An Anthocyanin-Free Variant of Darlingtonia californica:
Newly Discovered and Already Imperilled
Keywords: field studies: California (USA), Darlingtonia, pigmentation.
The family Sarraceniaceae contains three genera: Sarracenia, Heliamphora,
and Darlingtonia. The genus Sarracenia has an unsettled
taxonomy, but all authorities agree it contains at least eight species.
A number of subspecies, varieties, and forms have also been described.
Heliamphora has a naturally fragmented range and has responded
to this by evolving into several taxa. In contrast, even though Darlingtonia
grows in scattered montane wetlands throughout southwestern Oregon and
northern California, the genus has but a single species, and no significant
color variants have ever been discovered.
In the spring of 1997 I surveyed a Darlingtonia seep in the mountains
of north-central California. I had first visited the site in the autumn
of 1992 after I had learned of it from Hawkeye Rondeau, a naturalist and
intrepid seeker of carnivorous plants. This site is particularly interesting
because it is at the extreme southeast edge of the range of Darlingtonia.
The plants grow in a sloped clearing which is densely hidden on all sides
by alders. This clearing measures approximately 20 m ¥
45 m, and is habitat for a number of other wetland herbaceous genera including
Carex, Drosera, Mimulus, Juncus, Orobanche,
Platanthera, Solidago, and Veratrum. Prominent wetland
woody plants include Alnus incana subsp. tenuifolia, Leucothoe
davisiae, Pinus contorta subsp. murrayana, Rhamnus alnifolia,
and Vaccinium uliginosum subsp. occidentale. Sphagnum
does not occur at this location.
Since it was early in the season the plants were in flower. Darlingtonia
inflorescences are similar in plan to those of Sarracenia. Each
erect peduncle bears a single pendulous flower that has five large yellow
drooping sepals. The five translucent red petals are so closely pressed
to each other that together they form a protective chamber around the
anthers and gynoecium (see Schnell, 1976, figures 4.2 & 4.3). This
chamber may only be entered near the petal tips, apparently ensuring that
visiting insects will deposit pollen upon the stigma immediately upon
arrival. As my ramblings took me to a much smaller (11 m ¥
13 m) adjoining clearing of plants, I was greatly thrilled to find anthocyanin-free
Darlingtonia specimens. In this article I describe some of my observations
of what I will refer to as these "variant plants," as well as how you
may obtain seed of this variety. The precarious conservation status of
these variant plants is also discussed.
Anthocyanin is a pigment found in many plants and is the source of red
and pink coloration in plants in the Sarracenia family. Recent
work by Sheridan (1997) indicates that a single mutation can block the
production of this pigment in Sarracenia. A number of Sarracenia
mutants have been reported which lack anthocyanin (this is reviewed in
Sheridans work). On occasion Sarracenia plants have been
found which have abnormal flower colors but which are not completely anthocyanin-free
plants. At first I thought the variant Darlingtonia plants were
such floral mutants, but inspections of their growth crowns revealed a
complete absence of red pigmentation in the leaf shoot apexes and developing
pitchers. (A subsequent literature search revealed that the plants had
previously been noted by a field researcher who thought the plants were
merely yellow-flowered; Elder, 1994.) The variant nature of these plants
is clearly genetic and not environmental because of the following reasons.
1) Most of the variant plants were growing in full sun so the absence
of anthocyanin is not a response to inadequate light levels. Three variant
plants that did grow in shade exhibited the same pigmentation characteristics
as their sunlit companions.
2) No intermediate color forms were noted. This is parallels the behavior
of the anthocyanin mutation in the genus Sarracenia.
3) Variant plants grew interspersed with normal plants, so local factors
such as chemicals leaching through the soil could be eliminated. Furthermore,
the complete suppression of anthocyanin pigments by environmental effects
is unknown in Sarraceniaceae.
As the flowering season progressed I carefully surveyed the site using
binoculars (I avoided tromping through the seep because it is so delicate).
The variant plants occurred in nine separate loose associations, six of
which were in the smaller clearing. A total of 105 variant flowers were
observed. In comparison, by measuring the flower number density at various
locations (typical values were 11--18 flowers m-2) and extrapolating
over the area of the two clearings, I estimate that approximately 16,000
normal red flowers were produced this year. Even at this site---its only
known occurrence---the variant form represents less than 1% of all the
plants present. No doubt a few flowers eluded me, but I probably detected
all the major associations of flowering specimens. Surveys of nearby Darlingtonia
sites revealed no other variant plants. Since Darlingtonia plants
do not have much red coloration in their pitchers, late-season variant
plants do not look much different from normal specimens and any future
surveys for variant plants must be conducted during the flowering season.
Obtaining seed for distribution
Immediately after I discovered the variant plants I contacted the owners
of the property and obtained permission to pollinate the plants and collect
seed. I selected eleven variant flowers long before they matured and bagged
them with 1 mm mesh fabric. The stigmatic surfaces of unbagged plants
were usually slightly darker-colored a few weeks after their flowers matured.
This discoloration appeared on the bagged plants only after I manually
pollinated them. From this I conclude that I successfully excluded pollinators
and also that pollinators are present even at this site at the extreme
edge of the plants range. It is still unclear what pollinates Darlingtonia,
but my measures almost certainly frustrated the efforts of any pollinating
agents. Incidentally, nearly every unbagged Darlingtonia flower
in the clearings contained at least one spider (as has been previously
reported, i.e. Elder, 1994)---it must be challenging to be a Darlingtonia
I desired seed of pure anthocyanin-free strains for distribution among
scientists and horticulturists so I self-pollinated eight of the bagged
flowers. To ensure successful pollen transfer each flower was selfed both
28 May and 1 June. Unfortunately only four of these eight bagged flowers
survived to produce seed---shortly after pollination the other flowers
died from trauma associated with being handled. Years of experience in
Sarracenia propagation have shown me that the progeny of such selfings
are often not as vigorous as that from cross-pollinated plants. So I pollinated
three bagged plants using pollen from two other anthocyanin-free plants
(that is, pollen from both pollen donors were applied to each of the three
bagged plants). Darlingtonia can reproduce vegetatively, both by
rhizome division and by stolons. To minimize the chance that the pollen
donors were clonally related to the bagged plants, the pollen donors selected
were 8 and 11 m from the pollinated plants. Due to handling, only one
of these flowers survived to produce seed---Darlingtonia peduncles
are very brittle, especially when the scientist pollinating them is beset
by voracious mosquitoes and gathering lightning storms.
Seed was harvested in September and is available through the ICPS seedbank
(see the seedbank listing in this issue). This seed is not regulated by
C.I.T.E.S., so it may be bought by any member of the ICPS. To simplify
the seed distribution and to increase the chances that the most vigorous
seeds are widely distributed, the seed from the pollination trials were
mixed together. As a result three different mixes of seed are available.
Mix #1: The results of five manually pollinated variant flowers were
combined. Four of the flowers were self pollinated, one was crossed
with other variant flowers. These are very likely to be anthocyanin-free
Mix #2: Five unbagged variant flowers were allowed to be pollinated
by whatever natural mechanisms are at work in the seeps. If they are
selfed then the progeny will be anthocyanin-free. If they were crossed
they are very likely to be hybrids with normal flowers. In this case
they will probably appear to be normal red-flowered plants.
Mix #3: Seed from nine wild pollinated flowers were collected at the
end of the season. The plants are from a unique and wonderful location
but will probably produce normal red flowers. Experimenters may wish
to use these seeds as controls in studies of the plants from this site.
Seed quantities from this season are limited, but samples from all three
mixes are being sent courtesy of the ICPS to other seedbanks around the
world. As I write this, cooperative agreements have been arranged with
the following organizations (more are being developed): Australian Carnivorous
Plant Society (P.O. Box 391, St. Agnes, South Australia 5097), and Gesellschaft
für fleischfressende Pflanzen (Frank Gallep, Zweibrückenstr.
31, D-40625 Düsseldorf, Germany). This list of societies is not meant
to endorse or snub anyone---it merely represents an eclectic list of societies
with which I am familiar. Investigate the seedbanks of your local organizations
for possible additional listings.
If you obtain seed, bear in mind you are part of a scientific experiment.
I do not know if the plants will breed true. It would be valuable for
any growers to report their results to Carnivorous Plant Newsletter.
Conservation concerns and considerations
Field collecting being condoned by the International Carnivorous Plant
Society? This is scandalous!
No, not in this case. First, all access to the site was fully allowed
by the owners. Second, only seeds were collected, with the exception of
a single plant which was used for an herbarium specimen. Third, this situation
represents the first find of this plant and is a valid attempt at introducing
the plant into cultivation. Fourth, of the 105 variant flowers at the
site, only sixteen were manipulated, so the effects from interfering with
just one seasons flowers are probably insignificant (recall that
Darlingtonia is a perennial species).
The welfare of the plants is certainly being considered. Indeed, everyone
who knows the site has agreed to remain quiet about its location. These
measures are justified because plants and fruit of anthocyanin-free Sarracenia
rubra subsp. jonesii have been repeatedly poached from that
plants only known location, in spite of its being a preserve protected
and studied by The Nature Conservancy.
The immediate future for this site is precarious. Although it was stewarded
well by its owners for many years, when I contacted them they told me
they had sold it and the new owners intended to log the property. While
the timber value of the seep is minimal, the timber value of the surrounding
forest is high. I met with the new owners and their forester. Through
nonconfrontational discussions, I was able to educate the owners as to
the biological value of the seep. An interesting development occurred
several weeks later when the California Department of Forestry (CDF) was
reviewing the timber harvest plan for the site. News of this logging operation
reached the internet; the resulting deluge of faxes and mail to the CDF
was a huge surprise. The CDF consulted with a number of experts (including
representatives from the ICPS) and ultimately the property owners volunteered
not to log within 100 feet of the seep, so the chances of disturbing the
water flow or accidentally felling a tree into the seep were diminished.
At the time of this writing, the site is once again for sale. The Redbud
Chapter of the California Native Plant Society (CNPS) is attempting to
cobble together enough money to purchase the site. Bound by National Forest
on three sides, including the uphill side, this site is excellently situated
to be a well-protected preserve. The present owners have agreed to make
significant donations to expedite the process, and The Nature Conservancy
has contributed a large matching funds grant. Only $8000 remains to be
raised in order to make this 10 acre preserve a reality. That might not
seem like much, but for these plants it is the difference between protection
and another episode of logging. If you wish to donate to this important
project, call Carolyn Chainey-Davis (CNPS, 916-273-1581) by April 1998.
While the International Carnivorous Plant Society played a significant
role in protecting this site through educating the land owners and advising
the CDF, it must take a back seat to the phase of purchasing the site
for protection. When we become a non-profit organization it might be possible
for us to be more active in this kind of project.
Directions for future study
If this site survives the next few years of logging and transitions,
it will be an interesting laboratory for the genetic study of anthocyanin-free
plants. If Sheridans work is correct and the production of anthocyanin
in Sarracenia may be modulated by a single mutation, it is plausible
that the trait in Darlingtonia is similarly recessive. Indeed,
no intermediate flowers were observed (i.e. flowers with pink or only
partly red flowers) so this seems likely. It would be interesting to investigate
the progeny of green ¥ red crosses (using
Sheridans red/green nomenclature). The results from red ¥
red or red selfings would also be interesting. It might be that many apparently
normal red plants are heterozygous and such pollinations work would
result in 25% green seedlings and 75% red seedlings.
By climbing 18 m up into a nearby conifer and photographing the seeps,
I produced crude overhead maps. These suggest the anthocyanin-free plants
occur preferentially (but not exclusively) at the edges of the seep. The
reality of these measurements must be investigated using careful statistical
Finally, as information regarding this interesting form accumulates it
may be appropriate to botanically describe the variant at the forma
level. If so, it will most certainly not be "Darlingtonia californica
f. heterophylla," so I do not want to see that invalid name thrown
around by growers!
Special thanks are due to the various owners of this special habitat
and their foresters for their foresight and generosity, to The Nature
Conservancy (California Regional Office) for useful information regarding
the history of the seep, to Carolyn Chainey-Davis of the California Native
Plant Society for her untiring efforts, and to Mandy Tu for her botanical
expertise and boundless enthusiasm.
Elder, C. L. 1994, Reproductive Biology of the California Pitcher Plant
(Darlingtonia californica), Fremontia, 22:4, p29--30.
Schnell, D. E. 1976, Carnivorous Plant of the United States and Canada,
John F. Blair (publisher), Winston-Salem, North Carolina.
Sheridan, P. 1997, Genetics of Sarracenia Leaf and Flower Color,
Carniv. Pl. Newslett., 26: 51--64.
Figure 1: Anthocyanin-free and normal Darlingtonia