Sunday, December 26, 2010

Tree Leaves

What’s happening: The snow brought moisture, and the crust responded; moss in places last Sunday; looks like snow also loosened some rocks which came down into the arroyo; new basal growth on snapdragons Thursday.

What’s still green: Moss, juniper and other evergreens, Apache plume, yuccas, Japanese honeysuckle, pyracantha, grape hyacinth, large-leaved soapwort, sea pink, hollyhock, cheese, oriental poppy, blue flax, yellow and pink evening primroses, vinca, sweet pea, gypsum phacelia, tumble mustard, snakeweed, dandelion, anthemis, coreopsis, chrysanthemum, heath and strap leaf aster leaves; pampas and cheat grasses; rose stems and young chamisa branches.

What’s grey, blue-grey or grey-green: Piñon, four-winged salt bush, buddleia, pinks, snow-in-summer, loco weed, yellow alyssum, stick leaf, western stickseed, winterfat, golden hairy aster leaves.

What’s red/turning red: Cholla, prickly pear, small-leaved soapwort, beards tongues, coral bells leaves.

What’s yellow/turning yellow: Arborvitae; globe and weeping willow branches.

What’s blooming inside: Christmas cactus, aptenia, asparagus fern; chaste tree leaves dead.

Animal sightings: Robin in cottonwood Thursday; rabbit about.

Weather: Ground wet when I got up Wednesday morning, rain Thursday night turned to frost the next morning; 9:45 hours of daylight today.

Weekly update: A week ago Friday, one of the men I work with drove in from Pecos with a great, gaping hole in his windshield where a cottonwood branch had come down during the night. Snow and small branches still rode on the roof.

Cottonwoods have relatively soft, weak wood that doesn’t tolerate bending or compression. Ron Smith, of the North Dakota state extension service, calls them "free kindling," because they drop their branches so easily. There currently is a scatter of small, maybe half-inch thick, grey-white branches on the shoulder under a male cottonwood down the road.

One of the things that’s always puzzled me is why some local trees retain their leaves into winter and why those leaves don’t cause more problems for branches when they get wet or collect snow. I remember in Michigan the ice storms of January and February were always accompanied by broken limbs and downed power lines.

When the snow fell last week, my black locusts still had half their leaves, while the catalpa had some on its lowest branch and the cottonwood had scattered leaves near the bottom. Some cottonwoods growing near arroyos kept most of their leaves, while those near the river were bare.

This year the coming of winter in the Española valley has been marked by discrete, widely spaced events. We had our first hard freeze, when temperatures dropped into the high 20's, on October 26. Before that, the leaves on all three species were turning yellow in an orderly manner, but neither the locust nor the catalpa were prepared. The leaves on the one exotic turned dead green, the others brown. The native cottonwoods continued to yellow.

Night temperatures got decidedly colder, 20 on my front porch, on November 10. The cottonwood leaves turned brown.

The first snow moved through on November 16. When I woke the temperature was hovering around 32 and water was condensed on many leaves. I don’t know if we actually got snow, or only very cold moisture. The cottonwoods and catalpas dropped many of their leaves, but the locusts remained the same.

Another storm moved through on November 28, leaving snow in the mountains. High winds stripped my locusts of many of their leaves, especially toward the top. Three days later the morning temperature fell to 10 on my front porch. The remaining locust leaves turned brown.

Last week, the snow started falling just before dark on Thursday and stopped by the time blizzard conditions moved through the open lands between Santa Fé and Albuquerque that night. Pecos was already buried. The temperature was only 32 when I got home Friday night and little had changed except the roads were dry.

Saturday the sun never really broke through the clouds, but the temperature rose into the 40's. Snow either sank into the ground or evaporated into the air. Sunday morning was foggy from the heavy moisture load in the air. By mid afternoon, it was 50 on my front porch and most of the snow was gone.

Ice and leaves behaved the way I expected. On Saturday, evaporating water condensed on my metal roof and fell towards the roses’ drip line where it cooled as it dropped. When it landed on a vertical stem, it simply slid to the ground. When water landed on a leaf on a horizontal branch, it first encased the leaf in ice, then formed icicles which coalesced into elaborate, clear structures. Many rose leaves are now turning brown.

The immediate effect of cold damp wasn’t something I’d ever noticed before. Leaves on many non-woody plants turned black, especially the baptisia, which was never covered, and the purple coneflowers, which were buried. When I walked out towards the arroyo Sunday, I had a sense things were darker, but couldn’t identify any particular plant: it could have been the general wetness or it could have been leaves and stems darkening on some, but not all, individuals of plants like golden hairy asters.

The impact of the snow was less obvious. It tended to collect on lower, horizontal branches facing the storm. Leaves happened to be present on some of those branches that collected snow in my yard, but it was probably because both the leaves and the snow responded to similar wind patterns. The trunks of the trees must deflect the winds which keep leaves in place and allow snow to accumulate.

The weight of the snow did break the final connection between the leaves and the black locusts. By Saturday afternoon, there was a great mess of leaflets lying atop the snow. On the prairie, it looks like one cottonwood branch snapped, one that still retained its leaves. All the other downed wood looked old, long ago bleached and stripped of any signs of life.

The reason the leaves survived so long seems to be related to location as much as species. Botanists tell us plants respond to water stress and lower fall temperatures by slowing photosynthesis and producing abscisic acid, a hormone that seals the joints between leaves and stems so dead leaves can fall. If those biochemical messages are absent or contradictory, the plant is less likely to adapt to the changing season.

The cottonwoods growing on the relatively dry land back from the river near the city had no leaves this week, and the ground below was littered with long dead branches no one had cleared. Nothing looked like a new fall.

The cottonwood that lost its branch was growing in a gully cut by water leaving the end of an irrigation ditch for the arroyo. The tree that still has its leaves near the village sprouted in the run off of another irrigation ditch which has since dug a trench around the tree, exposing its roots. The arroyos kept running after the natural environment began to dry last fall, apparently countermanding any stress messages.

In my yard, the cottonwood is protected by a wooden fence on two sides, north and east. The surviving leaves are below the top of the fence towards the center of the tree. The locusts are close enough to the house, that the building may slow the wind near the ground where leaves still exist, while the leafy end of catalpa branch is less than 2' above the warmer ground.

The effect of piles of snow seems less important to trees than either damp or ice, which combines the weight of snow with the cold moisture. However, species seems more important than location. The locust shrugs off loosened leaves, while the cottonwood breaks from too much pressure.

Smith, Ron. "Questions on Cottonwood," North Dakota State University extension website.

Taylor, Jennifer L. "Populus deltoides," 2001, in United States Forest Service, on-line Fire Effects Information System.

Photograph: Cottonwood growing in a gully carved by an irrigation ditch, with a leaf laden broken branch, 24 December 2010.

Sunday, December 19, 2010

Russian Thistle

What’s happening: Ice forming on roses in the back drip line; most of the blackberry lily seeds have disappeared.

What’s still green: Juniper and other evergreens, some Apache plume, yuccas, some Japanese honeysuckle, pyracantha, red hot poker, grape hyacinth, Jupiter’s beard, large-leaved soapwort, sea pink, hollyhock, oriental poppy, blue flax, yellow and pink evening primroses, vinca, gypsum phacelia, tumble mustard, snakeweed, dandelion, anthemis, coreopsis, perky Sue, Shasta daisy, black-eyed Susan, strap leaf aster leaves; June, pampas, brome, cheat and base of needle grasses; rose stems and young chamisa branches.

What’s grey, blue-grey or grey-green: Piñon, four-winged salt bush, buddleia, pinks, snow-in-summer, loco weed, yellow alyssum, stick leaf, western stickseed, winterfat, golden hairy aster leaves.

What’s red/turning red: Privet, cholla, prickly pear, small-leaved soapwort, beards tongues, coral bells leaves.

What’s yellow/turning yellow: Arborvitae; globe and weeping willow branches.

What’s blooming inside: Aptenia, asparagus fern.

Animal sightings: The night after the snow fell a mouse was on my kitchen counter after I went to bed looking for food.

Weather: First snow Thursday; returned as fog this morning; 9:45 hours of daylight today.

Weekly update: Tuesday morning I could smell wood smoke when I walked out to my car. Across the river I could see dark smoke rising from someone burning. I’m not a good enough woodsmen to recognize the burning wood, but I can often tell when some one’s firing Russian thistle.

Most weeds produce a grey-white smoke. When Russian thistles ignite, which they do with a great whoosh, the smoke turns dark, with a touch of fatty yellow. The fumes are so acrid they attack my throat and make it difficult to breathe. My hair reeks until it’s washed.

When it grows in saline environments, Salsola tragus sequesters the salt it absorbs in vacuole sacs in its leaves. When it burns, the sodium is converted to carbonate of soda. If the soil is more normal, the alkaline ashes instead contain a carbonate of potash, itself a form of potassium.

Na2CO3, better known as washing soda, is used to bleach linen, for making soap and as the flux is manufacturing glass. The origins of glass making are lost in prehistory: Roman tradition gave credit to the Phoenicians, while the earliest evidence of a fully realized industry has been recovered from iron age Tell Amarna in Egypt dated around 1350 bc. The latter used soda from Lake Natron, while people living along the modern Syrian coast are the ones credited with discovering how to extract the compound from seaside plants.

The Romans mass produced glass, especially in Sidon in modern Lebanon where someone introduced glass blowing during the time of Augustus (31 bc–14 ad). The Romans later took glass making to Valencia and Murcia in Spain, areas conquered by the Umayyads of Syria in 714.

By the time Renaissance industrial demand increased, farmers around Cartagena in Murcia and Alacant on the Valencian coast planted barrilla, which was burned in pits covered with earth where the sodium carbonate had to be broken from the walls with hammers.

The most likely plants used by the Spanish were Salsola soda, Salsola kali, and Salsola sativa, now classed as Halogeton sativus.

The idea of burning the annual chenopods spread north to France where Salsola kali and our Russian thistle, there called soude épineuse or thorny soda, were used to produce blanquette around Montpellier, between Frontignan and Aiguemortes. The plants weren’t seeded like they were in Spain, but were burned in heaps in trenches for 8 or 9 days in late summer. The soda formed an "adhesive, almost vitreous mass" that remained red hot. When the blanquette cooled, it hardened and turned black. Water was then used to extract it from the residue.

The best always came from the Levant and was used to produce the clear cristallo glass made for Venice at Murano. The soda from Spain produced a bluish glass, while that from France was greenish.

The demand for organic sources for glass making declined after Nicolas Leblanc patented a process to produce sodium carbonate from salt, sulfuric acid, limestone and coal in 1791. In 1861, Ernest Solvay substituted ammonia for the acid. Mass production and a taste for large windows followed.

However, the need to burn weeds persisted. People here don’t burn Russian thistles because of some ties to a coastal Spain they never knew, nor have then reinvented something in the face of recurring circumstances. Instead, burning’s a relic from the time before the Phoenicians when the transformative power of fire was culturally important for both pragmatic and philosophical reasons.

Glass is a pyramid of fires. Natural glass is formed when fire heats the underlying sand to produce obsidian. The soda that lowers the melting temperature comes from burning weeds. The lime that stabilizes the soda-silica compound often comes from burning shells or limestone. Man-made glass forms when quartz granules are burned with soda and lime.

Science has demystified fire by calling it heat. Urban life and, more recently, anti-burning ordinances have done much to eliminate fire from our inherited tool kit, but it persists here in the Española valley in the varieties of smoke that greet one in the morning.

Burning is still a primordial ritual that inspires fear when thistles ignite, even if the curiosity to rake through the ashes has been lost.

Notes: Glass color doesn’t come from the soda, but from mineral impurities or additives in the mix.

Chaptal, Jean-Antoine-Claude. "Blanquette" in Chemistry Applied to Arts and Manufactures, volume 2, 1807.

Guibourt, Nicolas Jean Baptiste Gaston. Work near Cherbourg published in Journal de Chimie Medicale in March 1840 and reported as "Analysis of the Ashes of the Salsola tragus" in The London and Edinburgh Philosophical Magazine and Journal of Science, July 1840.

Kauffman, C. H. "Barilla" in The Dictionary of Merchandise, and Nomenclature in All Languages, 1805.

Nesbitt, Alexander and Henry James Powell. "History of Glass Manufacture" in Encyclopedia Britannica, 1911.

Pliny the Elder (Gaius Plinius Secundus). Naturalis Historia, translated by John F. Healy as Natural History: A Selection, 1991.

Photograph: Russian thistle just after it ignited in the gathering mist before the snow, 16 December 2010; winterfat in back is not burning; all the flame and smoke are from a single plant.

Sunday, December 12, 2010

Russian Olive

What’s happening: Cold dry mornings have been killing off many leaves that remained; rose leaves, some junipers and the edges of some prickly pears bronzing; gumweed seeds disappearing.

What’s still green: Juniper and other evergreens, Apache plume, yuccas, Japanese honeysuckle, pyracantha, red hot poker, grape hyacinth, Jupiter’s beard, large-leaved soapwort, sea pink, snapdragon, hollyhock, oriental poppy, blue flax, yellow and pink evening primroses, vinca, gypsum phacelia, tumble mustard, snakeweed, dandelion, anthemis, some coreopsis, perky Sue, Shasta daisy, some black-eyed Susan, strap leaf aster leaves; June, pampas, brome, cheat and base of needle grasses; young chamisa branches.

What’s grey, blue-grey or grey-green: Piñon, four-winged salt bush, buddleia, pinks, snow-in-summer, loco weed, yellow alyssum, stick leaf, western stickseed, winterfat, Silver King artemisia, golden hairy aster leaves.

What’s red/turning red: Privet, rose, cholla, prickly pear, small-leafed soapwort, beards tongues, coral bells leaves.

What’s yellow/turning yellow: Arborvitae; globe and weeping willow branches.

What’s blooming inside: Aptenia, asparagus fern.

Animal sightings: Now that leaves have fallen, I can see several birds' nests in my neighbor’s apricot, the one near the road with a number of vertical branches that grew after it was pruned.

Weather: Cold morning temperatures are earlier than usual; last rain 10/21/10; 9:47 hours of daylight today.

Weekly update: If I took the number of volunteer plants in my yard as an indicator, then the birds in this area prefer the berries of Virginia creeper and Russian olive over all others.

Hawks Aloft found, when it monitored birds in the bosque between Rio Rancho and Los Lunas for the Corps of Engineers between 2003 and 2008, that the Russian olive, so disparaged by environmentalists for filling the void left by the disappearing cottonwoods, is actually filling a much larger hole for migrating birds whose habitats are vanishing with suburban development. The highest densities and greatest diversity of species in winter were found in pure stands of Elaeagnus angustifolia.

The native of the collision belt between the Eurasian continent and the more southerly plates begins leafing the middle of April. The four-lobed tubular flowers appear a month later on branches they have lengthened from buds formed the previous year. However, you only know because you can smell them. The small pale yellow clusters are hidden by umbrellas of narrow, grey leaves on reddish twigs covered with grey scales.

Last year I saw incised fruits on my tree the first of July. They were gone before the end of summer. The tree in the wide arroyo produced small, round grey-green olives the middle of July that were disappearing by the end of September.

Unlike many deciduous trees whose leaves turn color, then drop, Russian olive leaves seem to just dry in late September and fold into narrow pendants that won’t hold ice or snow if the weather turns bad prematurely and make the ripening berries more visible. If they’re not eaten, the polished tan berries can last until late winter, when they begin to shrivel.

Hawks Aloft found many birds ignored them in the fall, if there was a large sunflower crop. However, neo-tropical animals like Wilson’s Warbler and the Western Tanager ate the berries, as did migrating robins, hermit thrushes, and white crowned and song sparrows.

The fruit continues to age during the cold, when it’s more important for birds wintering in the bosque. For instance, Stellar’s Jay was there in 2008 when the cone crop was less plentiful at higher elevations. Eastern blue birds have become permanent residents. Others that eat the fruit in the shortened days include western and mountain blue birds, both types of sparrows, American robins, red-winged blackbirds, northern flickers, hermit thrushes, yellow-rumped warblers, spotted towhees, and dark-eyed juncos.

Russian olives continue to be important in spring, when little new has appeared in the landscape. Of the 18 vegetation communities observed by Hawks Aloft from 63 locations, the nitrogen fixing members of the oleaster family attracted the second highest density of terrestrial birds, and were particularly important to cedar waxwings. In other parts of the country, those birds eat pyracantha berries in fall.

Where I live is close enough to the river to hear migrating geese in the morning and see occasional flocks overhead, but too far away to attract visitors. Occasionally a robin will appear in late May, usually near the orchards and open fields near the village.

The orchards provide both the remains of previous crops and large swaths of non-native grasses, like smooth brome, with all the seeds, insects and worms they bring. They also have no dogs, infrequent human visitors, and cars that are a goodly distance away.

This spring was unusual. Robins seemed to have started out earlier than usual, then were forced to lay over in this less than optimal area. I saw one along the side of the main road in February, when I was also hearing water fowl. The end of the month, I saw larger numbers around the orchards.

The middle of March, some had moved two miles south to my uphill neighbor’s yard, especially the area where the previous owner had kept horses. The end of the month, two small birds were in my catalpa. The next day one was in the peach next to my house. In mid April, there was one in the cottonwood between the catalpa and the old paddock. I last saw a robin in a front yard orchard on the main road the end of May.

Meantime, I saw some unusual slate-blue colored birds with brighter, darker heads on May 2 in the still barren Russian olives that line a lot next to the other, narrower arroyo that has the remains of some kind of lawn. I don’t know if those trees still had berries - it’s much harder to see such things in someone else’s yard - but this fall they have large fruits, while my tree and the one in the wide arroyo produced nothing this summer.

The skin color has faded to bleached wood. Most still have pockmarked surfaces, but the sides of some are becoming smooth and glisten in the sun. When one’s plucked, the short stem snaps, but the fruit resists pressure. However, when it’s broken, the outer skin is as pliable as an orange peel. The layer between the rind and the large seed has begun to dessicate: the mesocarp crumbles in the fruits that have begun to turn golden, is a bit more adhesive in the less mature ones.

At this time, the fructose and glucose are concentrated in the rind, but the drying pulp still has some flavor. When Steve Brill bit into a ripe fruit, he said "it tasted great - like a sweet raisin - for the first five seconds. Then it seemed like I had a mouthful of talcum powder."

Local birds, like the smallish brown ones that moved into my eastern neighbor’s metal building, have no problems eating the mealy drupes. A tree is now growing at the corner of his barn, and I suspect that that tree is the source of all the seedlings I removed from areas near the utility line this spring.

Whether or not natural selection is purely random or has purposefully favored the trees that support symbiotic birds is a philosophical, perhaps even a theological question. What’s obvious is that the large, striped seeds obviously aren’t damaged by their middle passage.

Notes: Thanks to an anonymous friend who was willing to taste the separate parts of a berry.

Brill, Steve. Identifying and Harvesting Edible and Medicinal Plants, 1994, with illustrations by Evelyn Dean.

Hawks Aloft, Albuquerque. Bird and Vegetation Community Relationships in the Middle Rio Grande Bosque: 2008 Interim Report, May 2009.

Photograph: Russian olive berries on a tree near the narrow arroyo, 5 December, 2010; the joint between this year’s growth and last is clear with the change in branch color; buds for next year’s growth and the dried tear drop leaves are also visible.

Sunday, December 05, 2010


What’s happening: Sunday’s winds removed most of the black locust leaves; next year’s buds forming on apricots; people are putting out their Christmas lights.

What’s still green: Juniper and other evergreens, Lady Banks, hybrid tea and floribunda roses, Apache plume, prickly pear, yuccas, Japanese honeysuckle, pyracantha, red hot poker, grape hyacinth, west-facing iris, bouncing Bess, Jupiter’s beard, large-leaved soapwort, sea pink, snapdragon, catmint center, white sweet clover, sweet pea, hollyhock, oriental poppy, blue flax, Saint John’s wort, yellow evening primrose, vinca, alfilerillo, gypsum phacelia, tumble mustard, snakeweed, dandelion, anthemis, coreopsis, perky Sue, Shasta daisy, black-eyed Susan, strap leaf aster leaves; June, pampas, brome, cheat and base of needle grasses; young chamisa branches.

What’s grey, blue-grey or grey-green: Piñon, four-winged salt bush, buddleia, pinks, snow-in-summer, loco weed, yellow alyssum, stick leaf, western stickseed, winterfat, Silver King artemisia, golden hairy aster leaves.

What’s red/turning red: Pivet, barberry, cholla, small-leaved soapwort, beards tongues, hartweig and pink evening primroses, coral bell leaves.

What’s yellow/turning yellow: Arborvitae, golden spur columbine leaves; globe and weeping willow branches.

What’s blooming inside: Aptenia, asparagus fern.

Animal sightings: When I was cleaning the irrigation timers I discovered insect webs clogging the screen filters; since no area seemed to suffer from a serious lack of water, I assume this happened late in the season.

Weather: A storm passed through last weekend, leaving snow in the Jemez that lasted as a day and cold morning temperatures for part of the week; last rain 10/21/10; 9:54 hours of daylight today.

Weekly update: Pyracanthas always look like unhappy migrants from a more southern clime, huddled against walls as they are, pulling their faded cloaks of orange about them. At this time of year, when native plants are shades of brown, they’re the only color in the landscape.

I’m not sure why I associate the exotic shrubs with the south, beyond the fact they’re natives of the Caucasus, Iranian and Turkish plates, and Baltic, Italian and Iberian peninsulas that aren’t reliably hardy beyond zone 6 without protection, especially from the wind. The evergreen leaves turn bronze, then drop in this area.

But, for some reason, they’re part of this northerner’s view of the domestic landscape from Charleston to Dallas, even though green thorn first entered England in the early 1600's as a hedge plant. The idea of a thorny barrier to protect property is so obvious it’s been invented many times, most recently with razor wire.

In the first century before Christ, Varro recommended Roman land owners plant hedges of thorn because they couldn’t be destroyed by malicious torchers. A century later Columella believed hedges lasted longer than other barriers and recommended planting seeds from plants with the largest thorns.

A few centuries later, Romans introduced thorned hedges into an area where iron age settlers had used ditches to protect their village on the Thames near Oxford. When the Romans left their botanical debris in England, the natives reverted to their usual practices and hedges were forgotten until the early years of the Stuarts, who ascended the throne with James I in 1603, when land owners began claiming common lands as their own. The idea of thorny hedges was introduced as the best means to enforce their claims against displaced tenants. They were soon paired with berms and ditches.

It was in those years, between the time John Gerard published his Herbal in 1597 and John Parkinson described his garden in 1629, that pyracantha was introduced. The first didn’t mention the shrub; the latter praised the fire thorn hedge that led to his orchard.

John Loudon believes those early hedges were mixed lots, grown from whatever was available, until stock nurseries developed. The primary requirements for shrubs were that they grew quickly, lived long, could be made dense, had lots of thorns and were cheap to produce.

The most common plants became hawthorn or white thorn (Crataegus oxyacantha), black thorn (Prunus spinosa) and buck thorn (Rhamnus catharticus). When hedges were introduced into this country, Osage orange and Cherokee rose were used in the south. If one were going to grow a thorn hedge here, one would prune Russian olive and black locust.

Although the Southern Cultivator was recommending pyracantha’s use in 1855, the shrub didn’t appear prominently in the south until George Washington Vanderbilt built his mansion on cutover land near Asheville, North Carolina, between 1889 and 1895. He told Frederick Lee Olmsted he wanted an European estate.

The landscaper interpreted that loosely, but did suggest a traditional walled garden like those associated with monasteries. Vanderbilt ruled out the utilitarian plants grown in such plots, so Olmsted espaliered Roses of Sharon and members of the rose family along the walls, including apples, pears, apricots and pyracanthas.

Biltmore became not simply a northerner’s southern retreat, but the image for many northerners of what southern plantations should be. The nursery that supplied the estate was soon telling other wholesale customers the evergreen thorn belonged "in every collection."

Olmsted’s use of Pyracantha coccinea was aided by the Lalande nursery in Nantes who had released a cultivar in 1874 that produced more berries on longer, more flexible branches that were also hardier in cold weather. They could be used in front of town houses to protect the windows from intruders while providing some aesthetic veneer.

It’s Lalande’s vertical shrubs that are growing near the village today. When people bought them years ago they probably had no particular image of the plants, and did what one does with thorns - put them near the road, far from the house, and left them alone.

The one that’s most visible, growing where a front block wall meets a side chain link fence, has one main stem that’s branched with a couple smaller glossy brown stems rising from the crown. The lower parts are bare, with the leaves concentrated on newer growth that’s splays across the fence where the five-petaled white flowers and orange berries are borne.

If one wanted them to form a barrier, one would need to constantly prune to encourage new growth at the base. Someone is maintaining such a group in the stone well in front of an empty bank by the old post office where the shrubs form deep green columns that reach nearly to the top of the building. However, the mealy fruit is concentrated at the top, because it grows on old wood that tends to be trimmed away and only survives where new growth is safe.

The thorns aren’t obvious when one drives by the drooping branches, but are felt as soon as one touches the ovate leaves. Rather than the prickles found along the stems of roses, pyracantha’s spines are sharpened, inch or longer spurs that grow from the same node as the leaves.

Without some variation in their mass, the single plants simply look dreary - the neglected ones scraggly and berry laden, the tended ones neat and colorless. In such isolated communities they look like the displaced visitors they, in fact, are.

Notes:Alexander, Bill. The Biltmore Nursery: A Botanical Legacy, 2007, reprints their catalog.

Columella, Lucius Junius Moderatus. De Re Rustica, anonymously translated in 1745 as L. Junius Moderatus Columella of Husbandry.

Gerard, John. Gerard’s Herball, 1597; Alice M. Coats notes the missing reference in Garden Shrubs and Their Histories, 1964, republished in 1992 with notes by John L. Creech.

Lambrick, George and Mark Robinson. Iron Age and Roman Riverside Settlements at Farmoor, Oxfordshire, 1979.

Loudon, John Claudius. Arboretum et Fruticetum Britannicum, volume 2, 1838.

Parkinson, John. Paradisi in Sole Paradisus Terrestris, 1629; described in Anna Parkinson, Nature's Alchemist: John Parkinson, Herbalist to Charles I, 2007.

Southern Cultivator, The. "Crataegus pyracantha, or Evergreen Thorn, for Hedging," 1855, quoted in James R. Cothran, Gardens and Historic Plants of the Antebellum South, 2003; pyracantha has had several botanical designations, including as a hawthorn.

Varro, Marcus Terentius. Rerum Rusticarum Libri III, translated by Fairfax Harrison in Roman Farm Management: The Treatises of Cato and Varro, 1913.

Photograph: Pyracantha berries growing near the village, 28 November 2010; the spine in the center is probably a spur for future growth; thorns are above the leaves, narrow and pointed, not below, but grow at a similar angle.