Francis Marion National Forest, Part 2 — Locating the rare Sarracenia hybrid, S. Xrehderi — 2014-05-03

I mentioned in the previous blog entry that on Saturday, May 3, I met my Atlanta buddies, Alan Cressler and Steve Bowling in the Francis Marion National Forest near Charleston, South Carolina. The intended purpose for the trip was to locate and photograph a rare Pitcher Plant hybrid, Sarracenia Xrehderi. This hybrid is the result of cross-pollination between two Sarracenia species: S. rubra or Sweet Pitcher Plant and S. minor or Hooded Pitcher Plant. Over a very long period of time, the cross-pollination of the two species with their hybrids forms is what is called a hybrid swarm with the pitcher and flower morphology as well as the flower color being highly variable.

Here is a comparison of the pitchers of the two species with S. rubra on the top and S. minor on the bottom:

Note the white or translucent spots on the back side of the S. minor pitchers. We will come back to this feature later. This hybrid is considered rare, because the bloom time for the two species is usually separated by a week or more. This will obviously prevent the two species from cross-pollinating even though they share the same pollinator, a Bombus or Bumble Bee species. On very rare occasions, their bloom period will coincide, thus allowing for the possibility of hybrid creation.

Alan and I had come down to the FMNF late last year after the Pitcher Plants had already bloomed, so he wanted to be able to come back during the flowering season to photograph the wide range in flower color found in these hybrid plants. Unfortunately, the Forest Service had conducted a recent prescribed burn on adjacent savannah, and I suspect the fire got away from them, because much of the hybrid Pitcher Plant site had also been burned. There was evidence that the burn had been quite recent, since there were scorched pitchers and flower buds. The plants will most probably recover during the year, but they will not flower again until this time next year.

Botanical discussion here: Hybrid plants usually resemble both of their parents in many characteristics — especially the F1 or filial hybrids. F1 hybrids are first-generation hybrids or the first generation produced from the cross-pollination of separate and well-defined species. Once the hybridization process is allowed to continue — over many generations — the back-crosses may resemble one species more than the other.

The two species in question produce pitchers that are different in several respects. Sarracenia rubra has a 6-8 inch (15-20 cm) tall pitcher whereas the pitchers of Sarracenia minor may reach as tall as 20 inches (50 cm) in the FMNF. There is a significant difference in flower color: S. rubra produces a very dark red/maroon flower whereas the flower of S. minor is a bright greenish-yellow color.

Here is a side-by-side comparison of the two flower colors with S. rubra on the left and S. minor on the right:

Another difference between the two species is rather subtle, but it plays a very important part in identifying the hybrids, especially when the plants are no longer in bloom. Sarracenia minor has white spots or transparent “windows” on the back of its pitchers. Supposedly, this is to lure in the prey when it is perched under the hood on the pitcher’s lip. The interior of the pitcher is dark, but these transparent windows allow light to penetrate the darkness and motivate the insect to fly into the pitcher toward the light. When this happens, of course, it hits the back of the pitcher and falls down into the pitcher’s digestive juices. Sarracenia rubra does not have these transparent windows. However, the hybrid between these two species does have these windows. That’s how the hybrids can be differentiated from the species plants after blooming is finished. Any pitcher that has the morphology of or looks like it is a Sarracenia rubra but has these windows is surely a hybrid. Here is an image of the back of a pitcher that in all respects looks like a Sarracenia rubra, but the spots tell us otherwise:

Of course, it is quite easy to tell if a plant in the hybrid swarm is a hybrid when the plants are in bloom. Any flower that is not greenish-yellow or dark red/maroon will probably be from a hybrid plant. There is one exception to this rule: On very rare occasions, a Sarracenia rubra plant will have a bright, clear yellow flower. Many times, the flowers of the hybrid plants will have streaks or blotches of color. These plants are sought after by collectors. Fortunately, this hybrid swarm is not easy to locate, and so far, it has dodged the bullet of poaching…

The follow images will show you many of the different color patterns found in the flowers of this hybrid swarm. Keep in mind that the parent/species plants have either dark red/maroon or yellow-green flowers:

Finally, here is a shot of the rare, yellow-flowered Sarracenia rubra:

I was sorry that Alan and Steve did not get the full force of an area completely full of splashes of color as had appeared in previous years:

But, they did get a good taste of the variability of the color of the plants and flowers at this site. Perhaps next year bill be a banner year, once again, for these hybrid Pitcher Plants…

–Jim