Category: Horticulture Highlight

Horticulture Highlight: Lightning Survival

July 24, 2019

the tree

aspires to the sky

one branch, cracked by lighting.

scrapes the earth…

            -Grace Schulman

Red Oak struck by lightning in 2016

As beautiful as Mount Auburn is, our professional arborists and horticulturists constantly are coping with problems injuring and compromising plants’ health and/or lives. A cursory list of on-going concerns includes beech decline, viburnum leaf beetle, hemlock wooly adelgid, verticillium wilt, winter moth, fire blight, dogwood anthracnose, bronze birch borer, elm bark beetle, boxwood leaf miner, nectria canker, etc., etc.   A comprehensive list of concerns could fill this whole page. Many of these conditions have been dealt with in the past and our staffs’ extensive knowledge help with prevention strategies, constant monitoring, early diagnosis and appropriate best practices treatments of countless biotic and abiotic plant health issues.

However, one abrupt, unforeseen, injurious agent is lightning. Relatively few trees struck by lightning will be completely shattered or disintegrated by the strike. Some struck trees nonetheless are killed immediately. Some may die later within the same year. Others may linger alive for years before declining in health primarily due to increased stress, secondary pests and/or other problems. We have one of the latter, a red oak, Quercus rubra on Mist Path, struck on July 9, 2016.

Beginning in clouds with electrical sparks created by negatively charged and positively charged particles, there are different types of lightning; intra-cloud lightning, cloud-to-cloud lightning, and cloud-to-ground lightning. Cloud-to-ground lightning represents an exchange of massive electric current and damages and kills thousands of trees annually. The National Lightning Detection Network (NLDN) reported 21 million cloud-to-ground strikes in the lower 48 states in 1999, this averages more than one per second, every second of the year. Various other sources report even higher averages per second worldwide.

Back to our red oak, Quercus rubra on Mist Path, one of five red oaks believed to be as old as the cemetery, with a trunk circumference of almost 14-feet. The morning after this tree was struck the obvious observable damage was a 10-12-inch, scar of missing bark running from the ground up the length of the trunk in a slightly spiral pattern. Most lightning passes through trees because water is a better conductor of electricity than air. Water in trees is concentrated in the cambium tissue just under the bark. Electricity surging through this water results in it boiling explosively, blasting off the bark. That morning we found pieces of its bark as far as 115-feet away from the tree. Shortly thereafter our arborists pruned out the major limb where the strike occurred.

…But if we got struck by lightning –

not a lot; say glanced, or shaved,

there was a chance (we heard)

it wouldn’t be so bad:

a little refreshing,

a little like La Vita Nuova

in a readable translation…

            -Ange Mlinko

Paul Walker, Superintendent of Grounds, an arborist with almost forty years of experience here at Mount Auburn has been monitoring this tree since the lightning strike. He recalled that in his time here there have been 10 trees struck by lightning, including this one, and five of them have been oaks, 3 red oaks, one white oak and one black oak. Other trees struck were white pine, American ash, Douglas fir, black cherry and blue spruce. The spectrum of survivability from these 10 strikes ranges from one tree being killed instantly to another red oak lasting about 15 years before finally succumbing. Trees struck but surviving will suffer from a reduction in water movement capacity at the site of cambium loss, increased stress, lessened defensive capability in tolerating insects, fungi and disease. The lengthy wound on our red oak now measures 21-24-inches at its widest, and will continue to enlarge.

On a future visit to Mount Auburn, stop by and pay a tribute to this notable monarch displaying its will to survive.  

We had so little, yet we had so much:

Thunder and lightning at the lightest touch.

            -John M. Ridland

Common Privet, Ligustrum vulgare

June 4, 2019

To be of use

The people I love best

jump into work head first

without dallying in the shadows

They seem to become natives of that element

and swim off with sure strokes almost out of sight….

            -Marge Piercy

If we were to transpose Piercy’s above sentiment to plants used for hedging, many such lists might include evergreens of yew, boxwood, arborvitae, or holly. A greater number of deciduous choices for hedging could include lilac, forsythia, rose, viburnum, spiraea, azalea, and privet among many others.

We reach’d a meadow slanting to the North;

Down which a well-worn pathway courted us

To one green wicket in a privet hedge…

            -Alfred, Lord Tennyson

Common privet, Ligustrum vulgare are native to Europe and northern Africa. These are many branched, quick-growing shrubs capable of reaching 12 to 15-feet-high, with equally wide spread. The 1-to-2 ½-inch long, dark green, deciduous, simple leaves are placed opposite each other on the stems. In the sixteenth and seventeenth centuries, hedge mazes in large European gardens often were from clipped privet, yew or boxwood. Contemporary gardens still use privet for elaborate and simple hedges, as well as for creative topiary.

Introduced to our country by early settlers during colonial times, common privet eventually escaped from cultivation, becoming naturalized within certain areas of our native flora. This was documented by noted Swedish botanist/explorer Peter Kalm (1716-1779), an early student of and plant collector for Carl Linnaeus (1700-1778), the “father of modern taxonomy.” In his 1770 classic, Travels in North America, Kalm recorded for September 21, 1747, while in New Jersey, “The common privet, or Ligustrum vulgare, grows among the bushes in thickets and woods. But I cannot determine whether it belongs to the indigenous plants or to those which the English have introduced, the fruits of which the birds may have dispersed everywhere.”          

Several generations later visionary founder of Mount Auburn, Jacob Bigelow (1787-1879), physician and botanist, also documented this privet’s naturalized occurrence in his Florula Bostoniensis. A collection of Plants of Boston and its Vicinity, 1840 Third Edition Enlarged, “Leaves lanceolate, acute: panicle crowded. An ornamental shrub with smooth, opposite, spear-shaped leaves, thickening at the ends of the branches. Remarkable in summer for its panicles of small white flowers, and in autumn for its conical bunches of black berries. – frequent in woods and near fences, particularly in Roxbury.”

For those who might suggest that there are more privet hedges in this country than are needed, we end with notable garden writer Allen Lacy (1935-2015) from his 1984, Home Ground: A Gardener’s Miscellany, “…No garden visitor has ever bothered to praise my privet, but its gifts are not to be despised. I have given it no attention at all. I have neither fertilized it nor treated it to some of my precious compost nor watered it except incidentally…But it has thrived…In June it blooms for two weeks, with hundreds of creamy spikes made up of tiny flowers that sweeten the air…The bees love it, and some of its nectar may have found its way into the honey made by a neighbor who keeps bees…” We note here that everyone who has pruned or sheared their privet before the middle of June has already removed the flower buds. It is probable many hedge owners have never witnessed their flowers due to spring pruning and shaping.

Still

in a way

nobody sees a flower

really

it is so small

we haven’t the time

and to see takes time

like to have a friend takes

time

-Georgia O’Keefe

Lacy continues, “…Now its tangled branches have grown into a small thicket where robins nest each year in the spring and sparrows and finches perch in winter…The privet has become the token wild place in my garden, something that links it with the rhythms of the larger order of nature. This fall, like every fall, the abundant blue-black fruits of my privet will feed some of the birds that live year-round in the neighborhood and some of the other birds that gather briefly here before resuming their annual migration southward. Left to itself, with no intention or planning on my part, the common privet turns out to have uncommon quality.”

On a future visit to Mount Auburn look for some of our common and other privets on Fountain Avenue, Willow Avenue, Yarrow Path, Indian Ridge Path, Bluebell Path, Pilgrim Path, Spelman Road, Garden Avenue and Spruce Avenue among other locations.

Like a well-kept lawn a hedge means a well-considered garden.

-Ernest Henry Wilson

Trillium, wake-robin

April 30, 2019

Let us forget the sorrows: they are there

always, but Spring too seldom there;

Once in a life-time only; oh seize hold!

Sweet in the telling once, but not re-told.

In Nature’s cycle blessed once a year,

not long enough to savour, but more dear

for all the anguish of its brevity…

            -Vita Sackville-West

Any hypothetical definition of spring is subject to countless interpretations, frequently entwined with preferred blossoms. Locally, for some it may be magnolias on Commonwealth Avenue, cherries, serviceberries, dogwoods, redbuds, and/or crabapples at Mount Auburn. But for John Burroughs (1837-1921), American naturalist, he famously put it in print as the Trillium erectum, Wake-robin, red trillium, stinking Benjamin. His half-century literary conservationist career commenced in 1871 with Wake-Robin. His own page one therein, clearly defined spring for him, “…and when I have found the wake-robin in bloom I know the season is fairly inaugurated. With me this flower is associated, not merely with the awakening of Robin, for he has been awake for some weeks, but with the universal awakening and rehabilitation of nature.”

Usually not found by the drive-through spring adherents, these are aesthetic gifts to woodland path aficionados who may perchance be satisfied by a memorable encounter of even a single plant in blossom. Native to the eastern United States and Canada its purple/maroon flowers have three lance-shaped, prominently veined, petals. These perennial flowers are on a short stem (pedicel) above a whorl of three attractive, ovate, green leaves. These nectar-less flowers emit an odor which attracts flies and beetles as pollinators. The variant degrees of fetidness clearly are the source of the less complimentary colloquial name,stinking Benjamin. This allows use here of Alfred, Lord Tennyson’s (1809-1892) quatrain;

What is it? A learned man

Could give it a clumsy name,

Let him name it who can,

The beauty would be the same.

The genus Trillium comprises almost fifty species, primarily native to North America, but with ten species native to Asia. One distinct characteristic of this genus is myrmecochory, the dispersal of seeds by ants. The etymology is from the Greek for ant (myrmex) and dispersal (kore). When Trillium flowers have been successfully fertilized they will eventually produce a 1-inch to 1 1/2-inch, red, fruit capsule within which are numerous1/8-inch seeds. Attached to these seeds are elaiosomes, an appendage rich in nutrients, lipids and/or oleic acids. Ants take these seeds back to their nests to eat or feed their larvae the elaiosomes. The seeds then are discarded, outside or inside of the ant nest. This insect-plant interaction is not unique to trilliums, over 11,000 species of plants benefit from myrmecochory.

Other trillium species to look for include Trillium grandiflorum, big white trillium, which as the name suggests have three white petals. Also, the Trillium undulatum, painted trillium, which have white petals with a distinct red v-shaped marking near the base of each petal. On a future visit to Mount Auburn, look for trilliums at Dell Path, Sumac Path, Buttercup Path and at Spruce Knoll.

I have touched the trillium,

Pale flower of the land,

Coral, anemone,

And not your hand…

            -Helen Dudley