A Viburnum With Some Teeth

Viburnum dentatum

I’ve been bicycling to work on paths that are often separated from the road by a vegetated buffer that is 20 or 30 feet wide. Over the past three weeks I have noticed a flowering shrub with white corymbs and broadly ovate toothed leaves. The habit is a cluster of arched trunks. When the apical bud is broken off other buds along the branch send new branches straight up, giving rise to the common name for this viburnum, arrowwood.

The real name for this shrub is Viburnum dentatum. It is one of several viburnum species distributed through southern New England. This species seems to be especially common in the sandy plains of down-island Martha’s Vineyard. Indeed, at least one of the plant guides notes its preference for coastal areas. It likes well drained soils, but tolerates a wide variety of settings and established plants are somewhat drought tolerant. All these characteristics will help survive the rigors of the central plain of this island, which is so dry that it was never farmed until the advent of drilled wells and large parts of it have never been farmed at all.

Space filling arrowwood as landscape shrub.

As with many easy going shrubs, this one is popular as an ornamental. It suckers like crazy around the base, so it is a good space filler and is planted around parking lots where you want to hide the lot and to prevent users from cutting through where they are not supposed to. The fact that it has attractive blossoms and berries—blue-black drupes—is simply a bonus. It does not need much maintenance although you are advised to prune it after it flowers.

Viburnums (which are part of the Caprifoliaceae family) are part of a small group of woody plants that have leaves that are oppositely arranged. The other common ones are Acer (the maples), Fraxinus (the ashes), Cornus (the dogwoods), Aesculus (the horseschestnuts and buckeyes). People used an acronym as a mnemonic to remember them all: MADCap Horse.

V. dentatum berries

Viburnums have been plagued by the viburnum leaf beetle (Pyrrhalta viburni), which is native to Europe and Asia and was introduced to Ontario, Canada in 1947. It reached Maine in 1994 and soon became a major pest throughout the northeastern U.S. V. dentatum is actually one of the species that is highly susceptible to an attack and a specimen will be killed two or three years into an infestation. There is a boom and bust pattern to the beetle populations. In spite of efforts to save landscape shrubs with sprays and removal of the egg-infested twigs, the beetles reach a point where they have reduced the local populations of viburnums to such low numbers that the larvae begin to starve. In addition, the populations of the natural predators rise along with the beetle populations. Infestations last for a few years and then it is advisable to wait several years before replanting viburnums as ornamentals.

In a 2011 article in the Vineyard Gazette that was about beetle infestations in general, Tom Clark of the Polly Hill Arboretum was quoted thusly: ““When this insect [the viburnum leaf beetle] gets here, it’s more a matter of time than anything else, it’s going to do some serious damage.” In other words, there are a lot of arrowwood viburnums along the bike paths here because the beetle has not yet crossed the seven miles of open sea to get here. In 2004 the state extension service reported that the beetle had crossed the Massachusetts/New York border and was laying waste to the Great Barrington area in the Berkshires. In 2012 the statewide report from the extension was still listing it only as a problem in the Berkshire region and it was a diminishing one.

 

Red Versus White

Oak holding onto leaves.

This time of the year—late October—most of the deciduous trees have dropped their leaves. Prominent exceptions are members of the family Fagaceae, which includes the American beech (Fagus grandifolia) and all the oaks (Quercus). They hold on to their leaves through the winter, a phenomenon called “marcescence.” The oaks are among the more diverse genera in the northeastern forest. They are dominant species in the “oak-heath” and “oak-hickory” communities that cover the drier, warmer, south-facing slopes of temperate eastern forests. There are about 90 species in the U.S., and many of them are important economically, mostly for building interiors and for furniture, and more esoterically, for boat building.

The oaks are divided into five “sections.” The first has the same name as the genus, Quercus (synonyms Lepidobalanus and Leucobalanus), which is also referred to more colloquially as the “white oak group.” Another is the Lobatae (synonym Erythrobalanus), which is usually called the “red oak group.” There is another North American section, the Protobalanus, which includes the canyon live oak and its relatives in Mexico, and two Eurasian sections, the Mesobalanus, the Hungarian oak and its relatives, and the Cerris, the Turkey oak and its relatives.

The Quercus section is Holarctic; its species are distributed in both the Old and New World in the Northern Hemisphere, but the Erythrobalanus species are confined to the New World north of northern South America.

Red versus white oaks

The “white oak group” is distinguished from the “red oak group” by leaves with rounded lobes that lack a terminal bristle on each lobe. The acorns of the white oaks ripen in one year and tend to be sweet and quite edible. Red oak species have leaves with angular lobes and a small terminal bristle. Their acorns take 18 months to ripen, and they are full of tannins, which give them a bitter taste. Squirrels and birds that collect the red oak acorns will bury them and let the tannins leach out of them for weeks or months to make them more palatable.

Each group has an eponymous species that demonstrates the characteristics of the classification clearly. The white oak (Quercus alba) can get to be an enormous spreading tree when it grows in the open. The crown can be wider than the height of the tree, which can approach 85 feet. It tends grow taller in the forest, but is still a massive tree. It doesn’t begin to produce acorns until it is at least 20 years old, and after it reaches 50 years, it produces more every year.

Tyloses in white oak wood

The xylem cells of white oak have tyloses, obstructions that cause the lumber to be very water-tight. Consequently, white oak is used for boat building and the construction of barrels, notably those for storing wine and bourbon whiskey. Quarter-sawn white oak was the signature material of Mission-style furniture made by Gustav Stickley.

The northern red oak (Quercus rubra) is large tree, like the white oak, but it tends to be less massive and when grown in the open forms a narrow round-topped crown. While white oak bark is gray with irregular raised plates separated by narrow furrows, red oak bark is darker, with narrower ridges and broader furrows. The ridges of the northern red oak appear to have shiny stripes down the center.

Red oak acorns are larger than those of the white oak. The inside of the cupule that covers the nut is also fuzzy in red oaks and smooth in white oaks. The red oak acorns display epigeal dormancy; they have to be exposed to three months of temperature below 40°F before the germinate. They over-winter on the tree and fall during the following growing season.

Red oak is used for building, but the wood lacks the tyloses of the white oak, which makes it much more permeable. Most hardwood floors made of oak, however, are made from trees of the red oak group. Q. rubra is the highest quality wood in the group, but flooring sold as “red oak” may include pin oak (Q. palustris), black oak (Q. velutina), scarlet oak (Q. coccinea) and other “red oak” species.

Orchids: Not Difficult. Just Different

I was introduced to orchids and to orchid care when I became friends with Stanley Adderley. His father, Lincoln or ‘Linc’ as I remember him being called, worked at the New York Botanical Garden, but also had two greenhouses full of orchids that were attached to the back of their house in Beacon, N.Y. Stanley had to take care of the orchids the way farm kids have to take care of chickens or pigs. They had to be watered and fed in a particular way on a particular schedule. Stanley carried out these chores in a fairly desultory fashion; I never got the feeling that he was going to follow in his father’s career footsteps.

Orchid without flowers

I never had much of a clue has to what was going on. The Adderleys’ greenhouses were an exotic environment, especially in the winter, when the air in there was warm and thick with moisture and many of the tropical and Southern Hemisphere varieties were in flower. During the summer they removed the heavy plastic covering from one of the greenhouses, which I believe was mostly full of Cymbidium, which were large plants with long blade-like leaves. That was the only genus name that stuck with me down through the years after the Adderleys moved back to the Bahamas.

Gradually I became aware of the enormous diversity of the orchid family (Orchidaceae) and that they were not all tropical species. Lady-slippers, for example, are a large temperate zone orchid that—but for over-harvesting—would be relatively common in deciduous woodlands. When I moved to western Massachusetts in my late 20s I discovered that rattlesnake plantain (Goodyera pubescens) was both an orchid and quite common on the forest floor of the Mt. Toby Range north of Amherst. Orchids began to seem a bit less exotic.

Over the years I have kept a few house plants, but have moved so often that I have never accumulated much of collection and have steered clear of varieties that I perceived to be delicate, including orchids. So, a couple weeks ago when my friend and I found an orchid in the hallway of her apartment with a ‘Free’ sign leaning next to it, I had no idea how to care for the thing. The poor thing had apparently been discarded after it had finished flowering. The flower stem was still attached, but bare. Neither of us had any idea what kind of orchid it was.

A Phalaenopsis variety

Then I saw a picture of an orchid on Facebook. Another friend had picked it up at Wegmans grocery store because it was bright colored and it was a gloomy winter day. I recognized the leaves on it as quite similar to our hallway orphan. It seemed to be a Phalaenopsis or ‘moth orchid,’ a large and much-hybridized genus that was popular as a house plant. Some of the species have flowers that resemble a large moth in flight. They cost $35 in Wegmans.

Over the past couple of weeks the leaves have been turning yellow and falling off the orphan Phalaenopsis. I had no idea how much often to water it, let alone provide any additional care. A quick trip to the Internet provided an avalanche of orchid care websites. One of them put it pithily: “Orchid care isn’t difficult. It’s just different.”

A site called Beautiful Orchids summed up the watering situation boldly. There were three different watering schedules for various kinds of orchid: 1) Varieties to keep evenly moist (not soggy or wet) at all times:

Paphiopedilum, Miltonia, Cymbidium, Odontoglossum. 2) Varieties to keep evenly moist during active growth, allowed to dry out between waterings when not: Cattleya, Oncidium, Brassia, Dendrobium. 3) Varieties to keep nearly dry between waterings: Phalaenopsis, Vanda, Ascocenda.

Healthy orchid

The other question I had is “What do you do with the flower stem?” Apparently a healthy Phalaenopsis can flower a second time, so when it finishes its first set of flowers, you cut it back to the first node before the flowering portion of the stem and it will sprout a secondary stem. These will be fewer and smaller than the first set.

Our Phalaenopsis was not healthy. There are exactly two leaves left on it and one of them is yellowing. In this case you cut off the whole stem and give it some food (orchid food only; not just any plant food), although not more than once a month.

These are the basics. If this orphaned plant revives I guess I will have to read a little further.

Coping With Too Much Water

The earliest plants were aquatic and likely evolved from green algae in the Cambrian Period, but the modern aquatic plants are land plants that have returned to an aquatic environment. Plants had to acquire many features in order to live on land, including a protective sheath to prevent them from drying out and specialized tissues to carry water and nutrients from the roots and leaves to the rest of the plant.

The first land plants were mosses and liverworts.

Returning to the water meant in some case losing some of the features and specialized cell types that they had acquired for sub-aerial life, or at least redistributing those features. In addition, they had to further evolve, developing new cell types and new morphologies to survive in the relatively low oxygen and low carbon dioxide environment under water.

The most completely aquatic plants live entirely submerged below the waterline. These are the most altered from their terrestrial ancestors. Land plants evolved rigid cells to enable them to stand up above the ground’s surface. Submerged plants are held up by the water. They also lack the cuticle that enables land plants to retain water and all of the plants’ cells seem able to absorb water, nutrients, and dissolved gases from the enveloping water.

The highly dissected leaves of Eurasion milfoil, an invasive species in the U.S.

Many submerged plant species have high dissected leaves (having a lacey pattern) or they are long, narrow and undivided. Dissection maximizes the amount surface area exposed to the environment and is essentially the opposite of what is seen in plants adapted xeric environments (e.g. cactuses).

These plants also have air-filled internal cavities where gasses can be stored and serve as interior atmospheres.

There are two classes of emergent aquatic plants: those with leaves that float on the surface and those that hold their leaves above the surface.

The most familiar example of the first are the water lilies. Lily “pads” have choroloplasts and stomata only on the top side, where sunlight can be absorbed and gas exchange can take place. This surface also has a waxy cuticle to prevent excessive evaporation. The leaves often have air cavities that serve as flotation devices.

The fragrant water lily.

Water lilies are an example of rooted floating plants. The roots serve large as a anchors and absorb little nutrition from the pond muck.

The other type of floating plant has no connection to the bottom at all. Duckweed is probably the most familiar example. These tiny vascular plants are so small that they are often mistaken for algae. Like algae they often produce asexually, with new leaves budding around the margins of the original one.

Finally there are the aquatic plants that are rooted in the water or at least saturated soil, but nearly all of the plant is sub-aerial. Cattails and reeds are familiar examples. These plants may be even tougher than the average land plant, having very rigid structure in order to withstand the occasional pounding they get from high water and storms.

Cattails around a retention pond.

In a wetland that includes open water, you will observe a zonation of aquatic plants with fully emergent plants like cattails at the shoreline, emergent plants in the shallow off-shore region and submerged plants in deeper water. The succession is called the hydrosere.

Eventually the water becomes too deep to allow rooted plants to send leaves up to a depth with enough sunlight to sustain photosynthesis. In some lakes where exotic species have been introduced, clarification of the water column by filter-feeding organisms like zebra mussels has allowed submerged plants to grow in deeper water than was formerly possible. Generally submerged plants can grow in water up to 3 meters (~10 feet) deep.

If you mind jumps to a marine setting like the kelp forests of coastal California, remember that kelp and all “sea weeds” are algaes and not vascular plants per se, which are much less common in saline and brackish environments.

Getting It to Arrive on Time Like Santa

My Christmas cactus started blooming a few days before Christmas, which is a first. The poor plant has been neglected for years, in part because my cats, particularly one of them, attacked any and all house plants. A ficus tree was quickly destroyed 15 years ago, but the cactus managed to survive by being consigned to marginal areas like attics and basements in the winter and being put outside in the warmer months.

 

Member of the S. Buckleyi group

There is a family story that this particular cactus is cutting of a plant that lived in my great- grandparents house in Hartford, Connecticut. This may actually be true; they can be very long-lived and I certainly have no recollection of buying it in a store*. They are also popular because they don’t require very much maintenance to survive, although getting them to actually flower at Christmas can be a bit of work.

The so-called Christmas cactus is actually a member of Cactaceae, the cactus family. This is worth noting only because common names can be misleading. For example, the water lily is not a lily. But it is not a desert plant, which to some extent accounts for its more delicate appearance.  Like most cacti, it has no leaves, but instead relies on its green stems for photosynthesis. The stems are flattened into vaguely leaf-like segments joined together like links. The flowers emerge from the joints or the ends of the stems.

Native habitat of Schlumbergeri genus

The genus Schlumbergera is native to the coastal hills of southern Brazil where it lives in the forest either epiphytically (growing on other plants, as many tropical orchids do) or on exposed bedrock. Both of these habitats are relatively more subject to drying out than other places in a tropical forest, which accounts for this house plants tolerance for neglect.

There are six wild species, but two of them were hybridized in the 19^th century to produce the first of a series of cultivars that are widely sold today. A decline in popularity in the early 20th century led some of the 19th century cultivars to be lost.

S. truncata gives rise to a group of hybrids that have zygomorphic flowers (bilaterally symmetrical) that are borne above the stems and have yellow pollen. The flattened stems have distinct points on their distal ends.

S. russelliana hybrids are referred to as the S. Buckleyi group (after the horticulturist who made the first crosses); the flowers of this group are actinomorphic (radially symmetrical) and hang below the stems. The stem segments lack the spines found in the truncata group.

The S. truncata group has pointed stem segments

The S. truncata group cultivars generally flower earlier in the fall and are therefore often referred to as “Thanksgiving cactuses.” The S. Buckleyi group tends to flower in December and January and so is more often called a “Christmas cactus.”

In their native Southern Hemisphere they all flower in May. The reversal of the timing in the Northern Hemisphere is due to its being induced by the seasonal shortening of days and lengthening of nights. It is the manipulation of this sensitivity that is the key to getting your house plant to live up to its common name.

My Christmas cactus spent last winter in the basement and didn’t flower at all. In fact, by the time I cleared the cobwebs off of it in May most of it was dead and even the weeds that had sprung up in it during its sojourn outside the previous year had dried up. I gently pulled off the withered stems of the cactus until it was mostly a woody stump with a few green segments remaining and put it outside.

It lived on the back deck between May and October getting full sun only very briefly (probably less than two hours) for part of the summer. It generally received only strong indirect light, which turns out to be exactly what this forest plant prefers. It recovered remarkably, with each bole of its woody stump sending a a few new stems that grew six to eight inches in a season.

I brought it inside in October before the first hard frost and put it in a cool nook that received indirect light most of the day (it faces northeast). It wasn’t particularly dark at night however, because the street lights shown into the room, but there was no overhead indoor light to turn on. In order to induce flowering horticulturalists recommend that a cactus be kept in absolute darkness for 12 to 14 hours for at least eight days in a row sometime in the fall.

It is also recommended that the plant we kept in a relatively small pot in a mixture of potting soil and either sand or vermiculite so that it never stays soaked for very long. Some sources recommend letting the plant dry out a bit in order to induce flowering, but other seemingly more scientific references suggest that there is nothing to this.

At any rate, my Christmas cactus, which is one of the S. Buckleyi cultivars is sending out several pink flowers right now. That is, it isn’t covered with blooms, but only gamely going through the motions, which given the only incidental “care” it’s received is about what can be expected.

*More recently I have been told that it is a cutting from a very old plant owned by our next door neighbor H. Mortimer Brockway and therefore dates from the 1970s.

Plants as Decorative Idols

Making “corn dollies” is an ancient harvest custom that died out with the advent of modern mechanized harvesting methods in the 19th century and was brought back in modified form as part of the “folk revival” of the 1960s (which extended well beyond folk music and represented a democratization and continuation of the Arts & Crafts movement that began in the 19th century). Corn dollies are by weaving dried wheat plants into anthropomorphic forms. It is often repeated that the tradition is pagan and that the figures represent “harvest gods.” The staid Answers.com surprisingly refutes this commonplace notion, dismissing it as a “discredited ‘Frazerian’ theory of corn spirits and fertility.”

Sir James George Frazer

Sir James George Frazer (1854-1941) was a Scot who taught at Trinity College, Cambridge for decades and was essentially one of the inventors of cultural anthropology. His central work The Golden Bough (1890) is a classic of late Victorian academic literature, but according to Wikipedia, “His theories of totemism were superseded by Claude Lévi-Strauss and his vision of the annual sacrifice of the Year King has not been borne out by field studies.”

The Year King is generic term for a host of “life-death-rebirth” deities, with which Frazer apparently associated the corn dollies. Incidentally, in Europe all grains were once referred to collectively as “corn” and “doll” is ultimately derived from the word “idol.” Answers.com huffs that because of Frazer’s mistaken conclusion the woven figures have not been well studied.

Although they may not be well understood anthropologically, they are certainly popular as decorative objects from the late summer into the fall as grain crops are harvested. A search on the Internet using the words “corn dollies” yields an avalanche of “how-to” pages, leading the tyro through the process of making a corn dolly step-by-step with written instructions, diagrams, or both.

Suffolk corn dollies

Grain weaving is widespread throughout Europe and each region seems to have its traditional forms. I say “seems to” and “traditional” because it sometimes difficult to tease out how much of what is called “traditional” is really something that arose during the Romantic revival of supposedly pagan customs through the nineteenth century (and then again in the 1950s and early ‘60s), and how much has a real pedigree in the ancient past. It is easy to think of objects like “Christmas trees” and the “Easter bunny” that are somehow related to some distant pagan practice but whose meaning and form have most definitely drifted.

Karen Reams, writing at helium.com, recounts local traditions in England associated with the making of corn dollies. She calls the earth goddess “Ceres,” her Roman name, and of course the Romans colonized much of England. The native Celtic (the Britons were Celts) fertility goddess was known by many names, including Danu (from which the Irish band derives their name). Reams describes regional practices that acknowledge that spirit of the goddess is in the crop and that some of it should be left standing at harvest. Rather using the last stalks as food, they were woven into figures and displayed during harvest festivities.

Carole Somerville, also writing at helium.com, describes a medieval practice of either choosing a real woman as a “harvest queen” or making a “kirn-doll” and parading it through the streets on Thanksgiving Day. This brings up the revisionist sermon about how the meal shared by the “Pilgrims” and the Wampanoag in 1621 was not actually the “first Thanksgiving,” but rather Wampanoag choosing to diplomatically join their future foes in a traditional European harvest festival.

“Corn” in the background

It would be a charming fiction to introduce corn dollies to the story of the 1621 Thanksgiving and have the former East Anglians, who were supposedly out to purify the Christian faith, explain away the presence of these pagan idols. This is a cynical idea because it assumes that the Pilgrims were hypocrites, but their later actions with respect to the Wampanoag rather free us from any sympathy for them.

One could even make the tale fantasmagorical by telling it from the corn dolly’s point of view: a goddess temporarily imprisoned in a woven sheaf of corn stalks is the helpless witness to the betrayal of her fellow non-Christians. Let the weaving begin. And then the burning.

Plants That Don’t Cause Strife

Most people know “loosestrife” because of the veritable pestilence upon the landscape that is purple loosestrife and its relatively benign (albeit not harmless) distant relative yellow loosestrife, a deer-resistant (and therefore popular) denizen of perennial beds.

Lysimachos of Thrace

But what about that name? It has a potentially calamitous etymology if it has anything to do with the idea of “loosing strife upon the land.” But the real story is less exciting and a bit more pointy-headed.

The common name is given to members of two genera Lythrum and Lysimachia. Until the advent of molecular genetics both were thought to be members of the family Primulaceae (primroses), but recent evidence shows that Lysimachia should be put in the family Myrsinaceae and Lythrum in the family Lythraceae.

The common is name is a literal translation from the Greek lysimachia, which was the name for the flower in the Classical world. Lysis means ‘loose’ or ‘break apart,’ and mache means ‘to fight.’ What does this have to do with the properties of the plant? As it turns out: nothing.

In fact, according to Dioscorides and Pliny, the plant was named for King Lysimachos, who was apparently something of an herbalist and was the first to describe the curative properties of the herb. Lysimachos was one of the bodyguards of Alexander the Great, and after the young emperor’s death in 323 B.C.E. he became the ruler of Thrace, Asia Minor (Turkey) and Macedon.

Lysimachia vulgaris

The plant most consistently referred to as yellow loosestrife is Lysimachia vulgaris. The leaves are whorled on this species, and the flowers are arranged in loose spikes at the top of the stem. This species is regarded as being invasive in the United States, where it is found along wetter roadsides.

Lysimachia punctata is called either yellow or spotted loosestrife and is the most commonly seen member of the genus in perennial beds. Its shorter stemmed leaves are arranged in whorls like those of L. vulgaris, but unlike L. vulgaris, the flowers are arranged in whorls just above the leaf whorls. The overall effect is one of alternately circles of green and bright yellow climbing up the stem. This plant is not regarded as being nearly as invasive as L. vulgaris.

While most Lysimachia species are native to Europea and Asia, a few are native to North America, including the whorled loosestrife (Lysimachia quadrifolia), which is found in woodlands from Georgia to Hudson Bay east of the Mississippi River. Lysimachia fraseri (Fraser’s yellow loosestrife) is a rare denizen of the southeastern United States. Its numbers have been reduced by suppression of natural wildfires; it is usually sterile when it grows in excessive shade.

Lythrum salicaria

But the most notorious loosestrife is Lythrum salicaria or purple loosestrife, which spreads in clonal mats, crowding out native species, especially cattails in wetland settings. For several years volunteer groups were physically removing these plants from wildlife preserves and refuges because it was dominating the ecosystems to the extent that the food web was affected. Native insects adapted to eating and breeding on cattails and other species lost their habitat, sending a cascading wave of disruption through the community.

Integrated pest management (IPM) programs are the most ecologically sophisticated way to control invasive species. They will not eliminate the invader, but will (if successful) bring the numbers under control. In 1992 the U.S. Department of Agriculture approved the release of Galerucella spp. beetles to make an inroad into the infestation of purple loosestrife populations in North America. After the beetles are introduced, they begin to feed on the loosestrife, which becomes stunted and defoliated, allowing other plants to grow around it. However, it takes five to 10 years for sufficient numbers of beetles to build up and make a serious dent in the loosestrife populations.

For obvious reasons it is unwise to use either purple or yellow (L. vulgaris) in flower arrangements, however attractive both spiked inflorescences may be. On the other hand, the gooseneck loosestrife (Lysimachia clethroides) is frequently used in add interesting geometry to an arrangement. The white spike blooms from the base of the spike toward the tip, giving it a crooked appearance. This plant can also be somewhat invasive.

Arrangements Stay Put and Stay Wet

If your mother was interested in flower arranging, or you are a particularly attentive florist patron, or for some reason or another you have had to dismantle a flower arrangement, you may have encountered a green, spongy substrate into which all the cut flower stems had been thrust. Like Kleenex®, this product is often known by its brand name, Oasis®. Generally speaking, however, it is called “floral foam.” Floral foam performs the dual function of keeping a cut flower in the orientation that you desire and keeping the flower hydrated.

 

Floral foam can be cut into any shape.

Vernon L. Smithers of Akron, Ohio, who made it as a phenol-aldehyde, invented it in his lab in 1954. The often repeated story is that he had a flower arrangement in his lab that he was about the bring home to his wife, and he opined (in the way of chemists), “Wouldn’t it be nice to create substance that would keep this arrangement watered and upright?”

Apparently floral foam can also be made with a saturated solution of urea and formalin, combined with sulfuric acid to produce a mixture that quickly hardens into a ‘cross-linked thermostatic plastic,’ which is to say, a foam that is stable at room temperature. These substances – whether derived from urea or phenol-aldehydes – are referred to technically as “open- or close-celled foams”

The open-celled foam absorbs and retains water. It can be bought either already wetted or still dry, depending on the type of arrangement it is intended to hold. If bought dry and then wetted, it is advised that you set the dry brick of foam in a large container of water and let it absorb it at its own (fairly rapid) rate. Let it slowly sink into the water rather than forcing it under. The latter method will leave air bubbles in the areas of the foam; a flower stem in contact with a waterless area will immediately dry out and ruin an arrangement.

Spiked floral “frog”

Floral foam replaced an earlier method of maintaining an upright flower arrangement with all stems in a fixed position called the floral frog. The frog is a weighted object crowned by vertical spikes and/or a matrix of wire. They sit (squat) in a pool of water at the bottom of the flower vase, hence the name.

The older invention never went entirely out of style and because arguments based on sustainable use of resources are becoming more widely accepted, the frog may be poised to make a comeback. Some expert arrangements never gave up on the frogs because they felt that they worked better than foam blocks.

Wen Zientek-Sico argued that the foam actually impairs the ability of flowers to absorb water and nutrients, although she cites no reference for this. Her real reasons are admittedly personal: she likes to collect frogs because they come in so many interesting shapes and sizes. Zientek-Sico also points out that it is cheaper to use and re-use frogs than to continually buy foam, which, once full of holes from flower stems, does not work as well a second time.

Arrangement requiring either foam or frog.

The status quo, however, seems to be floral foam. In an online video at eHow.com, Amelia Tallman notes that floral foam makes it possible to put arrangements into all sorts of odd shaped containers. This is not a very good argument for using foam over frogs, because frogs permit the same (or nearly the same) versatility. Tallman seems to be speaking to an audience that has been simply sticking flowers in an upright vase over and over again.

Styrofoam® is also used for flower arrangements, although Connie Krochmal suggests that because it doesn’t hold water as well as the Oasis® phenolic foam, you are better off using it for autumn and winter arrangements of boxwoods and evergreens (“topiaries”), which can be kept green by just spraying them regularly.

It’s Complicated Being Green

Plants are green because their cells are filled with molecules of a pigment called chlorophyll. Chlorophyll is a protein bonded to magnesium and resembles hemoglobin structurally. Chlorophyll molecules are found in organelles called chloroplast, which look suspiciously like cyanobacteria.

Lynn Margulis

In 1966 Lynn Margulis, then on the faculty of the biology department at Boston University, published a paper called “The origin of mitosing eukaryotic cells,” which revived the idea that eukaryotic cells had evolved through endosymbiotic combinations of prokaryotic (bacteria) cells. Margulis’s own contribution, in addition to her review of earlier speculative work, was to actually document through observations the structural similarities between eukaryotic organelles and various bacteria.

Chloroplasts are plastids (organelles that make and store molecules) found in the cells of the Archaeoplastida, which includes plants, green and red algae and glaucophytes. These organisms are distinguished from animal cells by their lack of a centriole. Red algae are pigmented with cholorphyll a and phycobiliproteins, while green algae and plants are pigmented with chlorophyll a and b and lack phycobiliproteins. In chlorophyll b an oxygen ion is attached to the C7 carbon where an alkene group is attached in chlorophyll a.

Chlorophyll looks green because it doesn’t absorb light energy in the green portion of the spectrum well and that energy is there reflected from the surface of chlorophyll-bearing structures, making them appear green.

The energy absorbed in the blue and red portions of the light spectrum is drives a “redox” reaction, causing the “reaction center” of the molecule to donate an electron to another molecule, which in turns donates it to another, so on down a series of molecules called the “electron transport chain.”

The reaction center is “reset” to a neutral state by receiving an electron from the oxidation of water into H⁺ and O₂, which is the source of free oxygen in the atmosphere. When this reaction evolved in cyanobacteria in the Archaean Era at least 2.5 billion years ago. Over an unknown number of years photosynthesis by cyanobacteria introduced oxygen to the atmosphere, which had previously been composed of carbon dioxide and nitrogen compounds.

Chloroplast

The chlorophyll molecules are embedded in the membranes of thylakoids, disk-shaped suborganelles that are arranged in stacks called grana. The grana float in the stroma, a fluid inside of the chloroplast. The thylakoid membrane is the site of photosynthesis.

The electron flow described above is used to move H⁺ ions across the thylakoid membrane. The end of the electron transfer chain is NADH, which moves the H⁺ ion across the membrane from the chloroplast stroma into the thylakoid lumen in the process of becoming NAD⁺. This leads to a build-up of H⁺ ions on one side of the membrane. They re-cross at different site—where the enzyme ATP synthase is found—to induce the reaction between ADP and an inorganic phosphate to form ATP (adenosine triphosphate). ATP is an energy-rich molecule that serves as a coenzyme in the reactions that make many other molecules in the cell and in cell division (i.e. growth).

The actual making of ATP, NADH, and the production of free oxygen constitute what are called the “light dependent” or light reactions. The “light independent” or dark reactions reduce inorganic carbon dioxide (CO₂) to make organic compounds like glucose (C₆H₁₂0₆). The dark reactions actually continue at night, but do not stop during the day. However, the antecedents from the dark reactions are created through the light reactions, so without a light interval a plant will cease absorbing making organic compounds.

The “Keeling curve” of atmospheric CO2

The phenomenon can be seen in the cycling of atmospheric carbon dioxide in the well-known “Keeling curve” collected at Mauna Loa on the island of Hawaii. C. David Keeling of Scripps Oceanographic Institute started measuring atmospheric CO₂ at Mauna Loa in 1958. The Scripps data show an annual cycle that reflects the seasonality of atmospheric CO₂. As the vegetation greens up and grows in the northern hemisphere, it absorbs CO₂ and reduces its concentration in the atmosphere by a few parts per million. As winter sets in and the vegetation dies back, and the light reactions slow, the amount of CO₂ increases again. The amplitude of this seasonal cycle and the average value of CO₂ concentration in the atmosphere have been increasing continually since 1958.

Fit To Be Dried

One of the memories that I have from childhood and adolescence is climbing up into the second floor of our barn—it didn’t have a real loft—and seeing bunches of flowers hanging upside down along wires stretched between the roof beams. At some point in the 1970s my mother began growing flowers that were grown to be dried, as opposed to be cut and displayed fresh.

Statice (Limonium sinuatum)

I think that she had joined a garden club and had gotten into flower arranging. In the absence of a greenhouse to grow fresh flowers through the winter, one resorted to arranging dried flowers. One of the most popular species is statice (Limomium sinuatum) or “sea lavender,” which has small flowers surrounded by colorful bracts. When dried the crepe paper-like bracts persist and largely hold their color. Statice is relatively easy to grow, begins flower in the spring and keeps flowering until the frost kills it, and can be grown as an annual in Zones 2 through 7.

Other popular species that dry well include baby’s breath (Gypsophila), cockscomb (Celosia), amaranth (Amaranthus), salvia (Salvia), and goldenrod (Solidago). The simplest way to dry all of these is to hang them upside down in a dry, dark, well-ventilated place like my mother did. Humid places should be avoided, as the plants are likely to get moldy.

Dried goldenrod and hydrangea

If you have taken a botany course, then you are perhaps already aware of pressing flowers in order to preserve them for a herbarium collection. Nearly any flower can be dried in this manner, although many do not retain much color and all are, of course, flattened. Alternating layers of flowers and newsprint are stacked between two boards and weighted down with a heavy object. It takes about a month to dry them in this manner.

Any plant can also be dried by submerging it in two parts water and one part glycerine (antifreeze actually works). Fresh flowers are submerged for two or three weeks and then hung upside down to drive the glycerine to the extremities of the vegetation.

Silica gel will also dehydrate flowers. Packets of this substance are often found in packages that have been shipped long distance. It can be bought at most garden stores. Flowers must be buried in a closed container. Flowers dried by silica gel may rehydrate and wilt if they are not kept in a closed container after initial drying.

Any flower that is cut to be dried should be picked later in the day when the dew has evaporated from it. They should be bound together in bunch with a rubber band and placed in a cool, dark place immediately. It is best to pick flowers before they are fully open, as they will continue to mature after they are cut and before they are fully dried.

Flowers fade because the pigments in them oxidize in the presence of light and water. Drying them in the dark prevents oxidation and thus preserves the color. Subsequent fading of the color in the dried flower is caused by partial rehydration from moisture in the air, which allows the oxidation reaction to go forward.

Dried hydrangeas

Hydrangeas (also known as hortensia) are woody plants that produce beautiful dried blooms. Hydrangea flowers should be allowed to partially dry while still on the shrub. They are initially green, but as they dry, they turn blue (acidic soils) pink, or purple (alkaline soils).

Hydrangea flowers are either “mopheads” or “lacecaps”. The former are round panicles and the latter are flatter corymbs. Often the lacecap flower heads will have smaller, radially symmetrical blooms at the center and larger sterile asymmetrical bracts around the perimeter.

Hydrangeas do not need to be hung upside down to dry. They will dry even if they are put in a vase filled with water.å