[ Lost in the Landscape ]

fun with hybrids

There are over a quar­ter mil­lion plant species known to biol­ogy. Of those more than 5,000 can be found in Cal­i­for­nia, and 1,500 in San Diego County alone. With so many amaz­ing plant species out there I still find myself being inter­est­ing in hybrids between the pure species.

My last post was on Sar­race­nia, the North Amer­i­can pitcher plants. The genus appears to be fairly new to the world in evo­lu­tion­ary terms, and all the species in the genus will hybridize eas­ily with any of the oth­ers. And all these hybrids will con­tinue to inter­breed with the par­ent species or other hybrids. When you find a bog with two or more species in it, chances are good that you’ll find inter­me­di­ate plants with traits of all the species present in that location.

This dri­ves biol­o­gists crazy. Find­ing a plant that’s a pure species can be a major headache when the plants are out there, frol­ick­ing in the mud. But evo­lu­tion­ary biol­ogy acknowl­edges that hybrids can intro­duce new genes into a plant’s gene pool so that they might be bet­ter equipped to with­stand some stres­sors that a pure species might not.

In addi­tion to pos­si­ble evo­lu­tion­ary advan­tages, a hybrid plant found in nature can be a really cool-looking mon­grel. And human-created hybrids that have been selected for spe­cific traits over gen­er­a­tions can begin to take a species or genus in direc­tions nature would never have imagined.

Here on the left is the Sar­race­nia hybrid Judith Hin­dle. I first encoun­tered mass tissue-cultured num­bers of it in the flower aisle at Trader Joe’s a cou­ple years ago. It’s a pretty great-looking plant by itself, but imag­ine a whole store dis­play of it. This human cre­ated selec­tion derives from three species, and its pedi­gree can be notated: ((Sar­race­nia pur­purea x S. flava) x S. leu­co­phylla) x ((S. pur­purea x S. flava) x S. leu­co­phylla).

Doing the math, you an see that it’s one-fourth S. pur­purea, this species. (My photo here isn’t the exact par­ent, just one gen­eral exam­ple of what this vari­able species can look like. Sev­eral tax­on­o­mists have decided that this plant I’ve shown you, S. pur­purea var. burkii, is actu­ally a new species, S. rosea, but it looks quite sim­i­lar and you can get the gen­eral idea…)

Another quar­ter of the ances­try comes from S. flava. (You might rec­og­nize this same photo from my last post. Once again this is just a rough esti­ma­tion of what the par­ent looked like. It’s actual great-grandparents were S. flava var. rugelli, a plant with pure green pitch­ers with a red patch in the throat.)

And the final two quar­ters of its ances­try comes from the gor­geous S. leu­co­phylla, the white-topped pitcher plant. I find myself com­par­ing the hybrid with the par­ents, try­ing to see the char­ac­ter­is­tics that came through in the final hybrid. Clearly S. leu­co­phylla has the most influ­ence in this cross.

Here’s another com­mon sar­race­nia, S. Dixie Lace. Larry Mel­lichamp, its breeder, isn’t 100% cer­tain of its parent­age, but he esti­mates it to be: (S. leu­co­phylla x S. rubra) x (S. psittacina x S. pur­purea). It shares two par­ents with Judith Hin­dle above, but intro­duces two new species into the mix.

The pres­ence of this ances­tor, S. rubra, is sub­tle, and is prob­a­bly most man­i­fested in the some­what upright-growing pitch­ers and the robust growth habit. (Once again, the plant I’ve shown is only a close approx­i­ma­tion of the S. rubra var. wher­ryi that was used for the actual cross. And yet again, this lat­ter species has been clas­si­fied as a sep­a­rate species by some taxonomists.)

The final ances­tor is S. psittacina, a plant that’s prac­ti­cally impos­si­ble to hide the pres­ence of in any hybrid. The lean­ing growth habit and pat­tern­ing of the pitch­ers takes sev­eral gen­er­a­tions to fade into the background.

Hybrids can hap­pen any­where. In the irri­gated part of my gar­den I have a few sage species from Europe and the Amer­i­cas. These are the leaves of Salvia sagit­tata, the arrow-leaved sage, a plant from Ecuador.

Next to it I noticed a young plant which at first I thought was a seedling of the of its neigh­bor. It has the same light green col­oration and coarse leaf tex­ture as does S. sagit­tata. When I started look­ing closer at the leaves, how­ever, some­thing seemed a lit­tle off. Instead of the dis­tinct arrow shape, the leaves are closer to oval. Seedlings some­times take a while to develop their mature char­ac­ter­is­tics, but I started think­ing that it might be a hybrid of S. sagit­tata with one of the other sages nearby.

Three feet away is S. nemorosa. It also has coarse-textured leaves, but they’re smaller, darker green and rounder (prob­a­bly “lin­ear” to “oblong” with a “cor­date” leaf base, accord­ing to the leaf mor­phol­ogy charts).

And about six feet away are sev­eral plants of the pop­u­lar ‘Hot Lips’ cul­ti­var of S. micro­phylla, a species from Texas into Mex­ico. Its leaves are smooth, much smaller, darker green and also more rounded. (I guess I’d call it an “ovate” leaf form with an “obtuse” leaf tip.)

Who do you think might be the father? I’m lean­ing towards S. nemorosa.

The seedling sage found a clear­ing in the mid­dle of a lit­tle walk­way to ger­mi­nate. I’ll let the seedling bloom to see if it’s interesting–or if it’s even a hybrid at all. See­ing the flow­ers should help me bet­ter guess what its par­ents might be. If it’s worth keep­ing I’ll trans­plant it out of harm’s way. If it’s not, I’ll treat it as any other unwanted gar­den col­o­nizer. What­ever the case, it’ll be an inter­est­ing lit­tle experiment.

Topic for a future post: What’s bad about hybrids?

October 27 2009 | Categories: gardening • my garden | Tags: hybrids • sages • Salvia microphylla 'Hot Lips' • Salvia nemorosa • Salvia sagittata • sarracenia • Sarracenia flava • Sarracenia leucophylla • Sarracenia psittacina • Sarracenia purpurea • Sarracenia rubra | 4 Comments »