Sarracenia L

The Genus

BOTANICAL NAME: Sarracenia L. Named after Dr. M. S. Sarrazin of Quebec, an early discoverer. Family Sarraceniaceae.

COMMON NAME: Pitcher plant. (More specific common names will be mentioned with each species.) RANGE: Generally, various species can be found in appropriate bogs, savannahs, and other wet places throughout eastern North America.

FLOWERING AND TRAP SEASONS: Flowering periods vary from March to June, depending on species and locale. Most pitchers die back over the winter, and new ones sprout with or soon after flowering.

DESCRIPTION. — Pitcher plants are all basically perennial rosettes of leaves modified into traps that arise from long rhizomes (underground stems) which have fibrous roots. The pitchers of various species range in height from 10 to 120 cm. The rhizomes often branch and have several growth crowns, so that an apparent clump of plants may really be a clone; that is, the plants may all be connected.

The oldest part of the rhizome is often dead. Two species regularly give rise also to flattened, moderately wide, elongate, leaflike structures that are probably modified petioles (leaf stems) and are known as phyl-lodia. These usually appear at the end of the growing season and are often referred to as "winter leaves," since they remain throughout dormancy. The phyllo-dia, which assume various shapes, can be helpful in determining species.

The prominent, often highly decorative trap leaves are tubular, appearing somewhat like elongated funnels or cornucopias. Located at the top is a lobe called a lid or hood. This is usually supported on a narrower column of varying prominence. The hood or lid may be reflected over the pitcher opening or may be, as it is in one species, vertical. The lid is immobile. Running down the axial seam (that which faces the center of the plant) of the pitcher leaf is another lobe which is flattened and winglike, its size and character varying with the species and growing conditions. This structure is known as an ala or wing. Pitchers may be colored from green to shades of red, yellow, or white. The pitchers assume two general habits according to species: either erect or nearly erect to totally decumbent.

The pitchers possess several interesting adaptations which serve to lure and entrap prey. The bright coloration of the pitcher and the secretions of nectar along the margins of the hood, the rolled lip opposite the column, and in some cases the free margin of the ala lure ground and flying prey to the pitcher opening. The inside of the lid is lined by stiff, downward-directed hairs, which encourage descent and discourage ascent. These hairs vary in size and effectiveness according to the species. Contrary to common belief, the lid does not snap down to close off the pitcher after the insect is caught. Its exact function is not totally clear, but it does, to a degree, prevent the contents of the pitcher from being diluted by rainwater in species where the

Fig. 3-1. Sarracenia oreophiia. An example of a pitcher plant with an erect habit.

Fig. 3-2. S. purpurea ssp. venosa. A common pitcher plant showing a decumbent habit.

Fig. 3-3. S. purpurea ssp. venosa. Notice the hood with dense, long, stiff hairs lining the inside and pointing downward.

Fig. 3-4. Longitudinal section of pitcher of S. purpurea ssp. venosa, showing four basic zones: the inner surface of the hood lined with stiff, downward-pointing hairs; a smooth waxy zone; a glandular and absorptive zone without cuticle; and a lower zone of intermeshing hairs.

Fig. 3-5. Comparison of phyllodia /A'winter leaves"). Smaller, sharply curved S. oreophiia at top; longer and straight S. flava below.

lid is actually reflected over the pitcher opening. The lid must have a different function in 5. purpurea, where it is vertical.

After having ventured to the brim of the pitcher mouth or the underside of the lid, the insect frequently overextends its footing and falls in. The interior of the upper one-third to one-half of the pitcher is lined with a smooth plant wax which impedes footing in most cases, and there is seldom enough room to begin flight. Deeper in the pitcher, waxy cuticle is absent, and the unwaxed surfaces are capable of absorbing digestive products. All species have a deeper, downward-directed intermesh of hairs which further helps prevent egress. There are digestive glands that may secrete protein-digesting enzymes and fluids of various kinds and concentrations. Those pitchers that do secrete enzymes have a small quantity of them in their fluids before entrapment occurs, and the concentration of enzymes tends to increase after initial digestion and absorption. The relative digestive efficiency of these fluids and enzymes from the plant and their possible concert with microbial activity is still being assessed. (See Chapter 1, pp. 2-3.)

The effectiveness of the trap varies according to habitus and species. All the erect traps are extremely efficient, often filling to the point that excess insects can freely walk or fly in or out. The widely flaring and reclining pitcher of S. purpurea seems less effective; in fact, it is theorized that this species actually drowns its victims.

The digestive mixtures of the pitcher are not universally effective. Various protozoa and insect larvae, for example, have adaptations to resist digestion, and in fact they breed in the pitcher. Actually, the contents of the pitcher comprises a complex little ecosystem of algae, fungi, bacteria, protozoa, other microbes, and various resistant insect larvae.

The flower structure of Sarracenia is generally the same for all species, the only variation being in size, odor, petal color, and some details of petal shape. The flowers appear in early spring, usually before or as new pitcher growth begins. The scapes are tall, to 70 cm in some species, and they support a single nodding flower. The unique floral structure serves to encourage cross-pollination, although experiments have shown that artificial self-pollination is quite successful in producing viable seeds. As the spherical flower bud approaches opening, the scape assumes the shape of a shepherd's hook, and the actinomorphic flower opens facing down. There is an unusual modification of the style in that the distal half is expanded, so that the whole looks like an opened, inverted umbrella and is commonly referred to as such. The umbrella has five points between which hang the pendulous, elongate petals, which are strap-shaped to obovate (rounded, but wider than long). At each umbrella point is a small, V-shaped cleft, at the lower point of which is located one very small stigmatic lobe. The rounded ovary at the base of the style and the numerous stamens are located inside a sort of floral compartment, at the top of which are the five sepals, three bracts, and the bases of the petals; the pendulous portions of the petals hang along the sides of the compartment like drapes, and beneath is the cupped, expanded umbrella. At the bases of the petals are nectar-secreting glands.

The insect pollinator, often a bee, is probably attracted by the color of the petals, the nectar, and the odor, and usually lands at the bases of the petals beneath the frequently reflexed sepals, where it circumnavigates the flower several times. It finally enters at the only visible narrow parting of the petal "curtains," over a point of the umbrella, and thereby brushes any pollen collected from previous flowers onto the stigma lobe. Inside the flower, pollen has been

shed from the overhanging stamens and has fallen to the floor of the cupped umbrella, where the bee may collect it, or it may collect it while investigating the stamens and nectar glands near the flower base. When the bee leaves the flower, it may not retrace its steps by passing over one of the umbrella tips and stigma lobes, since this offers poor footing prior to flight. Instead, the insect exits more often by pushing out one of the pendulous petals and flying from the wider umbrella edge between two points, thereby minimizing the chance of depositing newly collected pollen on the plant's own stigma.

After pollination and fertilization of the flower, the petals drop, and the flower frequently assumes a more nearly or totally erect position. The sepals and umbrella remain all season as the seed matures. Even if the flower has not been fertilized, the petals fall within two weeks of the flower's opening. In autumn, the brown, tubercular seedpods split at five seams and shed teardrop-shaped, 2 mm, light brown to pink-gray seeds. Dispersion is probably most often by gravity and water. The seeds require a period of stratification (damp winter chilling) before they will germinate. This characteristic effectively prevents the freezing of tender seedlings during the winter months.

GENERAL. — A bog or savannah of tall, golden-yellow S. flava or brilliant, white-topped S. leucophylla growing so thickly that one cannot walk without stepping over plants, is indeed an attractive and often startling

Fig. 3-6. Flower of Sarracenia flava, typical of the genus. One petal has been removed to disclose the umbrella, the stigma point, and the stamens.

Fig. 3-7. Umbrella of S. flava flower spread out to show points and stigma lobes.

sight. Equally interesting, on a "trot" through a northern sphagnum bog, is coming upon clumps of gaping pitcher mouths of S. purpurea, which are sometimes just above sphagnum level while the rest of the plant is nearly buried in live red-and-green moss. Pitcher plants are certainly our largest and among our most easily observed carnivorous plants, but unfortunately they are very susceptible to change in their habitat. Very few of the heavily populated, multi-acre stands described earlier in the century are still extant in the southeastern ranges. More often, one will find only scattered clusters or individuals, sometimes clutching the bank of a ditch that has drained a nearby savannah.

Drainage and fire prevention allow dryland plants to move in, and these then compete with Sarracenia. The natural late summer and fall fires of years past helped prevent such recolonization by clearing the site

Fig. 3-8. A dense stand of S. flava in Georgia.

Fig. 3-9. A multicrowned plant of S. flava. Note the short grass kept cropped by overgrazing cattle, which do not eat the pitcher plants.

of debris and competing plants while the underground stems of the pitcher plants were protected. Many field experiments have demonstrated the beneficial effects of regular fires in a bog or savannah. There is some indication that fire may also release minerals tied up in dry, dead pitcher leaves and dead insects so that rains may leach them into the soil.

Regarding the effects of the control of competitors, I recall a situation in Georgia where a landowner had fenced off a section of savannah in which he was grazing cattle. He noted that the "lilies" (S. flava) were increasing inside his fence where the cows were grazing, while outside, the plants were decreasing. His puzzlement was further compounded by the failure of a yearly firing of the pasture to control the pitcher plants. Actually, he was burning competing plants, and the cattle were devouring all the grasses, herbs, and young woody plants —in other words, weeding. His misguided attempts to eliminate the pitcher plants in order to grow a good stand of pasture grass actually maintained a virtual garden of Sarracenia.

As we indicated, many small animals are capable of bypassing a pitcher or even converting it to their own use. Small spiders, snails, slugs, and frogs may visit the lips of the pitcher openings in search of food or

Fig. 3-9. A multicrowned plant of S. flava. Note the short grass kept cropped by overgrazing cattle, which do not eat the pitcher plants.

prey. The occasional report of frog skeletons in pitcher contents indicates that circumvention is not always successful.

The larva of a fly (appropriately named Sarcopha-ga) resists digestive action by the secretion of antienzymes. It feeds on the debris and pupates in the depths of the pitchers, doing no harm at all. People tell of opening "lilies" to remove the maggot and using it as fishing bait.

Within some pitchers, an unusual grass-cutting wasp builds a condominium of incubators consisting of alternate layers of dry grass and egg compartments with paralyzed crickets for the larvae to feed upon when they hatch.

But the greatest real attack on pitchers comes from a small yellow-and-black moth, Exyra. There are three species, each attacking different groups of species of Sarracenia in different ranges. The adult moth is able to walk about freely on the slippery, waxy surface of the inner pitcher where it hides during the day. If disturbed, it will back down the pitcher still further. If removed, it will promptly flutter to another pitcher and seek a new hiding place. The female lays one egg per pitcher, and the larva wreaks havoc.

The larva often spins a dense web across the pitcher mouth, closing off any further trapping. Then it feeds on the inner layer of pitcher tissue, causing the dried, papery top to fall over and seal the pitcher off from rain and interference. The pitcher becomes a private feeding and rearing area. The brown, collapsed tops of the pitchers are telltale signs of infestation, and many bogs are severely afflicted. In very severe climates, the larva may leave a mature pitcher and winter over for several seasons in the dead remains of previous years' growth. In the spring, it enters at the apex of a newly developing pitcher before it opens and girdles the top.

Fig. 3-10. Pitcher of S. flava opened to show infestation by unusual, grass-cutting wasp Isodontia. Plugs of grass alternate with stunned insects for the larvae to feed on when the eggs hatch.

Fig. 3-11. Pitcher of 5. flava infested with larva of Exyra moth. The top has collapsed because the inner layers of the wall have been consumed.

Before it pupates, the larva cuts two holes in the lower portion of the pitcher: one above the accumulated waste frass, to be used for escape as an adult moth (moths do not have cutting mouth parts), and a lower hole for drainage in case some water seeps in during the wet winter season. But there is partial rebuttal by natural balances. Some birds have learned that the holes mean larval or pupal food within, and slash marks made by beaks indicate that many of these parasitic insects never reached adulthood.

Since many larvae of Exyra do overwinter in the fallen, brown pitchers of the previous year, fire is again helpful to the plant colony by burning old litter from the previous growing season and destroying the harmful insects. Indeed, the most infested stands of plants are frequently those protected from fire.

The whole field of associations between pitcher plants and all the components of their environment is a fascinating study with a great deal yet to be explored. I have never gone into the field without returning with some new perspective, question, or idea.

The Species

Sarracenia purpurea L.

BOTANICAL NAMES: Sarracenia purpurea ssp. purpurea Wherry; Sarracenia purpurea ssp. pupurea f. heterophylla (Eaton) Fernald; Sarracenia purpurea ssp. venosa Raf. These are three more or less recognized entities within the basic species.

COMMON NAMES: Northern pitcher plant, southern pitcher plant, sidesaddle plant, pitcher plant, huntsman's cap, frog's britches, dumbwatches. (The last is an interesting local term used in the New Jersey Pine Barrens, where the expanded style and sepals that remain after flowering were thought to look like open watches without hands, and therefore mute.) RANGE: The species has a wide distribution as far west as northeastern British Columbia, where it was recently found, and over a good part of the eastern third of the United States and Canada, with an unexplained skip area in middle eastern Georgia. FLOWERING SEASON: From as early as March in its far southern range to July or August in the north. TRAP SEASON: Traps tend to be evergreen unless unduly exposed.

DESCRIPTION. — The pitchers are curved and decumbent, measure to 45 cm, and widen very prominently toward the mouth. There is a large, often slightly undulate ala. The hood rises vertically and is lined by long, stiff hairs. The edges of the hood are quite undulate and have lateral wings. The color of the pitchers varies from bright yellow-green to dark purple and is most commonly a middle variation with strong red venation.

Flower petals, sepals, and flower bracts are mainly rose pink to dark red. (See exceptions below.) The flower has a moderate odor of mixed nature, both feline or musty on one hand, and sweet on the other. Some have compared it to that of green peaches or peach twigs. The sweet component is most easily detected early in the morning or in shaded plants, while the feline odor becomes predominant in bright sun or as the day progresses.

Since the species covers such a wide territory, it is logical that there should be some evolutionary variation on the periphery of the range. There is, and the variations have been variously interpreted as separate species, subspecies, forms, or of no real significance. The preponderance of evidence leads me to the following interpretations for the present: The plants of the northern extremity of the range should be designated S. purpurea ssp. purpurea, a noteworthy form being S. purpurea ssp. purpurea f. heterophylla; the southern plant should be designated S. purpurea ssp. venosa.

S. purpurea ssp. purpurea has narrower, longer pitchers, which are smooth and glabrous (hairless) on the exterior. The diameter of the hood when the wings are pinched together does not exceed the diameter of the pitcher. Venation is frequently present when plants are growing in full sunlight, and there may be a diffuse, coppery purple color to the upper pitcher. Wintering pitchers of the northern subspecies often turn deep maroon and become green again in the spring.

The form of the northern subspecies, S. purpurea ssp. purpurea f. heterophylla, is found in one county in

Fig. 3-12. Two pitchers of S. purpurea ssp. venosa growing on the surface of a pond in the New Jersey Pine Barrens.

Fig. 3-13. Flower of S. purpurea, typical of a red-flowered Sarracenia.

Fig. 3-12. Two pitchers of S. purpurea ssp. venosa growing on the surface of a pond in the New Jersey Pine Barrens.

Michigan and in some eastern Canadian bogs in limited numbers, even though it may tend to dominate in an individual bog. This plant is without any red pigment at all, the pitchers and flower parts being yellow to yellow-green. Intermediates or form hybrids are easily found in such bogs if the typical subspecies is also present.

The southern plant is designated S. purpurea ssp. venosa. The pitchers are wider and stockier and have more prominent, coarse, red venation, always a fine coat of wooly hair (more easily felt than seen) on the exterior, and much more expanded hood wings.

This seems to be the best classification consistent with a broad perspective of our present knowledge. The two major subspecies are widely separated at the extremities of their ranges, and they have important biological differences and distinctive adaptive features that cannot be ignored.

When plants of one extremity of the range are transplanted to the other, they generally retain their characteristic features, but in a relative way; there is a tendency for the transplant to come to resemble super ficially the native. Therefore, local soil, water, and climatic conditions do play some part in determining the plants' forms, but always within the governing genetic framework of any group of plants.

Where the ranges of the two subspecies merge in the New Jersey Pine Barrens, one can find both forms either in separate bogs or often side by side in the same bog. There are, of course, many interbred intermediates as well.

Parallel to these observations, the species is host to the larva of a harmless mosquito of the genus Wye-omyia, one species of mosquito reportedly inhabiting the pitcher fluid of the northern plant, and another species, that of the southern. It has been suggested that, where the two subspecies intermingle in the New

Fig. 3-14. Comparison of pitchers of S. purpurea ssp. venosa on the left, and ssp. purpurea on the right. Note that the latter is generally longer and narrower and has a smaller mouth and less expanded hood wings.

Fig. 3-15. S. purpurea ssp. purpurea /. heterophylla growing in an open Michigan bog. Note complete lack of red pigment.

Fig. 3-15. S. purpurea ssp. purpurea /. heterophylla growing in an open Michigan bog. Note complete lack of red pigment.

Jersey area, each species of mosquito is able to select and stay with its appropriate plant. However, these initial reports have recently been questioned.

GENERAL. — Looking at the pitcher of 5. purpurea, one would guess that, of all the pitcher plants, this one would be the least efficient. It apparently has the weakest enzyme secretions and depends heavily on bacterial action for the digestion of its prey, or so present evidence seems to indicate. It traps its prey by drowning it. Since the mouth of the pitcher is widely exposed to weather and flood, rainwater can easily dilute or overflow the contents of the pitcher. But these are relatively synthetic observations which are probably not pertinent in the end. When one sees large populations in good strong bogs and notes the wide area of distribution, one cannot help agreeing that in spite of its clumsy appearance the species has certainly adapted and flourished. We have to learn more about its adaptations.

The most luxuriant stands of S. purpurea are in the northern reaches, where there are frequently massive clusters of plants with multiple crowns a meter or more in diameter. The species is also seen growing in dense, floating mats on water at the edges of bog ponds and lakes and nearly all the way across slower, acid streams.

In the southeast, there is an incompletely studied race of the species with large, diffusely red to purple pitchers in sun or even in shade. The flower petals are a pale pink and tend to be sharply curved around the outside of the pale green umbrella, rather than pendulous.

The species is often found adapted to alkaline marl bogs around the Great Lakes, where the pitchers are more numerous, smaller, more brightly colored, and brittle.

Sarracenia flava L.

BOTANICAL NAME: Sarracenia flava L. COMMON NAMES: Yellow trumpet, trumpet, huntsman's horn, lily.

RANGE: The species is generally confined to the southeastern United States in an arc of the coastal plain from Virginia through the Florida panhandle into the Mobile Bay area, but it can be found in some relic bogs in the southeastern piedmont. It has been planted in, and has adapted to, outdoor bogs in Pennsylvania. There are claims of adaptation even farther north, but the year-to-year persistence and quality of the plantings is disputed.

FLOWERING SEASON: Mid-March in the south to mid-April and May in the Carolinas. TRAP SEASON: The pitchers brown and wither at frost. Straight phyllodia are produced in late summer and persist all winter.

DESCRIPTION. — S. flava has an erect, handsome pitcher which grows up to 90 cm. The pitcher has a wide, flaring mouth and a broad, nearly flat, well-formed lid with a prominent keel and a strong column with backward-reflexed margins. The ala is much reduced. This species has considerable polymorphism (vein and color variation), particularly in the Carolinas, with less elsewhere in its range.

There are four typical forms. The most common is pale green to bright yellow when growing in full sun, and there is a large maroon splotch on the inside of the column, from which red veins radiate locally. The next most common form has a bright to deep red color on the external surface of the lid and column, sometimes extending down the pitcher to the ground. Venation is moderate, and the maroon color spot is weak. A third variant is uniformly golden-yellow in full sunlight, with such coarse and prominent red venation all over that the surface has a pleated or reticulate appearance. Again, the interior column spot is weak. Finally, there are plants with no red pigment at all, the mature pitchers being uniformly pale green to yellow. All these basic forms can occur in the same stand, although one or the other frequently predominates, and hybrid intermediates are easily seen. These variants have not been clearly named and are under further study.

The flower is large, and the petals are strap-shaped and bright yellow. There is a very strong feline odor which is noticeable from some distance. The plant produces ensiform (straight) phyllodia in late summer, and these persist through the winter. This fact has not been generally noted in the literature.

GENERAL. — There are areas in Georgia where one can still see magnificent stands of the species—tall, bold, bright yellow pitchers filling a large savannah and melting to a vast golden blur when viewed from a distance. S. flava is especially susceptible to the predations of the many insect larvae previously mentioned, but deleterious effects on the species as a whole are not perceptible. Unfortunately, the species does not respond to attacks on its habitat with equal fortitude, and prime lots of 5. flava are rapidly disappearing, especially in the Carolinas, which were once a main stronghold. This point was illustrated not long ago when an experienced field botanist and I were in what is left of the Green Swamp of eastern North Carolina. We were to finish our walks that day by visiting a favorite location of his for Sarracenia. After parking the car and hopping the inevitable drainage ditch, we scoured the savannah for half an hour or so and did not see one pitcher plant of any species. He was standing with a look of bewilderment on his face, and when I came over to him he shook his head and commented, "Where've they all gone? You could always come here when you wanted to see Sarracenias

Fig. 3-16. Yellow, heavily veined form of S. flava. Note that the purple area of the throat is not diffuse but is a confluence of veins.

Fig. 3-17. Form of S. flava lacking any red pigment. Fig. 3-18. Intact flower of 5. flava.

Fig. 3-19. Typical form of S. flava. Note the purple pigment in the "throat" of the pitcher.

Fig. 3-20. Red-topped form of S. flava beside typical plants.

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