, and I guess that’s why they con­tinue to be such a prob­lem. The mind tells you they might be bad news, but some­times it’s hard to say no.

With this last image I leave the plant king­dom and turn to another species that’s native to the local canyons. This one I think you’ll def­i­nitely agree you wouldn’t want around. I won’t assume that you like snakes any more than I do, so if you want to see the pic­ture you’ll have to click HERE.

Still, who among you doesn’t think baby ani­mals are just the cutest things? Now, every­body, say “awwwww”… This is a lit­tle baby south­ern Pacific rat­tler, prob­a­bly no longer than my fore­arm and too young to rat­tle. I’m deathly afraid of snakes but man­aged to fend off the fear to snap the pic­ture and watch the snake as it coiled itself defen­sively and make like a sidewinder, slid­ing back­wards into the grasses.

I have to respect these ani­mals since they do won­ders to keep down the rodent pop­u­la­tion. And they’re every bit as native as the poi­son oak I showed ear­lier. But after hav­ing had one of these in the back­yard fac­ing off against my cat, I’ve def­i­nitely decided this is another species that’s not garden-worthy, at least in my enclosed lit­tle space.

I admit it, I’m a wimp. Nature isn’t always con­ve­nient is it? But throw out the rat­tlesnakes and pam­pas grass and black mus­tard and fen­nels and you’re still left tens of thou­sands of cool and friendly selec­tions to invite into the garden.

March 13 2009 | Categories: gardening • landscape • landscape design • places • plant profiles | Tags: Agonis flexuosa • Asphodelus fistulosus • black mustard • Brassica nigra • Dipsacus fullonum • fennel • invasive plants • onion weed • pampas grass • pepper trees • peppermint willow • snakes • teasel | 4 Comments »

wild and out of control

All over town here in San Diego you see the black mus­tard plant, Bras­sica nigra, now approach­ing the end of its bloom­ing period.

The undu­lat­ing yel­low mounds of it doing its thing are a spec­tac­u­lar sight, so much so that Napa Val­ley, up north in the wine coun­try, has an annual Mus­tard Fes­ti­val that’s just come to its con­clu­sion. The fes­ti­val host the expected Napa wine and food offer­ings, and also hosts con­tests in pho­tog­ra­phy, art and cook­ing with mus­tard. In addi­tion to how the plant looks, it has an inter­est­ing his­tory, as told by Napa pio­neer Calvin Chester­field Grif­fith, quoted on the Mus­tard Festival’s site:

This is the story of our early Cal­i­for­nia when it was only a wilder­ness, with great quan­ti­ties of trees, beau­ti­ful plains, all kinds of wild ani­mals and birds; many, many Indi­ans, and no white men at all.

Father Serra had come from Spain to Mex­ico to spread the reli­gion of Jesus Christ, and hear­ing about this beau­ti­ful, vast coun­try to the north, decided to explore it. With a few faith­ful fol­low­ers and Indian guides, he trav­eled north through what is now our glo­ri­ous and loved Cal­i­for­nia. As he trav­eled he scat­tered to the right, and to the left, the mus­tard seeds which he had brought with him from Spain.

The fol­low­ing year, as they returned south they fol­lowed ‘a rib­bon of gold;’ and fol­low­ing that path again Father Serra estab­lished his ‘Rosary of Mis­sions,’ begin­ning in San Diego and end­ing in Sonoma.

It’s an appeal­ing, roman­tic story, but it also side­steps the fact that the mus­tard has invaded much of the West, and can be found in most of the United States. As a robust win­ter annual, it can out-compete most native plants, par­tic­u­larly in dis­turbed loca­tions, and form vir­tual mono­cul­tures that pre­vent other plants from get­ting a foothold. The pic­tures above were taken a few blocks from my house, in Tecolote Canyon. Because of abun­dant mois­ture ear­lier in the year, the plants were well over my head in spots, eas­ily seven feet tall.

To the left is a pic­ture of a part of the canyon where the mus­tard hasn’t taken over. It’s a good exam­ple of coastal sage scrub, rich in plantlife and alive with birds and insects. The white-flowering plant in the fore­ground is black sage, Salvia mel­lif­era, bloom­ing up a storm, with yel­low deer­weed (Lotus sco­par­ius) behind it. So what would I prefer–a rich eco­log­i­cal mix of plants that host a range of ani­mal life, or a showy burst of color that nour­ishes almost no ani­mal life and is about to dry out to a wild­fire magnet?

Alert on a new inva­sive: Cousin Jenny, a new Mas­ter Gar­dener in South Car­olina, alerted me to a new inva­sive plant, cogongrass, a plant that’s being listed as a treat even worse than the suf­fo­cat­ing kudzu. Here’s a link to a story in the Beau­fort Gazzette. Like the black mus­tard, it’s an attrac­tive plant, but it’s also seri­ous bad news.

More on weeds and inva­sives: I’ve been leaf­ing through Weeds of Cal­i­for­nia and Other West­ern States, by Joseph M. DiT­o­maso and Eve­lyn A. Healy. It’s a sump­tu­ous two-volume set, a coffee-table book of weeds if there ever was one, with 3000 images of the 750 evil species it lists. It also comes with a CD-ROM of the images in the book that can be used with­out roy­al­ties for edu­ca­tional purposes.

In addi­tion to the 750 nas­ties, there’s a table in the back with poten­tial future threats from plants that are just enter­ing the ecosys­tem. The book leans towards the tech­ni­cal side, but there’s a handy glos­sary and index. It took me 20 min­utes to fig­ure out that the annoy­ing grass com­ing up in spots around the yard was tall veld­grass. But with other species I was able to go right to the offender.

I found it strik­ing that a huge num­ber of the weeds–like the black mustard–were of Euro­pean ori­gin, likely brought over by set­tlers from there over the past cen­turies. Con­trols have since been erected that help reduce the entry into the coun­try of plants that might prove inva­sive. How­ever, with peo­ple, prod­ucts and pro­duce jet­ting all around the world these days, it’s inevitable that there will be waves of invad­ing plants from regions other than Europe. The cogongrass that’s of con­cern in the South, for instance, comes from Asia.

As I wan­der around the yard inven­to­ry­ing the plants com­ing up in the crevices, it’s weirdly com­fort­ing to know that my yard is con­tribut­ing to pre­serv­ing the earth’s bio­log­i­cal diversity–though unfor­tu­nately I’m not nec­es­sar­ily help­ing along the species that really need it the most!

May 03 2008 | Categories: landscape • plant profiles | Tags: black mustard • Brassica nigra • cogongrass • exotics • weeds | No Comments »