a new weed

This past win­ter I was notic­ing a weed pop­ping up all around the yard that I hadn’t noticed before. I was men­tion­ing it to John, and added, “I’m not sure what it is, though think it could be some sort of euphorbia.”

Then in the gen­tly tact­ful way spouses have of cor­rect­ing you and point­ing out your blind spots he qui­etly cleared his throat and pointed to one of the four young pot­ted plants we have around the gar­den of Euphor­bia lam­bii, one of my dry garden-adapted plants from the Canary Islands. “Maybe it’s that?”

Uh, like duh. What else would it be?

Last year was the first that these plants bloomed, and this spring they bloomed with a vengeance. Dur­ing sunny weather over the last few weeks I’ve heard lit­tle pop­ping noises from the direc­tion of the plants, and have come to the con­clu­sion that the sounds were that of seed pods explod­ing and jet­ti­son­ing the dust-like seed every­where.

I may come to regret the day I intro­duced these to the gar­den, which accord­ing to my records is March 9, 2008.

Speak­ing of weedy plants, here’s another sur­prise seedling from the gar­den, a lit­tle baby red foun­tain grass, one of three seedlings I noticed this year. In recent years the related green foun­tain grass, Pen­nise­tum setaceum has become a nox­ious (though stun­ningly beau­ti­ful) weed and has landed high on vir­tu­ally every thou-shalt-not-plant list issued for Cal­i­for­nia. But many peo­ple gave a by to this related red plant. It was often pushed as being ster­ile and inca­pable of repro­duc­ing by seed, a piece of mis­in­for­ma­tion even I relayed in this blog. (I’ve cor­rected that ear­lier oops in case any­one reads that ear­lier post.) As you can see here it can repro­duce by seed, though this form doesn’t spawn the same way reg­u­lar foun­tain grass does. Nor is it imme­di­ately the same mon­ster pest that feather grass (Nas­sella tenuis­sima) can be.

Pok­ing around the web I found an updated plant descrip­tion at San Mar­cos Grow­ers that includes some inter­est­ing back­ground on this plant:

Recent work in prepa­ra­tion for the grass sec­tions of the Flora of North Amer­ica, which will include nat­u­ral­ized and cul­ti­vated grasses, indi­cates that the name cho­sen for this plant will be Pen­nise­tum advena or per­haps P. x advena. Dr. Joseph K. Wipff, pre­vi­ously with Texas A&M and now a tur­f­grass breeder, wrote the sec­tion on Pen­nise­tum and has indi­cated that Red Foun­tain Grass is most likely a cross between P. setaceum and P. macrostachys (AKA ‘Bur­gundy Giant’). As a hybrid the name would most appro­pri­ately be Pen­nise­tum x advena ‘Rubrum’. The latin word advena means “newly arrived” or “stranger.”

So is it safe to plant this form of foun­tain grass? Here’s my think­ing: Hybrids between species are often ster­ile. (Think of mules, the off­spring of a horse and a don­key.) But every now and then some­thing hap­pens that allows the hybrid to repro­duce. Some­times the seedlings will be just as nearly ster­ile as the imme­di­ate par­ent, but other times a muta­tion could ren­der the seedling entirely fer­tile. In that lat­ter sce­nario the nearly-sterile foun­tain grass could turn into some­thing with the ugly inva­sive poten­tial of its Pen­nise­tum setaceum ancestor.

In other words, today I would be cau­tious and not plant it. Unfor­tu­nately, almost twenty years ago, we designed the front yard around a big mound of the stuff. The plants look stun­ning and move gra­ciously in response to the breezes. Their size is per­fect for the spot, and their red color is unmatched among other grasses. Every now and then I look at other options, like those rec­om­mended in the Don’t Plant a Pest brochure put out by the Cal­i­for­nia Inva­sive Plant Coun­cil. But these lists often fall short in the alter­na­tives they offer and end up read­ing like, “Cheese­cake is bad for you. Would you like to eat this deli­cious raw rutabaga instead?” So…I’m still look­ing for the per­fect replace­ment plant–hopefully some sort of native, but in the mean­time I’m pulling the occa­sional seedlings.

June 20 2010 | Categories: gardening • my garden | Tags: • • • • | 10 Comments »